scsi: storvsc: Properly support FC hosts

PATCH Superseded K. Y. Srinivasan 3 participants 18 messages Dec 13, 2015 – Dec 21, 2015

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K. Y. Srinivasan

author

2015-12-13 18:54 UTC #0 lore raw

v3 cover scsi: storvsc: Properly support FC hosts

Properly support FC hosts. Additional cleanup patches are also included.

V2: Comments from Dan Carpenter <[email protected]> and
from Johannes Thumshirn <[email protected]> addressed.

V3: Fixed build issues reported by kbuild test robot <[email protected]>

K. Y. Srinivasan (4):
scsi: storvsc: Fix a bug in the layout of the hv_fc_wwn_packet
scsi: storvsc: Properly support Fibre Channel devices
scsi: storvsc: Refactor the code in storvsc_channel_init()
scsi: storvsc: Tighten up the interrupt path

 drivers/scsi/storvsc_drv.c |  275 +++++++++++++++++++++++++------------------
 1 files changed, 160 insertions(+), 115 deletions(-)

Signature · 1 line

1.7.4.1

K. Y. Srinivasan

author

2015-12-13 18:55 UTC #1 lore raw

PATCH v3 1/4 scsi: storvsc: Fix a bug in the layout of the hv_fc_wwn_packet

The hv_fc_wwn_packet is exchanged over vmbus. Make the definition in Linux match the Window's definition.

Signed-off-by K. Y. Srinivasan <[email protected]>

Reviewed-by Johannes Thumshirn <[email protected]>

Reviewed-by Long Li <[email protected]>

Tested-by Alex Ng <[email protected]>

---
 drivers/scsi/storvsc_drv.c |    5 ++---
 1 files changed, 2 insertions(+), 3 deletions(-)

drivers/scsi/storvsc_drv.c +2 -3

index c41f674..00bb4bd 100644
@@ -92,9 +92,8 @@ enum vstor_packet_operation {
  */
 
 struct hv_fc_wwn_packet {
-	bool	primary_active;
-	u8	reserved1;
-	u8	reserved2;
+	u8	primary_active;
+	u8	reserved1[3];
 	u8	primary_port_wwn[8];
 	u8	primary_node_wwn[8];
 	u8	secondary_port_wwn[8];

Signature · 1 line

1.7.4.1

K. Y. Srinivasan

author

2015-12-13 18:55 UTC #2 lore raw

PATCH v3 2/4 scsi: storvsc: Properly support Fibre Channel devices

For FC devices managed by this driver, atttach the appropriate transport template. This will allow us to create the appropriate sysfs files for these devices. With this we can publish the wwn for both the port and the node.

Signed-off-by K. Y. Srinivasan <[email protected]>

Reviewed-by Long Li <[email protected]>

Tested-by Alex Ng <[email protected]>

---
V2: Fixed error paths - Dan Carpenter <[email protected]>
V3: Fixed build issues reported by kbuild test robot <[email protected]>

 drivers/scsi/storvsc_drv.c |  181 ++++++++++++++++++++++++++++++++-----------
 1 files changed, 134 insertions(+), 47 deletions(-)

drivers/scsi/storvsc_drv.c +134 ~~-47~~

index 00bb4bd..220b794 100644
@@ -41,6 +41,7 @@
 #include <scsi/scsi_eh.h>
 #include <scsi/scsi_devinfo.h>
 #include <scsi/scsi_dbg.h>
+#include <scsi/scsi_transport_fc.h>
 
 /*
  * All wire protocol details (storage protocol between the guest and the host)

@@ -397,6 +398,9 @@ static int storvsc_timeout = 180;
 
 static int msft_blist_flags = BLIST_TRY_VPD_PAGES;
 
+#ifdef CONFIG_SCSI_FC_ATTRS
+static struct scsi_transport_template *fc_transport_template;
+#endif
 
 static void storvsc_on_channel_callback(void *context);

@@ -456,6 +460,11 @@ struct storvsc_device {
 	/* Used for vsc/vsp channel reset process */
 	struct storvsc_cmd_request init_request;
 	struct storvsc_cmd_request reset_request;
+	/*
+	 * Currently active port and node names for FC devices.
+	 */
+	u64 node_name;
+	u64 port_name;
 };
 
 struct hv_host_device {

@@ -695,7 +704,26 @@ static void  handle_multichannel_storage(struct hv_device *device, int max_chns)
 	vmbus_are_subchannels_present(device->channel);
 }
 
-static int storvsc_channel_init(struct hv_device *device)
+static void cache_wwn(struct storvsc_device *stor_device,
+		      struct vstor_packet *vstor_packet)
+{
+	/*
+	 * Cache the currently active port and node ww names.
+	 */
+	if (vstor_packet->wwn_packet.primary_active) {
+		stor_device->node_name =
+			wwn_to_u64(vstor_packet->wwn_packet.primary_node_wwn);
+		stor_device->port_name =
+			wwn_to_u64(vstor_packet->wwn_packet.primary_port_wwn);
+	} else {
+		stor_device->node_name =
+			wwn_to_u64(vstor_packet->wwn_packet.secondary_node_wwn);
+		stor_device->port_name =
+			wwn_to_u64(vstor_packet->wwn_packet.secondary_port_wwn);
+	}
+}
+
+static int storvsc_channel_init(struct hv_device *device, bool is_fc)
 {
 	struct storvsc_device *stor_device;
 	struct storvsc_cmd_request *request;

@@ -727,19 +755,15 @@ static int storvsc_channel_init(struct hv_device *device)
 			       VM_PKT_DATA_INBAND,
 			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
 	if (ret != 0)
-		goto cleanup;
+		return ret;
 
 	t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
-	if (t == 0) {
-		ret = -ETIMEDOUT;
-		goto cleanup;
-	}
+	if (t == 0)
+		return -ETIMEDOUT;
 
 	if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO ||
-	    vstor_packet->status != 0) {
-		ret = -EINVAL;
-		goto cleanup;
-	}
+	    vstor_packet->status != 0)
+		return -EINVAL;
 
 
 	for (i = 0; i < ARRAY_SIZE(vmstor_protocols); i++) {

@@ -764,18 +788,14 @@ static int storvsc_channel_init(struct hv_device *device)
 			       VM_PKT_DATA_INBAND,
 			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
 		if (ret != 0)
-			goto cleanup;
+			return ret;
 
 		t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
-		if (t == 0) {
-			ret = -ETIMEDOUT;
-			goto cleanup;
-		}
+		if (t == 0)
+			return -ETIMEDOUT;
 
-		if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO) {
-			ret = -EINVAL;
-			goto cleanup;
-		}
+		if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO)
+			return -EINVAL;
 
 		if (vstor_packet->status == 0) {
 			vmstor_proto_version =

@@ -791,10 +811,8 @@ static int storvsc_channel_init(struct hv_device *device)
 		}
 	}
 
-	if (vstor_packet->status != 0) {
-		ret = -EINVAL;
-		goto cleanup;
-	}
+	if (vstor_packet->status != 0)
+		return -EINVAL;
 
 
 	memset(vstor_packet, 0, sizeof(struct vstor_packet));

@@ -809,19 +827,15 @@ static int storvsc_channel_init(struct hv_device *device)
 			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
 
 	if (ret != 0)
-		goto cleanup;
+		return ret;
 
 	t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
-	if (t == 0) {
-		ret = -ETIMEDOUT;
-		goto cleanup;
-	}
+	if (t == 0)
+		return -ETIMEDOUT;
 
 	if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO ||
-	    vstor_packet->status != 0) {
-		ret = -EINVAL;
-		goto cleanup;
-	}
+	    vstor_packet->status != 0)
+		return -EINVAL;
 
 	/*
 	 * Check to see if multi-channel support is there.

@@ -837,6 +851,38 @@ static int storvsc_channel_init(struct hv_device *device)
 	stor_device->max_transfer_bytes =
 		vstor_packet->storage_channel_properties.max_transfer_bytes;
 
+	if (!is_fc)
+		goto done;
+
+	memset(vstor_packet, 0, sizeof(struct vstor_packet));
+	vstor_packet->operation = VSTOR_OPERATION_FCHBA_DATA;
+	vstor_packet->flags = REQUEST_COMPLETION_FLAG;
+
+	ret = vmbus_sendpacket(device->channel, vstor_packet,
+			       (sizeof(struct vstor_packet) -
+			       vmscsi_size_delta),
+			       (unsigned long)request,
+			       VM_PKT_DATA_INBAND,
+			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
+
+	if (ret != 0)
+		return ret;
+
+	t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
+	if (t == 0)
+		return -ETIMEDOUT;
+
+	if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO ||
+	    vstor_packet->status != 0)
+		return -EINVAL;
+
+	/*
+	 * Cache the currently active port and node ww names.
+	 */
+	cache_wwn(stor_device, vstor_packet);
+
+done:
+
 	memset(vstor_packet, 0, sizeof(struct vstor_packet));
 	vstor_packet->operation = VSTOR_OPERATION_END_INITIALIZATION;
 	vstor_packet->flags = REQUEST_COMPLETION_FLAG;

@@ -849,25 +895,19 @@ static int storvsc_channel_init(struct hv_device *device)
 			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
 
 	if (ret != 0)
-		goto cleanup;
+		return ret;
 
 	t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
-	if (t == 0) {
-		ret = -ETIMEDOUT;
-		goto cleanup;
-	}
+	if (t == 0)
+		return -ETIMEDOUT;
 
 	if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO ||
-	    vstor_packet->status != 0) {
-		ret = -EINVAL;
-		goto cleanup;
-	}
+	    vstor_packet->status != 0)
+		return -EINVAL;
 
 	if (process_sub_channels)
 		handle_multichannel_storage(device, max_chns);
 
-
-cleanup:
 	return ret;
 }

@@ -1076,6 +1116,14 @@ static void storvsc_on_receive(struct hv_device *device,
 		schedule_work(&work->work);
 		break;
 
+	case VSTOR_OPERATION_FCHBA_DATA:
+		stor_device = get_in_stor_device(device);
+		cache_wwn(stor_device, vstor_packet);
+#ifdef CONFIG_SCSI_FC_ATTRS
+		fc_host_node_name(stor_device->host) = stor_device->node_name;
+		fc_host_port_name(stor_device->host) = stor_device->port_name;
+#endif
+		break;
 	default:
 		break;
 	}

@@ -1131,7 +1179,8 @@ static void storvsc_on_channel_callback(void *context)
 	return;
 }
 
-static int storvsc_connect_to_vsp(struct hv_device *device, u32 ring_size)
+static int storvsc_connect_to_vsp(struct hv_device *device, u32 ring_size,
+				  bool is_fc)
 {
 	struct vmstorage_channel_properties props;
 	int ret;

@@ -1148,7 +1197,7 @@ static int storvsc_connect_to_vsp(struct hv_device *device, u32 ring_size)
 	if (ret != 0)
 		return ret;
 
-	ret = storvsc_channel_init(device);
+	ret = storvsc_channel_init(device, is_fc);
 
 	return ret;
 }

@@ -1573,6 +1622,7 @@ static int storvsc_probe(struct hv_device *device,
 	struct Scsi_Host *host;
 	struct hv_host_device *host_dev;
 	bool dev_is_ide = ((dev_id->driver_data == IDE_GUID) ? true : false);
+	bool is_fc = ((dev_id->driver_data == SFC_GUID) ? true : false);
 	int target = 0;
 	struct storvsc_device *stor_device;
 	int max_luns_per_target;

@@ -1630,7 +1680,7 @@ static int storvsc_probe(struct hv_device *device,
 	hv_set_drvdata(device, stor_device);
 
 	stor_device->port_number = host->host_no;
-	ret = storvsc_connect_to_vsp(device, storvsc_ringbuffer_size);
+	ret = storvsc_connect_to_vsp(device, storvsc_ringbuffer_size, is_fc);
 	if (ret)
 		goto err_out1;

@@ -1642,6 +1692,9 @@ static int storvsc_probe(struct hv_device *device,
 		host->max_lun = STORVSC_FC_MAX_LUNS_PER_TARGET;
 		host->max_id = STORVSC_FC_MAX_TARGETS;
 		host->max_channel = STORVSC_FC_MAX_CHANNELS - 1;
+#ifdef CONFIG_SCSI_FC_ATTRS
+		host->transportt = fc_transport_template;
+#endif
 		break;
 
 	case SCSI_GUID:

@@ -1681,6 +1734,12 @@ static int storvsc_probe(struct hv_device *device,
 			goto err_out2;
 		}
 	}
+#ifdef CONFIG_SCSI_FC_ATTRS
+	if (host->transportt == fc_transport_template) {
+		fc_host_node_name(host) = stor_device->node_name;
+		fc_host_port_name(host) = stor_device->port_name;
+	}
+#endif
 	return 0;
 
 err_out2:

@@ -1706,6 +1765,10 @@ static int storvsc_remove(struct hv_device *dev)
 	struct storvsc_device *stor_device = hv_get_drvdata(dev);
 	struct Scsi_Host *host = stor_device->host;
 
+#ifdef CONFIG_SCSI_FC_ATTRS
+	if (host->transportt == fc_transport_template)
+		fc_remove_host(host);
+#endif
 	scsi_remove_host(host);
 	storvsc_dev_remove(dev);
 	scsi_host_put(host);

@@ -1720,8 +1783,16 @@ static struct hv_driver storvsc_drv = {
 	.remove = storvsc_remove,
 };
 
+#ifdef CONFIG_SCSI_FC_ATTRS
+static struct fc_function_template fc_transport_functions = {
+	.show_host_node_name = 1,
+	.show_host_port_name = 1,
+};
+#endif
+
 static int __init storvsc_drv_init(void)
 {
+	int ret;
 
 	/*
 	 * Divide the ring buffer data size (which is 1 page less

@@ -1736,12 +1807,28 @@ static int __init storvsc_drv_init(void)
 		vmscsi_size_delta,
 		sizeof(u64)));
 
-	return vmbus_driver_register(&storvsc_drv);
+#ifdef CONFIG_SCSI_FC_ATTRS
+	fc_transport_template = fc_attach_transport(&fc_transport_functions);
+	if (!fc_transport_template)
+		return -ENODEV;
+#endif
+
+	ret = vmbus_driver_register(&storvsc_drv);
+
+#ifdef CONFIG_SCSI_FC_ATTRS
+	if (ret)
+		fc_release_transport(fc_transport_template);
+#endif
+
+	return ret;
 }
 
 static void __exit storvsc_drv_exit(void)
 {
 	vmbus_driver_unregister(&storvsc_drv);
+#ifdef CONFIG_SCSI_FC_ATTRS
+	fc_release_transport(fc_transport_template);
+#endif
 }
 
 MODULE_LICENSE("GPL");

Signature · 1 line

1.7.4.1

Hannes Reinecke

2015-12-18 08:49 UTC #3 lore raw

Re: [PATCH V3 2/4] scsi: storvsc: Properly support Fibre Channel devices

Quoted 356 lines · K. Y. Srinivasan

Signed-off-by K. Y. Srinivasan <[email protected]>

Reviewed-by Long Li <[email protected]>

Tested-by Alex Ng <[email protected]>

---
V2: Fixed error paths - Dan Carpenter <[email protected]>
V3: Fixed build issues reported by kbuild test robot <[email protected]>

  drivers/scsi/storvsc_drv.c |  181 ++++++++++++++++++++++++++++++++-----------
  1 files changed, 134 insertions(+), 47 deletions(-)

drivers/scsi/storvsc_drv.c +131 ~~-47~~

index 00bb4bd..220b794 100644
@@ -41,6 +41,7 @@
  #include <scsi/scsi_eh.h>
  #include <scsi/scsi_devinfo.h>
  #include <scsi/scsi_dbg.h>
+#include <scsi/scsi_transport_fc.h>
 
  /*
   * All wire protocol details (storage protocol between the guest and the host)

@@ -397,6 +398,9 @@ static int storvsc_timeout = 180;
 
  static int msft_blist_flags = BLIST_TRY_VPD_PAGES;
 
+#ifdef CONFIG_SCSI_FC_ATTRS
+static struct scsi_transport_template *fc_transport_template;
+#endif
 
  static void storvsc_on_channel_callback(void *context);

@@ -456,6 +460,11 @@ struct storvsc_device {
  	/* Used for vsc/vsp channel reset process */
  	struct storvsc_cmd_request init_request;
  	struct storvsc_cmd_request reset_request;
+	/*
+	 * Currently active port and node names for FC devices.
+	 */
+	u64 node_name;
+	u64 port_name;
  };
 
  struct hv_host_device {

@@ -695,7 +704,26 @@ static void  handle_multichannel_storage(struct hv_device *device, int max_chns)
  	vmbus_are_subchannels_present(device->channel);
  }
 
-static int storvsc_channel_init(struct hv_device *device)
+static void cache_wwn(struct storvsc_device *stor_device,
+		      struct vstor_packet *vstor_packet)
+{
+	/*
+	 * Cache the currently active port and node ww names.
+	 */
+	if (vstor_packet->wwn_packet.primary_active) {
+		stor_device->node_name =
+			wwn_to_u64(vstor_packet->wwn_packet.primary_node_wwn);
+		stor_device->port_name =
+			wwn_to_u64(vstor_packet->wwn_packet.primary_port_wwn);
+	} else {
+		stor_device->node_name =
+			wwn_to_u64(vstor_packet->wwn_packet.secondary_node_wwn);
+		stor_device->port_name =
+			wwn_to_u64(vstor_packet->wwn_packet.secondary_port_wwn);
+	}
+}
+
+static int storvsc_channel_init(struct hv_device *device, bool is_fc)
  {
  	struct storvsc_device *stor_device;
  	struct storvsc_cmd_request *request;

@@ -727,19 +755,15 @@ static int storvsc_channel_init(struct hv_device *device)
  			       VM_PKT_DATA_INBAND,
  			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
  	if (ret != 0)
-		goto cleanup;
+		return ret;
 
  	t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
-	if (t == 0) {
-		ret = -ETIMEDOUT;
-		goto cleanup;
-	}
+	if (t == 0)
+		return -ETIMEDOUT;
 
  	if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO ||
-	    vstor_packet->status != 0) {
-		ret = -EINVAL;
-		goto cleanup;
-	}
+	    vstor_packet->status != 0)
+		return -EINVAL;
 
 
  	for (i = 0; i < ARRAY_SIZE(vmstor_protocols); i++) {

@@ -764,18 +788,14 @@ static int storvsc_channel_init(struct hv_device *device)
  			       VM_PKT_DATA_INBAND,
  			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
  		if (ret != 0)
-			goto cleanup;
+			return ret;
 
  		t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
-		if (t == 0) {
-			ret = -ETIMEDOUT;
-			goto cleanup;
-		}
+		if (t == 0)
+			return -ETIMEDOUT;
 
-		if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO) {
-			ret = -EINVAL;
-			goto cleanup;
-		}
+		if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO)
+			return -EINVAL;
 
  		if (vstor_packet->status == 0) {
  			vmstor_proto_version =

@@ -791,10 +811,8 @@ static int storvsc_channel_init(struct hv_device *device)
  		}
  	}
 
-	if (vstor_packet->status != 0) {
-		ret = -EINVAL;
-		goto cleanup;
-	}
+	if (vstor_packet->status != 0)
+		return -EINVAL;
 
 
  	memset(vstor_packet, 0, sizeof(struct vstor_packet));

@@ -809,19 +827,15 @@ static int storvsc_channel_init(struct hv_device *device)
  			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
 
  	if (ret != 0)
-		goto cleanup;
+		return ret;
 
  	t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
-	if (t == 0) {
-		ret = -ETIMEDOUT;
-		goto cleanup;
-	}
+	if (t == 0)
+		return -ETIMEDOUT;
 
  	if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO ||
-	    vstor_packet->status != 0) {
-		ret = -EINVAL;
-		goto cleanup;
-	}
+	    vstor_packet->status != 0)
+		return -EINVAL;
 
  	/*
  	 * Check to see if multi-channel support is there.

@@ -837,6 +851,38 @@ static int storvsc_channel_init(struct hv_device *device)
  	stor_device->max_transfer_bytes =
  		vstor_packet->storage_channel_properties.max_transfer_bytes;
 
+	if (!is_fc)
+		goto done;
+
+	memset(vstor_packet, 0, sizeof(struct vstor_packet));
+	vstor_packet->operation = VSTOR_OPERATION_FCHBA_DATA;
+	vstor_packet->flags = REQUEST_COMPLETION_FLAG;
+
+	ret = vmbus_sendpacket(device->channel, vstor_packet,
+			       (sizeof(struct vstor_packet) -
+			       vmscsi_size_delta),
+			       (unsigned long)request,
+			       VM_PKT_DATA_INBAND,
+			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
+
+	if (ret != 0)
+		return ret;
+
+	t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
+	if (t == 0)
+		return -ETIMEDOUT;
+
+	if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO ||
+	    vstor_packet->status != 0)
+		return -EINVAL;
+
+	/*
+	 * Cache the currently active port and node ww names.
+	 */
+	cache_wwn(stor_device, vstor_packet);
+
+done:
+
  	memset(vstor_packet, 0, sizeof(struct vstor_packet));
  	vstor_packet->operation = VSTOR_OPERATION_END_INITIALIZATION;
  	vstor_packet->flags = REQUEST_COMPLETION_FLAG;

@@ -849,25 +895,19 @@ static int storvsc_channel_init(struct hv_device *device)
  			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
 
  	if (ret != 0)
-		goto cleanup;
+		return ret;
 
  	t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
-	if (t == 0) {
-		ret = -ETIMEDOUT;
-		goto cleanup;
-	}
+	if (t == 0)
+		return -ETIMEDOUT;
 
  	if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO ||
-	    vstor_packet->status != 0) {
-		ret = -EINVAL;
-		goto cleanup;
-	}
+	    vstor_packet->status != 0)
+		return -EINVAL;
 
  	if (process_sub_channels)
  		handle_multichannel_storage(device, max_chns);
 
-
-cleanup:
  	return ret;
  }

@@ -1076,6 +1116,14 @@ static void storvsc_on_receive(struct hv_device *device,
  		schedule_work(&work->work);
  		break;
 
+	case VSTOR_OPERATION_FCHBA_DATA:
+		stor_device = get_in_stor_device(device);
+		cache_wwn(stor_device, vstor_packet);
+#ifdef CONFIG_SCSI_FC_ATTRS
+		fc_host_node_name(stor_device->host) = stor_device->node_name;
+		fc_host_port_name(stor_device->host) = stor_device->port_name;
+#endif
+		break;
  	default:
  		break;
  	}

@@ -1131,7 +1179,8 @@ static void storvsc_on_channel_callback(void *context)
  	return;
  }
 
-static int storvsc_connect_to_vsp(struct hv_device *device, u32 ring_size)
+static int storvsc_connect_to_vsp(struct hv_device *device, u32 ring_size,
+				  bool is_fc)
  {
  	struct vmstorage_channel_properties props;
  	int ret;

@@ -1148,7 +1197,7 @@ static int storvsc_connect_to_vsp(struct hv_device *device, u32 ring_size)
  	if (ret != 0)
  		return ret;
 
-	ret = storvsc_channel_init(device);
+	ret = storvsc_channel_init(device, is_fc);
 
  	return ret;
  }

@@ -1573,6 +1622,7 @@ static int storvsc_probe(struct hv_device *device,
  	struct Scsi_Host *host;
  	struct hv_host_device *host_dev;
  	bool dev_is_ide = ((dev_id->driver_data == IDE_GUID) ? true : false);
+	bool is_fc = ((dev_id->driver_data == SFC_GUID) ? true : false);
  	int target = 0;
  	struct storvsc_device *stor_device;
  	int max_luns_per_target;

@@ -1630,7 +1680,7 @@ static int storvsc_probe(struct hv_device *device,
  	hv_set_drvdata(device, stor_device);
 
  	stor_device->port_number = host->host_no;
-	ret = storvsc_connect_to_vsp(device, storvsc_ringbuffer_size);
+	ret = storvsc_connect_to_vsp(device, storvsc_ringbuffer_size, is_fc);
  	if (ret)
  		goto err_out1;

@@ -1642,6 +1692,9 @@ static int storvsc_probe(struct hv_device *device,
  		host->max_lun = STORVSC_FC_MAX_LUNS_PER_TARGET;
  		host->max_id = STORVSC_FC_MAX_TARGETS;
  		host->max_channel = STORVSC_FC_MAX_CHANNELS - 1;
+#ifdef CONFIG_SCSI_FC_ATTRS
+		host->transportt = fc_transport_template;
+#endif
  		break;
 
  	case SCSI_GUID:

@@ -1681,6 +1734,12 @@ static int storvsc_probe(struct hv_device *device,
  			goto err_out2;
  		}
  	}
+#ifdef CONFIG_SCSI_FC_ATTRS
+	if (host->transportt == fc_transport_template) {
+		fc_host_node_name(host) = stor_device->node_name;
+		fc_host_port_name(host) = stor_device->port_name;
+	}
+#endif
  	return 0;
 
  err_out2:

@@ -1706,6 +1765,10 @@ static int storvsc_remove(struct hv_device *dev)
  	struct storvsc_device *stor_device = hv_get_drvdata(dev);
  	struct Scsi_Host *host = stor_device->host;
 
+#ifdef CONFIG_SCSI_FC_ATTRS
+	if (host->transportt == fc_transport_template)
+		fc_remove_host(host);
+#endif
  	scsi_remove_host(host);
  	storvsc_dev_remove(dev);
  	scsi_host_put(host);

@@ -1720,8 +1783,16 @@ static struct hv_driver storvsc_drv = {
  	.remove = storvsc_remove,
  };
 
+#ifdef CONFIG_SCSI_FC_ATTRS
+static struct fc_function_template fc_transport_functions = {
+	.show_host_node_name = 1,
+	.show_host_port_name = 1,
+};
+#endif
+
  static int __init storvsc_drv_init(void)
  {
+	int ret;
 
  	/*
  	 * Divide the ring buffer data size (which is 1 page less

@@ -1736,12 +1807,28 @@ static int __init storvsc_drv_init(void)
  		vmscsi_size_delta,
  		sizeof(u64)));
 
-	return vmbus_driver_register(&storvsc_drv);
+#ifdef CONFIG_SCSI_FC_ATTRS
+	fc_transport_template = fc_attach_transport(&fc_transport_functions);
+	if (!fc_transport_template)
+		return -ENODEV;
+#endif
+
+	ret = vmbus_driver_register(&storvsc_drv);
+
+#ifdef CONFIG_SCSI_FC_ATTRS
+	if (ret)
+		fc_release_transport(fc_transport_template);
+#endif
+
+	return ret;
  }

drivers/scsi/storvsc_drv.c static int __init storvsc_drv_init(void) · line 1834

Quoted 10 lines

drivers/scsi/storvsc_drv.c +3 -0

 
  static void __exit storvsc_drv_exit(void)
  {
  	vmbus_driver_unregister(&storvsc_drv);
+#ifdef CONFIG_SCSI_FC_ATTRS
+	fc_release_transport(fc_transport_template);
+#endif
  }
 
  MODULE_LICENSE("GPL");

Well.
This would _always_ attach the FC template to the storvsc driver, even if it not used. Typically one would be using a separate driver for that, but hey.

_However_: How should you handle FC attached devices if the FC transport template is _NOT_ selected? By rights one would expect the driver to not handle those devices; but looking at the code this doesn't happen.

What I would like to see is a clear separation here:
- Disable FC disk handling if FC attributes are not configured
- Add a module parameter allowing to disable FC attributes even if they are compiled in. Remember: this is a virtualized guest, and people might want so save kernel memory wherever they can. So always attaching to the fc transport template will make them very unhappy. Alternatively you could split out FC device handling into a separate driver, but seeing the diff that's probably overkill.

Cheers,

Hannes

Signature · 5 lines

Dr. Hannes Reinecke		               zSeries & Storage
[email protected]			               +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG Nürnberg)

KY Srinivasan

author

2015-12-18 17:13 UTC #4 lore raw

RE: [PATCH V3 2/4] scsi: storvsc: Properly support Fibre Channel devices

Quoted 426 lines

-----Original Message-----
From: Hannes Reinecke [mailto:[email protected]]
Sent: Friday, December 18, 2015 12:49 AM
To: KY Srinivasan <[email protected]>; [email protected]; linux- [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]
Subject: Re: [PATCH V3 2/4] scsi: storvsc: Properly support Fibre Channel devices
Quoted 3 lines · K. Y. Srinivasan
For FC devices managed by this driver, atttach the appropriate transport template. This will allow us to create the appropriate sysfs files for these devices. With this we can publish the wwn for both the port and the
node.
Quoted 9 lines
Signed-off-by K. Y. Srinivasan <[email protected]>
Reviewed-by Long Li <[email protected]>
Tested-by Alex Ng <[email protected]>
---
V2: Fixed error paths - Dan Carpenter <[email protected]>
V3: Fixed build issues reported by kbuild test robot <[email protected]>
  drivers/scsi/storvsc_drv.c |  181
++++++++++++++++++++++++++++++++-----------
Quoted 7 lines
  1 files changed, 134 insertions(+), 47 deletions(-)
drivers/scsi/storvsc_drv.c +0 -0
index 00bb4bd..220b794 100644
drivers/scsi/storvsc_drv.c line 47
Quoted 7 lines
drivers/scsi/storvsc_drv.c +1 -0
@@ -41,6 +41,7 @@
  #include <scsi/scsi_eh.h>
  #include <scsi/scsi_devinfo.h>
  #include <scsi/scsi_dbg.h>
+#include <scsi/scsi_transport_fc.h>
 
  /*
   * All wire protocol details (storage protocol between the guest and the
host)
drivers/scsi/storvsc_drv.c static void handle_multichannel_storage(struct
Quoted 23 lines
drivers/scsi/storvsc_drv.c +8 -0
@@ -397,6 +398,9 @@ static int storvsc_timeout = 180;
 
  static int msft_blist_flags = BLIST_TRY_VPD_PAGES;
 
+#ifdef CONFIG_SCSI_FC_ATTRS
+static struct scsi_transport_template *fc_transport_template;
+#endif
 
  static void storvsc_on_channel_callback(void *context);
 
@@ -456,6 +460,11 @@ struct storvsc_device {
  	/* Used for vsc/vsp channel reset process */
  	struct storvsc_cmd_request init_request;
  	struct storvsc_cmd_request reset_request;
+	/*
+	 * Currently active port and node names for FC devices.
+	 */
+	u64 node_name;
+	u64 port_name;
  };
 
  struct hv_host_device {
@@ -695,7 +704,26 @@ static void  handle_multichannel_storage(struct
hv_device *device, int max_chns)
drivers/scsi/storvsc_drv.c static int storvsc_channel_init(struct hv_device
Quoted 32 lines
drivers/scsi/storvsc_drv.c +16 -1
  	vmbus_are_subchannels_present(device->channel);
  }
 
-static int storvsc_channel_init(struct hv_device *device)
+static void cache_wwn(struct storvsc_device *stor_device,
+		      struct vstor_packet *vstor_packet)
+{
+	/*
+	 * Cache the currently active port and node ww names.
+	 */
+	if (vstor_packet->wwn_packet.primary_active) {
+		stor_device->node_name =
+			wwn_to_u64(vstor_packet-
 wwn_packet.primary_node_wwn);
+		stor_device->port_name =
+			wwn_to_u64(vstor_packet-
 wwn_packet.primary_port_wwn);
+	} else {
+		stor_device->node_name =
+			wwn_to_u64(vstor_packet-
 wwn_packet.secondary_node_wwn);
+		stor_device->port_name =
+			wwn_to_u64(vstor_packet-
wwn_packet.secondary_port_wwn);
drivers/scsi/storvsc_drv.c +4 -0
+	}
+}
+
+static int storvsc_channel_init(struct hv_device *device, bool is_fc)
  {
  	struct storvsc_device *stor_device;
  	struct storvsc_cmd_request *request;
@@ -727,19 +755,15 @@ static int storvsc_channel_init(struct hv_device
*device)
drivers/scsi/storvsc_drv.c static int storvsc_channel_init(struct hv_device · line 756
Quoted 2 lines
drivers/scsi/storvsc_drv.c +0 -0
  			       VM_PKT_DATA_INBAND,
 
VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
drivers/scsi/storvsc_drv.c static int storvsc_channel_init(struct hv_device *device)
Quoted 13 lines
drivers/scsi/storvsc_drv.c +3 -5
  	if (ret != 0)
-		goto cleanup;
+		return ret;
 
  	t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
-	if (t == 0) {
-		ret = -ETIMEDOUT;
-		goto cleanup;
-	}
+	if (t == 0)
+		return -ETIMEDOUT;
 
  	if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO
||
> -	    vstor_packet->status != 0) {
drivers/scsi/storvsc_drv.c static int storvsc_channel_init(struct hv_device
Quoted 9 lines
drivers/scsi/storvsc_drv.c +2 -3
-		ret = -EINVAL;
-		goto cleanup;
-	}
+	    vstor_packet->status != 0)
+		return -EINVAL;
 
 
  	for (i = 0; i < ARRAY_SIZE(vmstor_protocols); i++) {
@@ -764,18 +788,14 @@ static int storvsc_channel_init(struct hv_device
*device)
drivers/scsi/storvsc_drv.c static int storvsc_channel_init(struct hv_device · line 789
Quoted 2 lines
drivers/scsi/storvsc_drv.c +0 -0
  			       VM_PKT_DATA_INBAND,
 
VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
drivers/scsi/storvsc_drv.c static int storvsc_channel_init(struct hv_device *device)
Quoted 5 lines
drivers/scsi/storvsc_drv.c +1 -1
  		if (ret != 0)
-			goto cleanup;
+			return ret;
 
  		t = wait_for_completion_timeout(&request->wait_event,
5*HZ);
drivers/scsi/storvsc_drv.c static int storvsc_channel_init(struct hv_device *device)
Quoted 8 lines
drivers/scsi/storvsc_drv.c +2 -5
-		if (t == 0) {
-			ret = -ETIMEDOUT;
-			goto cleanup;
-		}
+		if (t == 0)
+			return -ETIMEDOUT;
 
-		if (vstor_packet->operation !=
VSTOR_OPERATION_COMPLETE_IO) {
drivers/scsi/storvsc_drv.c static int storvsc_channel_init(struct hv_device *device)
Quoted 4 lines
drivers/scsi/storvsc_drv.c +1 -3
-			ret = -EINVAL;
-			goto cleanup;
-		}
+		if (vstor_packet->operation !=
VSTOR_OPERATION_COMPLETE_IO)
drivers/scsi/storvsc_drv.c static int storvsc_channel_init(struct hv_device
Quoted 5 lines
drivers/scsi/storvsc_drv.c +1 -0
+			return -EINVAL;
 
  		if (vstor_packet->status == 0) {
  			vmstor_proto_version =
@@ -791,10 +811,8 @@ static int storvsc_channel_init(struct hv_device
*device)
drivers/scsi/storvsc_drv.c static int storvsc_channel_init(struct hv_device
Quoted 13 lines
drivers/scsi/storvsc_drv.c +2 -4
  		}
  	}
 
-	if (vstor_packet->status != 0) {
-		ret = -EINVAL;
-		goto cleanup;
-	}
+	if (vstor_packet->status != 0)
+		return -EINVAL;
 
 
  	memset(vstor_packet, 0, sizeof(struct vstor_packet));
@@ -809,19 +827,15 @@ static int storvsc_channel_init(struct hv_device
*device)
Quoted 1 line
VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
Quoted 4 lines
if (ret != 0)
drivers/scsi/storvsc_drv.c +1 -1
-		goto cleanup;
+		return ret;
drivers/scsi/storvsc_drv.c static int storvsc_channel_init(struct hv_device *device)
Quoted 10 lines
drivers/scsi/storvsc_drv.c +2 -4
 
  	t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
-	if (t == 0) {
-		ret = -ETIMEDOUT;
-		goto cleanup;
-	}
+	if (t == 0)
+		return -ETIMEDOUT;
 
  	if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO
||
> -	    vstor_packet->status != 0) {
drivers/scsi/storvsc_drv.c static int storvsc_channel_init(struct hv_device
Quoted 9 lines
drivers/scsi/storvsc_drv.c +2 -3
-		ret = -EINVAL;
-		goto cleanup;
-	}
+	    vstor_packet->status != 0)
+		return -EINVAL;
 
  	/*
  	 * Check to see if multi-channel support is there.
@@ -837,6 +851,38 @@ static int storvsc_channel_init(struct hv_device
*device)
Quoted 7 lines
drivers/scsi/storvsc_drv.c +3 -0
  	stor_device->max_transfer_bytes =
  		vstor_packet-
 storage_channel_properties.max_transfer_bytes;
 
+	if (!is_fc)
+		goto done;
+
drivers/scsi/storvsc_drv.c static int storvsc_channel_init(struct hv_device *device) · line 867
Quoted 10 lines
drivers/scsi/storvsc_drv.c +10 -0
+	memset(vstor_packet, 0, sizeof(struct vstor_packet));
+	vstor_packet->operation = VSTOR_OPERATION_FCHBA_DATA;
+	vstor_packet->flags = REQUEST_COMPLETION_FLAG;
+
+	ret = vmbus_sendpacket(device->channel, vstor_packet,
+			       (sizeof(struct vstor_packet) -
+			       vmscsi_size_delta),
+			       (unsigned long)request,
+			       VM_PKT_DATA_INBAND,
+
VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
drivers/scsi/storvsc_drv.c static int storvsc_channel_init(struct hv_device *device)
Quoted 9 lines
drivers/scsi/storvsc_drv.c +9 -0
+
+	if (ret != 0)
+		return ret;
+
+	t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
+	if (t == 0)
+		return -ETIMEDOUT;
+
+	if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO
||
> +	    vstor_packet->status != 0)
drivers/scsi/storvsc_drv.c static int storvsc_channel_init(struct hv_device *device)
Quoted 11 lines
drivers/scsi/storvsc_drv.c +9 -0
+		return -EINVAL;
+
+	/*
+	 * Cache the currently active port and node ww names.
+	 */
+	cache_wwn(stor_device, vstor_packet);
+
+done:
+
  	memset(vstor_packet, 0, sizeof(struct vstor_packet));
  	vstor_packet->operation =
VSTOR_OPERATION_END_INITIALIZATION;
drivers/scsi/storvsc_drv.c static int storvsc_channel_init(struct hv_device
Quoted 2 lines
drivers/scsi/storvsc_drv.c +0 -0
  	vstor_packet->flags = REQUEST_COMPLETION_FLAG;
@@ -849,25 +895,19 @@ static int storvsc_channel_init(struct hv_device
*device)
Quoted 1 line
VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
Quoted 4 lines
if (ret != 0)
drivers/scsi/storvsc_drv.c +1 -1
-		goto cleanup;
+		return ret;
drivers/scsi/storvsc_drv.c static int storvsc_channel_init(struct hv_device *device)
Quoted 10 lines
drivers/scsi/storvsc_drv.c +2 -4
 
  	t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
-	if (t == 0) {
-		ret = -ETIMEDOUT;
-		goto cleanup;
-	}
+	if (t == 0)
+		return -ETIMEDOUT;
 
  	if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO
||
> -	    vstor_packet->status != 0) {
drivers/scsi/storvsc_drv.c static void storvsc_on_receive(struct hv_device
Quoted 15 lines
drivers/scsi/storvsc_drv.c +2 -5
-		ret = -EINVAL;
-		goto cleanup;
-	}
+	    vstor_packet->status != 0)
+		return -EINVAL;
 
  	if (process_sub_channels)
  		handle_multichannel_storage(device, max_chns);
 
-
-cleanup:
  	return ret;
  }
@@ -1076,6 +1116,14 @@ static void storvsc_on_receive(struct hv_device
*device,
drivers/scsi/storvsc_drv.c static void storvsc_on_channel_callback(void
Quoted 17 lines
drivers/scsi/storvsc_drv.c +8 -0
  		schedule_work(&work->work);
  		break;
 
+	case VSTOR_OPERATION_FCHBA_DATA:
+		stor_device = get_in_stor_device(device);
+		cache_wwn(stor_device, vstor_packet);
+#ifdef CONFIG_SCSI_FC_ATTRS
+		fc_host_node_name(stor_device->host) = stor_device-
 node_name;
+		fc_host_port_name(stor_device->host) = stor_device-
 port_name;
+#endif
+		break;
  	default:
  		break;
  	}
drivers/scsi/storvsc_drv.c +0 -0
@@ -1131,7 +1179,8 @@ static void storvsc_on_channel_callback(void
*context)
drivers/scsi/storvsc_drv.c static int storvsc_connect_to_vsp(struct
Quoted 10 lines
drivers/scsi/storvsc_drv.c +2 -1
  	return;
  }
 
-static int storvsc_connect_to_vsp(struct hv_device *device, u32 ring_size)
+static int storvsc_connect_to_vsp(struct hv_device *device, u32 ring_size,
+				  bool is_fc)
  {
  	struct vmstorage_channel_properties props;
  	int ret;
@@ -1148,7 +1197,7 @@ static int storvsc_connect_to_vsp(struct
hv_device *device, u32 ring_size)
drivers/scsi/storvsc_drv.c static int storvsc_probe(struct hv_device
Quoted 36 lines
drivers/scsi/storvsc_drv.c +6 -2
  	if (ret != 0)
  		return ret;
 
-	ret = storvsc_channel_init(device);
+	ret = storvsc_channel_init(device, is_fc);
 
  	return ret;
  }
@@ -1573,6 +1622,7 @@ static int storvsc_probe(struct hv_device *device,
  	struct Scsi_Host *host;
  	struct hv_host_device *host_dev;
  	bool dev_is_ide = ((dev_id->driver_data == IDE_GUID) ? true : false);
+	bool is_fc = ((dev_id->driver_data == SFC_GUID) ? true : false);
  	int target = 0;
  	struct storvsc_device *stor_device;
  	int max_luns_per_target;
@@ -1630,7 +1680,7 @@ static int storvsc_probe(struct hv_device *device,
  	hv_set_drvdata(device, stor_device);
 
  	stor_device->port_number = host->host_no;
-	ret = storvsc_connect_to_vsp(device, storvsc_ringbuffer_size);
+	ret = storvsc_connect_to_vsp(device, storvsc_ringbuffer_size, is_fc);
  	if (ret)
  		goto err_out1;
 
@@ -1642,6 +1692,9 @@ static int storvsc_probe(struct hv_device *device,
  		host->max_lun = STORVSC_FC_MAX_LUNS_PER_TARGET;
  		host->max_id = STORVSC_FC_MAX_TARGETS;
  		host->max_channel = STORVSC_FC_MAX_CHANNELS - 1;
+#ifdef CONFIG_SCSI_FC_ATTRS
+		host->transportt = fc_transport_template;
+#endif
  		break;
 
  	case SCSI_GUID:
@@ -1681,6 +1734,12 @@ static int storvsc_probe(struct hv_device
*device,
drivers/scsi/storvsc_drv.c static int storvsc_remove(struct hv_device
Quoted 13 lines
drivers/scsi/storvsc_drv.c +6 -0
  			goto err_out2;
  		}
  	}
+#ifdef CONFIG_SCSI_FC_ATTRS
+	if (host->transportt == fc_transport_template) {
+		fc_host_node_name(host) = stor_device->node_name;
+		fc_host_port_name(host) = stor_device->port_name;
+	}
+#endif
  	return 0;
 
  err_out2:
@@ -1706,6 +1765,10 @@ static int storvsc_remove(struct hv_device
*dev)
Quoted 28 lines
drivers/scsi/storvsc_drv.c +12 -0
  	struct storvsc_device *stor_device = hv_get_drvdata(dev);
  	struct Scsi_Host *host = stor_device->host;
 
+#ifdef CONFIG_SCSI_FC_ATTRS
+	if (host->transportt == fc_transport_template)
+		fc_remove_host(host);
+#endif
  	scsi_remove_host(host);
  	storvsc_dev_remove(dev);
  	scsi_host_put(host);
@@ -1720,8 +1783,16 @@ static struct hv_driver storvsc_drv = {
  	.remove = storvsc_remove,
  };
 
+#ifdef CONFIG_SCSI_FC_ATTRS
+static struct fc_function_template fc_transport_functions = {
+	.show_host_node_name = 1,
+	.show_host_port_name = 1,
+};
+#endif
+
  static int __init storvsc_drv_init(void)
  {
+	int ret;
 
  	/*
  	 * Divide the ring buffer data size (which is 1 page less
drivers/scsi/storvsc_drv.c static int __init storvsc_drv_init(void) · line 1811
Quoted 6 lines
drivers/scsi/storvsc_drv.c +2 -1
@@ -1736,12 +1807,28 @@ static int __init storvsc_drv_init(void)
  		vmscsi_size_delta,
  		sizeof(u64)));
 
-	return vmbus_driver_register(&storvsc_drv);
+#ifdef CONFIG_SCSI_FC_ATTRS
+	fc_transport_template =
fc_attach_transport(&fc_transport_functions);
Quoted 14 lines
drivers/scsi/storvsc_drv.c +12 -0
+	if (!fc_transport_template)
+		return -ENODEV;
+#endif
+
+	ret = vmbus_driver_register(&storvsc_drv);
+
+#ifdef CONFIG_SCSI_FC_ATTRS
+	if (ret)
+		fc_release_transport(fc_transport_template);
+#endif
+
+	return ret;
  }
drivers/scsi/storvsc_drv.c static int __init storvsc_drv_init(void) · line 1834
Quoted 10 lines
drivers/scsi/storvsc_drv.c +3 -0
 
  static void __exit storvsc_drv_exit(void)
  {
  	vmbus_driver_unregister(&storvsc_drv);
+#ifdef CONFIG_SCSI_FC_ATTRS
+	fc_release_transport(fc_transport_template);
+#endif
  }
 
  MODULE_LICENSE("GPL");
Well.
This would _always_ attach the FC template to the storvsc driver, even if it not used. Typically one would be using a separate driver for that, but hey.
_However_: How should you handle FC attached devices if the FC transport template is _NOT_ selected?
By rights one would expect the driver to not handle those devices; but looking at the code this doesn't happen.

Quoted 8 lines

What I would like to see is a clear separation here:
- Disable FC disk handling if FC attributes are not configured
- Add a module parameter allowing to disable FC attributes even if they are compiled in. Remember: this is a virtualized guest, and people might want so save kernel memory wherever they can. So always attaching to the fc transport template will make them very unhappy. Alternatively you could split out FC device handling into a separate driver, but seeing the diff that's probably overkill.

Hannes,
Another option might be to allocate the FC transport template in the probe call when we are presented with a FC device (this would still be under the appropriate config option). This way, when no FC device is configured for the guest, we don't allocate FC transport template.

Regards,

K. Y

Quoted 10 lines

Cheers,
Hannes
--
Dr. Hannes Reinecke zSeries & Storage
[email protected] +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton HRB 21284 (AG Nürnberg)

James Bottomley

maintainer

2015-12-18 17:13 UTC #5 lore raw

Re: [PATCH V3 2/4] scsi: storvsc: Properly support Fibre Channel devices

In reply to Hannes Reinecke

Quoted 8 lines · Hannes Reinecke

What I would like to see is a clear separation here:
- Disable FC disk handling if FC attributes are not configured
- Add a module parameter allowing to disable FC attributes even if they are compiled in. Remember: this is a virtualized guest, and people might want so save kernel memory wherever they can. So always attaching to the fc transport template will make them very unhappy. Alternatively you could split out FC device handling into a separate driver, but seeing the diff that's probably overkill.

I don't quite see how this can be a module parameter: the fc_transport_class is pulled in by symbol references. They won't go away whether a module parameter is zero or one. The only way to get the module not to link with a transport class is to have it not use the symbols at compile time (either because they're surrounded by an #ifdef or with an if() which the compiler evaluates at compile time to zero).
In userspace you get around this with introspection and dlopen, but I
don't think we have that functionality in the kernel.

James

KY Srinivasan

author

2015-12-21 16:02 UTC #6 lore raw

RE: [PATCH V3 2/4] scsi: storvsc: Properly support Fibre Channel devices

Quoted 24 lines

-----Original Message-----
From: James Bottomley [mailto:[email protected]]
Sent: Friday, December 18, 2015 9:14 AM
To: Hannes Reinecke <[email protected]>; KY Srinivasan <[email protected]>; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]
Subject: Re: [PATCH V3 2/4] scsi: storvsc: Properly support Fibre Channel devices
Quoted 8 lines · Hannes Reinecke
What I would like to see is a clear separation here:
- Disable FC disk handling if FC attributes are not configured
- Add a module parameter allowing to disable FC attributes even if they are compiled in. Remember: this is a virtualized guest, and people might want so save kernel memory wherever they can. So always attaching to the fc transport template will make them very unhappy. Alternatively you could split out FC device handling into a separate driver, but seeing the diff that's probably overkill.

Quoted 8 lines

I don't quite see how this can be a module parameter: the fc_transport_class is pulled in by symbol references. They won't go away whether a module parameter is zero or one. The only way to get the module not to link with a transport class is to have it not use the symbols at compile time (either because they're surrounded by an #ifdef or with an if() which the compiler evaluates at compile time to zero).
In userspace you get around this with introspection and dlopen, but I
don't think we have that functionality in the kernel.

Hannes,
Perhaps I misunderstood your comment when I first responded to this suggestion from you - I thought you were concerned about unconditionally allocating FC transport template and I had proposed a work around that. Now looking at James comment, it looks like you were concerned about FC transport module dependency on the storvsc module. Do you still want me to work on my proposal.

Thanks,

K. Y

Quoted 2 lines

James

K. Y. Srinivasan

author

2015-12-13 18:55 UTC #7 lore raw

PATCH v3 3/4 scsi: storvsc: Refactor the code in storvsc_channel_init()

In reply to K. Y. Srinivasan

The function storvsc_channel_init() repeatedly interacts with the host to extract various channel properties. Refactor this code to eliminate code repetition.

Signed-off-by K. Y. Srinivasan <[email protected]>

Reviewed-by Long Li <[email protected]>

Reviewed-by Johannes Thumshirn <[email protected]>

Tested-by Alex Ng <[email protected]>

---
V2: Fixed error paths - Dan Carpenter <[email protected]>

 drivers/scsi/storvsc_drv.c |  126 ++++++++++++++++----------------------------
 1 files changed, 46 insertions(+), 80 deletions(-)

drivers/scsi/storvsc_drv.c +46 ~~-80~~

index 220b794..d6ca4f2 100644
@@ -723,29 +723,17 @@ static void cache_wwn(struct storvsc_device *stor_device,
 	}
 }
 
-static int storvsc_channel_init(struct hv_device *device, bool is_fc)
+
+static int storvsc_execute_vstor_op(struct hv_device *device,
+				    struct storvsc_cmd_request *request,
+				    bool status_check)
 {
-	struct storvsc_device *stor_device;
-	struct storvsc_cmd_request *request;
 	struct vstor_packet *vstor_packet;
-	int ret, t, i;
-	int max_chns;
-	bool process_sub_channels = false;
-
-	stor_device = get_out_stor_device(device);
-	if (!stor_device)
-		return -ENODEV;
+	int ret, t;
 
-	request = &stor_device->init_request;
 	vstor_packet = &request->vstor_packet;
 
-	/*
-	 * Now, initiate the vsc/vsp initialization protocol on the open
-	 * channel
-	 */
-	memset(request, 0, sizeof(struct storvsc_cmd_request));
 	init_completion(&request->wait_event);
-	vstor_packet->operation = VSTOR_OPERATION_BEGIN_INITIALIZATION;
 	vstor_packet->flags = REQUEST_COMPLETION_FLAG;
 
 	ret = vmbus_sendpacket(device->channel, vstor_packet,

@@ -761,17 +749,50 @@ static int storvsc_channel_init(struct hv_device *device, bool is_fc)
 	if (t == 0)
 		return -ETIMEDOUT;
 
+	if (!status_check)
+		return ret;
+
 	if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO ||
 	    vstor_packet->status != 0)
 		return -EINVAL;
 
+	return ret;
+}
+
+static int storvsc_channel_init(struct hv_device *device, bool is_fc)
+{
+	struct storvsc_device *stor_device;
+	struct storvsc_cmd_request *request;
+	struct vstor_packet *vstor_packet;
+	int ret, i;
+	int max_chns;
+	bool process_sub_channels = false;
+
+	stor_device = get_out_stor_device(device);
+	if (!stor_device)
+		return -ENODEV;
+
+	request = &stor_device->init_request;
+	vstor_packet = &request->vstor_packet;
+
+	/*
+	 * Now, initiate the vsc/vsp initialization protocol on the open
+	 * channel
+	 */
+	memset(request, 0, sizeof(struct storvsc_cmd_request));
+	vstor_packet->operation = VSTOR_OPERATION_BEGIN_INITIALIZATION;
+	ret = storvsc_execute_vstor_op(device, request, true);
+	if (ret)
+		return ret;
+	/*
+	 * Query host supported protocol version.
+	 */
 
 	for (i = 0; i < ARRAY_SIZE(vmstor_protocols); i++) {
 		/* reuse the packet for version range supported */
 		memset(vstor_packet, 0, sizeof(struct vstor_packet));
 		vstor_packet->operation =
 			VSTOR_OPERATION_QUERY_PROTOCOL_VERSION;
-		vstor_packet->flags = REQUEST_COMPLETION_FLAG;
 
 		vstor_packet->version.major_minor =
 			vmstor_protocols[i].protocol_version;

@@ -780,20 +801,10 @@ static int storvsc_channel_init(struct hv_device *device, bool is_fc)
 		 * The revision number is only used in Windows; set it to 0.
 		 */
 		vstor_packet->version.revision = 0;
-
-		ret = vmbus_sendpacket(device->channel, vstor_packet,
-			       (sizeof(struct vstor_packet) -
-				vmscsi_size_delta),
-			       (unsigned long)request,
-			       VM_PKT_DATA_INBAND,
-			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
+		ret = storvsc_execute_vstor_op(device, request, false);
 		if (ret != 0)
 			return ret;
 
-		t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
-		if (t == 0)
-			return -ETIMEDOUT;
-
 		if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO)
 			return -EINVAL;

@@ -817,26 +828,10 @@ static int storvsc_channel_init(struct hv_device *device, bool is_fc)
 
 	memset(vstor_packet, 0, sizeof(struct vstor_packet));
 	vstor_packet->operation = VSTOR_OPERATION_QUERY_PROPERTIES;
-	vstor_packet->flags = REQUEST_COMPLETION_FLAG;
-
-	ret = vmbus_sendpacket(device->channel, vstor_packet,
-			       (sizeof(struct vstor_packet) -
-				vmscsi_size_delta),
-			       (unsigned long)request,
-			       VM_PKT_DATA_INBAND,
-			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
-
+	ret = storvsc_execute_vstor_op(device, request, true);
 	if (ret != 0)
 		return ret;
 
-	t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
-	if (t == 0)
-		return -ETIMEDOUT;
-
-	if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO ||
-	    vstor_packet->status != 0)
-		return -EINVAL;
-
 	/*
 	 * Check to see if multi-channel support is there.
 	 * Hosts that implement protocol version of 5.1 and above

@@ -854,28 +849,15 @@ static int storvsc_channel_init(struct hv_device *device, bool is_fc)
 	if (!is_fc)
 		goto done;
 
+	/*
+	 * For FC devices retrieve FC HBA data.
+	 */
 	memset(vstor_packet, 0, sizeof(struct vstor_packet));
 	vstor_packet->operation = VSTOR_OPERATION_FCHBA_DATA;
-	vstor_packet->flags = REQUEST_COMPLETION_FLAG;
-
-	ret = vmbus_sendpacket(device->channel, vstor_packet,
-			       (sizeof(struct vstor_packet) -
-			       vmscsi_size_delta),
-			       (unsigned long)request,
-			       VM_PKT_DATA_INBAND,
-			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
-
+	ret = storvsc_execute_vstor_op(device, request, true);
 	if (ret != 0)
 		return ret;
 
-	t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
-	if (t == 0)
-		return -ETIMEDOUT;
-
-	if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO ||
-	    vstor_packet->status != 0)
-		return -EINVAL;
-
 	/*
 	 * Cache the currently active port and node ww names.
 	 */

@@ -885,26 +867,10 @@ done:
 
 	memset(vstor_packet, 0, sizeof(struct vstor_packet));
 	vstor_packet->operation = VSTOR_OPERATION_END_INITIALIZATION;
-	vstor_packet->flags = REQUEST_COMPLETION_FLAG;
-
-	ret = vmbus_sendpacket(device->channel, vstor_packet,
-			       (sizeof(struct vstor_packet) -
-				vmscsi_size_delta),
-			       (unsigned long)request,
-			       VM_PKT_DATA_INBAND,
-			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
-
+	ret = storvsc_execute_vstor_op(device, request, true);
 	if (ret != 0)
 		return ret;
 
-	t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
-	if (t == 0)
-		return -ETIMEDOUT;
-
-	if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO ||
-	    vstor_packet->status != 0)
-		return -EINVAL;
-
 	if (process_sub_channels)
 		handle_multichannel_storage(device, max_chns);

Signature · 1 line

1.7.4.1

Hannes Reinecke

2015-12-18 08:50 UTC #8 lore raw

Re: [PATCH V3 3/4] scsi: storvsc: Refactor the code in storvsc_channel_init()

Quoted 207 lines · K. Y. Srinivasan

The function storvsc_channel_init() repeatedly interacts with the host to extract various channel properties. Refactor this code to eliminate code repetition.

Signed-off-by K. Y. Srinivasan <[email protected]>

Reviewed-by Long Li <[email protected]>

Reviewed-by Johannes Thumshirn <[email protected]>

Tested-by Alex Ng <[email protected]>

---
V2: Fixed error paths - Dan Carpenter <[email protected]>

  drivers/scsi/storvsc_drv.c |  126 ++++++++++++++++----------------------------
  1 files changed, 46 insertions(+), 80 deletions(-)

drivers/scsi/storvsc_drv.c +46 ~~-73~~

index 220b794..d6ca4f2 100644
@@ -723,29 +723,17 @@ static void cache_wwn(struct storvsc_device *stor_device,
  	}
  }
 
-static int storvsc_channel_init(struct hv_device *device, bool is_fc)
+
+static int storvsc_execute_vstor_op(struct hv_device *device,
+				    struct storvsc_cmd_request *request,
+				    bool status_check)
  {
-	struct storvsc_device *stor_device;
-	struct storvsc_cmd_request *request;
  	struct vstor_packet *vstor_packet;
-	int ret, t, i;
-	int max_chns;
-	bool process_sub_channels = false;
-
-	stor_device = get_out_stor_device(device);
-	if (!stor_device)
-		return -ENODEV;
+	int ret, t;
 
-	request = &stor_device->init_request;
  	vstor_packet = &request->vstor_packet;
 
-	/*
-	 * Now, initiate the vsc/vsp initialization protocol on the open
-	 * channel
-	 */
-	memset(request, 0, sizeof(struct storvsc_cmd_request));
  	init_completion(&request->wait_event);
-	vstor_packet->operation = VSTOR_OPERATION_BEGIN_INITIALIZATION;
  	vstor_packet->flags = REQUEST_COMPLETION_FLAG;
 
  	ret = vmbus_sendpacket(device->channel, vstor_packet,

@@ -761,17 +749,50 @@ static int storvsc_channel_init(struct hv_device *device, bool is_fc)
  	if (t == 0)
  		return -ETIMEDOUT;
 
+	if (!status_check)
+		return ret;
+
  	if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO ||
  	    vstor_packet->status != 0)
  		return -EINVAL;
 
+	return ret;
+}
+
+static int storvsc_channel_init(struct hv_device *device, bool is_fc)
+{
+	struct storvsc_device *stor_device;
+	struct storvsc_cmd_request *request;
+	struct vstor_packet *vstor_packet;
+	int ret, i;
+	int max_chns;
+	bool process_sub_channels = false;
+
+	stor_device = get_out_stor_device(device);
+	if (!stor_device)
+		return -ENODEV;
+
+	request = &stor_device->init_request;
+	vstor_packet = &request->vstor_packet;
+
+	/*
+	 * Now, initiate the vsc/vsp initialization protocol on the open
+	 * channel
+	 */
+	memset(request, 0, sizeof(struct storvsc_cmd_request));
+	vstor_packet->operation = VSTOR_OPERATION_BEGIN_INITIALIZATION;
+	ret = storvsc_execute_vstor_op(device, request, true);
+	if (ret)
+		return ret;
+	/*
+	 * Query host supported protocol version.
+	 */
 
  	for (i = 0; i < ARRAY_SIZE(vmstor_protocols); i++) {
  		/* reuse the packet for version range supported */
  		memset(vstor_packet, 0, sizeof(struct vstor_packet));
  		vstor_packet->operation =
  			VSTOR_OPERATION_QUERY_PROTOCOL_VERSION;
-		vstor_packet->flags = REQUEST_COMPLETION_FLAG;
 
  		vstor_packet->version.major_minor =
  			vmstor_protocols[i].protocol_version;

@@ -780,20 +801,10 @@ static int storvsc_channel_init(struct hv_device *device, bool is_fc)
  		 * The revision number is only used in Windows; set it to 0.
  		 */
  		vstor_packet->version.revision = 0;
-
-		ret = vmbus_sendpacket(device->channel, vstor_packet,
-			       (sizeof(struct vstor_packet) -
-				vmscsi_size_delta),
-			       (unsigned long)request,
-			       VM_PKT_DATA_INBAND,
-			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
+		ret = storvsc_execute_vstor_op(device, request, false);
  		if (ret != 0)
  			return ret;
 
-		t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
-		if (t == 0)
-			return -ETIMEDOUT;
-
  		if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO)
  			return -EINVAL;

@@ -817,26 +828,10 @@ static int storvsc_channel_init(struct hv_device *device, bool is_fc)
 
  	memset(vstor_packet, 0, sizeof(struct vstor_packet));
  	vstor_packet->operation = VSTOR_OPERATION_QUERY_PROPERTIES;
-	vstor_packet->flags = REQUEST_COMPLETION_FLAG;
-
-	ret = vmbus_sendpacket(device->channel, vstor_packet,
-			       (sizeof(struct vstor_packet) -
-				vmscsi_size_delta),
-			       (unsigned long)request,
-			       VM_PKT_DATA_INBAND,
-			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
-
+	ret = storvsc_execute_vstor_op(device, request, true);
  	if (ret != 0)
  		return ret;
 
-	t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
-	if (t == 0)
-		return -ETIMEDOUT;
-
-	if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO ||
-	    vstor_packet->status != 0)
-		return -EINVAL;
-
  	/*
  	 * Check to see if multi-channel support is there.
  	 * Hosts that implement protocol version of 5.1 and above

@@ -854,28 +849,15 @@ static int storvsc_channel_init(struct hv_device *device, bool is_fc)
  	if (!is_fc)
  		goto done;
 
+	/*
+	 * For FC devices retrieve FC HBA data.
+	 */
  	memset(vstor_packet, 0, sizeof(struct vstor_packet));
  	vstor_packet->operation = VSTOR_OPERATION_FCHBA_DATA;
-	vstor_packet->flags = REQUEST_COMPLETION_FLAG;
-
-	ret = vmbus_sendpacket(device->channel, vstor_packet,
-			       (sizeof(struct vstor_packet) -
-			       vmscsi_size_delta),
-			       (unsigned long)request,
-			       VM_PKT_DATA_INBAND,
-			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
-
+	ret = storvsc_execute_vstor_op(device, request, true);
  	if (ret != 0)
  		return ret;
 
-	t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
-	if (t == 0)
-		return -ETIMEDOUT;
-
-	if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO ||
-	    vstor_packet->status != 0)
-		return -EINVAL;
-
  	/*
  	 * Cache the currently active port and node ww names.
  	 */

@@ -885,26 +867,10 @@ done:
 
  	memset(vstor_packet, 0, sizeof(struct vstor_packet));
  	vstor_packet->operation = VSTOR_OPERATION_END_INITIALIZATION;
-	vstor_packet->flags = REQUEST_COMPLETION_FLAG;
-
-	ret = vmbus_sendpacket(device->channel, vstor_packet,
-			       (sizeof(struct vstor_packet) -
-				vmscsi_size_delta),
-			       (unsigned long)request,
-			       VM_PKT_DATA_INBAND,
-			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
-
+	ret = storvsc_execute_vstor_op(device, request, true);
  	if (ret != 0)
  		return ret;
 
-	t = wait_for_completion_timeout(&request->wait_event, 5*HZ);

drivers/scsi/storvsc_drv.c done: · line 876

Quoted 10 lines

drivers/scsi/storvsc_drv.c +0 -7

-	if (t == 0)
-		return -ETIMEDOUT;
-
-	if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO ||
-	    vstor_packet->status != 0)
-		return -EINVAL;
-
  	if (process_sub_channels)
  		handle_multichannel_storage(device, max_chns);

The same applies here; please make the FC support configurable both during configuration and during runtime.

Cheers,

Hannes

Signature · 9 lines

Dr. Hannes Reinecke		               zSeries & Storage
[email protected]			               +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG Nürnberg)
--
To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html

K. Y. Srinivasan

author

2015-12-13 18:55 UTC #9 lore raw

PATCH v3 4/4 scsi: storvsc: Tighten up the interrupt path

In reply to K. Y. Srinivasan

On the interrupt path, we repeatedly establish the pointer to the storvsc_device. Fix this.

Signed-off-by K. Y. Srinivasan <[email protected]>

Reviewed-by Long Li <[email protected]>

Reviewed-by Johannes Thumshirn <[email protected]>

Tested-by Alex Ng <[email protected]>

---
 drivers/scsi/storvsc_drv.c |   23 ++++++++---------------
 1 files changed, 8 insertions(+), 15 deletions(-)

drivers/scsi/storvsc_drv.c +8 ~~-15~~

index d6ca4f2..b68aebe 100644
@@ -945,19 +945,16 @@ static void storvsc_handle_error(struct vmscsi_request *vm_srb,
 }
 
 
-static void storvsc_command_completion(struct storvsc_cmd_request *cmd_request)
+static void storvsc_command_completion(struct storvsc_cmd_request *cmd_request,
+				       struct storvsc_device *stor_dev)
 {
 	struct scsi_cmnd *scmnd = cmd_request->cmd;
-	struct hv_host_device *host_dev = shost_priv(scmnd->device->host);
 	struct scsi_sense_hdr sense_hdr;
 	struct vmscsi_request *vm_srb;
 	struct Scsi_Host *host;
-	struct storvsc_device *stor_dev;
-	struct hv_device *dev = host_dev->dev;
 	u32 payload_sz = cmd_request->payload_sz;
 	void *payload = cmd_request->payload;
 
-	stor_dev = get_in_stor_device(dev);
 	host = stor_dev->host;
 
 	vm_srb = &cmd_request->vstor_packet.vm_srb;

@@ -987,14 +984,13 @@ static void storvsc_command_completion(struct storvsc_cmd_request *cmd_request)
 		kfree(payload);
 }
 
-static void storvsc_on_io_completion(struct hv_device *device,
+static void storvsc_on_io_completion(struct storvsc_device *stor_device,
 				  struct vstor_packet *vstor_packet,
 				  struct storvsc_cmd_request *request)
 {
-	struct storvsc_device *stor_device;
 	struct vstor_packet *stor_pkt;
+	struct hv_device *device = stor_device->device;
 
-	stor_device = hv_get_drvdata(device);
 	stor_pkt = &request->vstor_packet;
 
 	/*

@@ -1049,7 +1045,7 @@ static void storvsc_on_io_completion(struct hv_device *device,
 	stor_pkt->vm_srb.data_transfer_length =
 	vstor_packet->vm_srb.data_transfer_length;
 
-	storvsc_command_completion(request);
+	storvsc_command_completion(request, stor_device);
 
 	if (atomic_dec_and_test(&stor_device->num_outstanding_req) &&
 		stor_device->drain_notify)

@@ -1058,21 +1054,19 @@ static void storvsc_on_io_completion(struct hv_device *device,
 
 }
 
-static void storvsc_on_receive(struct hv_device *device,
+static void storvsc_on_receive(struct storvsc_device *stor_device,
 			     struct vstor_packet *vstor_packet,
 			     struct storvsc_cmd_request *request)
 {
 	struct storvsc_scan_work *work;
-	struct storvsc_device *stor_device;
 
 	switch (vstor_packet->operation) {
 	case VSTOR_OPERATION_COMPLETE_IO:
-		storvsc_on_io_completion(device, vstor_packet, request);
+		storvsc_on_io_completion(stor_device, vstor_packet, request);
 		break;
 
 	case VSTOR_OPERATION_REMOVE_DEVICE:
 	case VSTOR_OPERATION_ENUMERATE_BUS:
-		stor_device = get_in_stor_device(device);
 		work = kmalloc(sizeof(struct storvsc_scan_work), GFP_ATOMIC);
 		if (!work)
 			return;

@@ -1083,7 +1077,6 @@ static void storvsc_on_receive(struct hv_device *device,
 		break;
 
 	case VSTOR_OPERATION_FCHBA_DATA:
-		stor_device = get_in_stor_device(device);
 		cache_wwn(stor_device, vstor_packet);
 #ifdef CONFIG_SCSI_FC_ATTRS
 		fc_host_node_name(stor_device->host) = stor_device->node_name;

@@ -1133,7 +1126,7 @@ static void storvsc_on_channel_callback(void *context)
 					vmscsi_size_delta));
 				complete(&request->wait_event);
 			} else {
-				storvsc_on_receive(device,
+				storvsc_on_receive(stor_device,
 						(struct vstor_packet *)packet,
 						request);
 			}

Signature · 1 line

1.7.4.1

Hannes Reinecke

2015-12-18 08:51 UTC #10 lore raw

Re: [PATCH V3 4/4] scsi: storvsc: Tighten up the interrupt path

Quoted 97 lines · K. Y. Srinivasan

On the interrupt path, we repeatedly establish the pointer to the storvsc_device. Fix this.

Signed-off-by K. Y. Srinivasan <[email protected]>

Reviewed-by Long Li <[email protected]>

Reviewed-by Johannes Thumshirn <[email protected]>

Tested-by Alex Ng <[email protected]>

---
  drivers/scsi/storvsc_drv.c |   23 ++++++++---------------
  1 files changed, 8 insertions(+), 15 deletions(-)

drivers/scsi/storvsc_drv.c +7 ~~-14~~

index d6ca4f2..b68aebe 100644
@@ -945,19 +945,16 @@ static void storvsc_handle_error(struct vmscsi_request *vm_srb,
  }
 
 
-static void storvsc_command_completion(struct storvsc_cmd_request *cmd_request)
+static void storvsc_command_completion(struct storvsc_cmd_request *cmd_request,
+				       struct storvsc_device *stor_dev)
  {
  	struct scsi_cmnd *scmnd = cmd_request->cmd;
-	struct hv_host_device *host_dev = shost_priv(scmnd->device->host);
  	struct scsi_sense_hdr sense_hdr;
  	struct vmscsi_request *vm_srb;
  	struct Scsi_Host *host;
-	struct storvsc_device *stor_dev;
-	struct hv_device *dev = host_dev->dev;
  	u32 payload_sz = cmd_request->payload_sz;
  	void *payload = cmd_request->payload;
 
-	stor_dev = get_in_stor_device(dev);
  	host = stor_dev->host;
 
  	vm_srb = &cmd_request->vstor_packet.vm_srb;

@@ -987,14 +984,13 @@ static void storvsc_command_completion(struct storvsc_cmd_request *cmd_request)
  		kfree(payload);
  }
 
-static void storvsc_on_io_completion(struct hv_device *device,
+static void storvsc_on_io_completion(struct storvsc_device *stor_device,
  				  struct vstor_packet *vstor_packet,
  				  struct storvsc_cmd_request *request)
  {
-	struct storvsc_device *stor_device;
  	struct vstor_packet *stor_pkt;
+	struct hv_device *device = stor_device->device;
 
-	stor_device = hv_get_drvdata(device);
  	stor_pkt = &request->vstor_packet;
 
  	/*

@@ -1049,7 +1045,7 @@ static void storvsc_on_io_completion(struct hv_device *device,
  	stor_pkt->vm_srb.data_transfer_length =
  	vstor_packet->vm_srb.data_transfer_length;
 
-	storvsc_command_completion(request);
+	storvsc_command_completion(request, stor_device);
 
  	if (atomic_dec_and_test(&stor_device->num_outstanding_req) &&
  		stor_device->drain_notify)

@@ -1058,21 +1054,19 @@ static void storvsc_on_io_completion(struct hv_device *device,
 
  }
 
-static void storvsc_on_receive(struct hv_device *device,
+static void storvsc_on_receive(struct storvsc_device *stor_device,
  			     struct vstor_packet *vstor_packet,
  			     struct storvsc_cmd_request *request)
  {
  	struct storvsc_scan_work *work;
-	struct storvsc_device *stor_device;
 
  	switch (vstor_packet->operation) {
  	case VSTOR_OPERATION_COMPLETE_IO:
-		storvsc_on_io_completion(device, vstor_packet, request);
+		storvsc_on_io_completion(stor_device, vstor_packet, request);
  		break;
 
  	case VSTOR_OPERATION_REMOVE_DEVICE:
  	case VSTOR_OPERATION_ENUMERATE_BUS:
-		stor_device = get_in_stor_device(device);
  		work = kmalloc(sizeof(struct storvsc_scan_work), GFP_ATOMIC);
  		if (!work)
  			return;

@@ -1083,7 +1077,6 @@ static void storvsc_on_receive(struct hv_device *device,
  		break;
 
  	case VSTOR_OPERATION_FCHBA_DATA:
-		stor_device = get_in_stor_device(device);
  		cache_wwn(stor_device, vstor_packet);
  #ifdef CONFIG_SCSI_FC_ATTRS
  		fc_host_node_name(stor_device->host) = stor_device->node_name;

drivers/scsi/storvsc_drv.c static void storvsc_on_channel_callback(void *context) · line 1132

Quoted 8 lines

drivers/scsi/storvsc_drv.c +1 -1

@@ -1133,7 +1126,7 @@ static void storvsc_on_channel_callback(void *context)
  					vmscsi_size_delta));
  				complete(&request->wait_event);
  			} else {
-				storvsc_on_receive(device,
+				storvsc_on_receive(stor_device,
  						(struct vstor_packet *)packet,
  						request);
  			}

Hmm. I would've thought the compiler optimizes this away. Have you checked whether it actually makes a difference in the assembler output?

Cheers,

Hannes

Signature · 5 lines

Dr. Hannes Reinecke		               zSeries & Storage
[email protected]			               +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG Nürnberg)

KY Srinivasan

author

2015-12-18 16:20 UTC #11 lore raw

RE: [PATCH V3 4/4] scsi: storvsc: Tighten up the interrupt path

Quoted 128 lines

-----Original Message-----
From: Hannes Reinecke [mailto:[email protected]]
Sent: Friday, December 18, 2015 12:52 AM
To: KY Srinivasan <[email protected]>; [email protected]; linux- [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]
Subject: Re: [PATCH V3 4/4] scsi: storvsc: Tighten up the interrupt path
drivers/scsi/storvsc_drv.c static void storvsc_handle_error(struct
Quoted 16 lines · K. Y. Srinivasan
On the interrupt path, we repeatedly establish the pointer to the storvsc_device. Fix this.
Signed-off-by K. Y. Srinivasan <[email protected]>
Reviewed-by Long Li <[email protected]>
Reviewed-by Johannes Thumshirn <[email protected]>
Tested-by Alex Ng <[email protected]>
---
  drivers/scsi/storvsc_drv.c |   23 ++++++++---------------
  1 files changed, 8 insertions(+), 15 deletions(-)
drivers/scsi/storvsc_drv.c +0 -0
index d6ca4f2..b68aebe 100644
@@ -945,19 +945,16 @@ static void storvsc_handle_error(struct
vmscsi_request *vm_srb,
drivers/scsi/storvsc_drv.c static void storvsc_handle_error(struct · line 948
Quoted 4 lines
drivers/scsi/storvsc_drv.c +0 -1
  }
 
 
-static void storvsc_command_completion(struct storvsc_cmd_request
*cmd_request)
drivers/scsi/storvsc_drv.c static void storvsc_handle_error(struct · line 948
Quoted 1 line
drivers/scsi/storvsc_drv.c +1 -0
+static void storvsc_command_completion(struct storvsc_cmd_request
*cmd_request,
drivers/scsi/storvsc_drv.c static void storvsc_command_completion(struct
Quoted 18 lines
drivers/scsi/storvsc_drv.c +1 -4
+				       struct storvsc_device *stor_dev)
  {
  	struct scsi_cmnd *scmnd = cmd_request->cmd;
-	struct hv_host_device *host_dev = shost_priv(scmnd->device-
 host);
  	struct scsi_sense_hdr sense_hdr;
  	struct vmscsi_request *vm_srb;
  	struct Scsi_Host *host;
-	struct storvsc_device *stor_dev;
-	struct hv_device *dev = host_dev->dev;
  	u32 payload_sz = cmd_request->payload_sz;
  	void *payload = cmd_request->payload;
 
-	stor_dev = get_in_stor_device(dev);
  	host = stor_dev->host;
 
  	vm_srb = &cmd_request->vstor_packet.vm_srb;
drivers/scsi/storvsc_drv.c +0 -0
@@ -987,14 +984,13 @@ static void storvsc_command_completion(struct
storvsc_cmd_request *cmd_request)
drivers/scsi/storvsc_drv.c static void storvsc_on_io_completion(struct
Quoted 17 lines
drivers/scsi/storvsc_drv.c +2 -3
  		kfree(payload);
  }
 
-static void storvsc_on_io_completion(struct hv_device *device,
+static void storvsc_on_io_completion(struct storvsc_device *stor_device,
  				  struct vstor_packet *vstor_packet,
  				  struct storvsc_cmd_request *request)
  {
-	struct storvsc_device *stor_device;
  	struct vstor_packet *stor_pkt;
+	struct hv_device *device = stor_device->device;
 
-	stor_device = hv_get_drvdata(device);
  	stor_pkt = &request->vstor_packet;
 
  	/*
@@ -1049,7 +1045,7 @@ static void storvsc_on_io_completion(struct
hv_device *device,
drivers/scsi/storvsc_drv.c static void storvsc_on_io_completion(struct
Quoted 9 lines
drivers/scsi/storvsc_drv.c +1 -1
  	stor_pkt->vm_srb.data_transfer_length =
  	vstor_packet->vm_srb.data_transfer_length;
 
-	storvsc_command_completion(request);
+	storvsc_command_completion(request, stor_device);
 
  	if (atomic_dec_and_test(&stor_device->num_outstanding_req) &&
  		stor_device->drain_notify)
@@ -1058,21 +1054,19 @@ static void storvsc_on_io_completion(struct
hv_device *device,
Quoted 5 lines
drivers/scsi/storvsc_drv.c +1 -1
  }
 
-static void storvsc_on_receive(struct hv_device *device,
+static void storvsc_on_receive(struct storvsc_device *stor_device,
drivers/scsi/storvsc_drv.c static void storvsc_on_io_completion(struct hv_device *device,
Quoted 10 lines
drivers/scsi/storvsc_drv.c +1 -2
  			     struct vstor_packet *vstor_packet,
  			     struct storvsc_cmd_request *request)
  {
  	struct storvsc_scan_work *work;
-	struct storvsc_device *stor_device;
 
  	switch (vstor_packet->operation) {
  	case VSTOR_OPERATION_COMPLETE_IO:
-		storvsc_on_io_completion(device, vstor_packet, request);
+		storvsc_on_io_completion(stor_device, vstor_packet,
request);
drivers/scsi/storvsc_drv.c static void storvsc_on_io_completion(struct hv_device *device,
Quoted 6 lines
drivers/scsi/storvsc_drv.c +0 -1
  		break;
 
  	case VSTOR_OPERATION_REMOVE_DEVICE:
  	case VSTOR_OPERATION_ENUMERATE_BUS:
-		stor_device = get_in_stor_device(device);
  		work = kmalloc(sizeof(struct storvsc_scan_work),
GFP_ATOMIC);
drivers/scsi/storvsc_drv.c static void storvsc_on_receive(struct hv_device
Quoted 3 lines
drivers/scsi/storvsc_drv.c +0 -0
  		if (!work)
  			return;
@@ -1083,7 +1077,6 @@ static void storvsc_on_receive(struct hv_device
*device,
drivers/scsi/storvsc_drv.c static void storvsc_on_channel_callback(void
Quoted 9 lines
drivers/scsi/storvsc_drv.c +0 -1
  		break;
 
  	case VSTOR_OPERATION_FCHBA_DATA:
-		stor_device = get_in_stor_device(device);
  		cache_wwn(stor_device, vstor_packet);
  #ifdef CONFIG_SCSI_FC_ATTRS
  		fc_host_node_name(stor_device->host) = stor_device-
node_name;
drivers/scsi/storvsc_drv.c +0 -0
@@ -1133,7 +1126,7 @@ static void storvsc_on_channel_callback(void
*context)
drivers/scsi/storvsc_drv.c static void storvsc_on_channel_callback(void *context)
Quoted 6 lines
drivers/scsi/storvsc_drv.c +1 -1
  					vmscsi_size_delta));
  				complete(&request->wait_event);
  			} else {
-				storvsc_on_receive(device,
+				storvsc_on_receive(stor_device,
  						(struct vstor_packet
*)packet,

Quoted 5 lines

drivers/scsi/storvsc_drv.c static void storvsc_on_channel_callback(void *context) · line 1132
Quoted 3 lines
drivers/scsi/storvsc_drv.c +0 -0
  						request);
  			}
Hmm. I would've thought the compiler optimizes this away. Have you checked whether it actually makes a difference in the assembler output?

I have not checked the assembler output. It was easy enough to fix the source.

K. Y

Quoted 10 lines

Cheers,
Hannes
--
Dr. Hannes Reinecke zSeries & Storage
[email protected] +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton HRB 21284 (AG Nürnberg)

James Bottomley

maintainer

2015-12-18 16:48 UTC #12 lore raw

Re: [PATCH V3 4/4] scsi: storvsc: Tighten up the interrupt path

Quoted 154 lines · KY Srinivasan

Quoted 154 lines
-----Original Message-----
From: Hannes Reinecke [mailto:[email protected]]
Sent: Friday, December 18, 2015 12:52 AM
To: KY Srinivasan <[email protected]>; [email protected]; linux-
[email protected]; [email protected]; [email protected];
[email protected]; [email protected]; [email protected];
[email protected]; [email protected]; [email protected]; [email protected]
Subject: Re: [PATCH V3 4/4] scsi: storvsc: Tighten up the interrupt path
drivers/scsi/storvsc_drv.c static void storvsc_handle_error(struct
Quoted 17 lines · K. Y. Srinivasan
On the interrupt path, we repeatedly establish the pointer to the storvsc_device. Fix this.
Signed-off-by K. Y. Srinivasan <[email protected]>
Reviewed-by Long Li <[email protected]>
Reviewed-by Johannes Thumshirn <[email protected]>
Tested-by Alex Ng <[email protected]>
---
  drivers/scsi/storvsc_drv.c |   23 ++++++++---------------
  1 files changed, 8 insertions(+), 15 deletions(-)
drivers/scsi/storvsc_drv.c +0 -0
index d6ca4f2..b68aebe 100644
@@ -945,19 +945,16 @@ static void storvsc_handle_error(struct
vmscsi_request *vm_srb,
Quoted 5 lines
drivers/scsi/storvsc_drv.c +0 -1
  }
 
 
-static void storvsc_command_completion(struct
storvsc_cmd_request
*cmd_request)
Quoted 2 lines
+static void storvsc_command_completion(struct storvsc_cmd_request
*cmd_request,
Quoted 20 lines
drivers/scsi/storvsc_drv.c +1 -0
+				       struct storvsc_device
*stor_dev)
{
struct scsi_cmnd *scmnd = cmd_request->cmd;
drivers/scsi/storvsc_drv.c +0 -2
-	struct hv_host_device *host_dev = shost_priv(scmnd
->device-
host);
struct scsi_sense_hdr sense_hdr; struct vmscsi_request *vm_srb; struct Scsi_Host *host;
drivers/scsi/storvsc_drv.c +0 -3
-	struct storvsc_device *stor_dev;
-	struct hv_device *dev = host_dev->dev;
  	u32 payload_sz = cmd_request->payload_sz;
  	void *payload = cmd_request->payload;
 
-	stor_dev = get_in_stor_device(dev);
  	host = stor_dev->host;
 
  	vm_srb = &cmd_request->vstor_packet.vm_srb;
@@ -987,14 +984,13 @@ static void
Quoted 1 line
storvsc_command_completion(struct
storvsc_cmd_request *cmd_request)
drivers/scsi/storvsc_drv.c static void storvsc_on_io_completion(struct
Quoted 20 lines
  		kfree(payload);
  }
drivers/scsi/storvsc_drv.c +1 -1
-static void storvsc_on_io_completion(struct hv_device *device,
+static void storvsc_on_io_completion(struct storvsc_device
*stor_device,
struct vstor_packet
*vstor_packet,
struct storvsc_cmd_request
*request)
{
drivers/scsi/storvsc_drv.c +1 -2
-	struct storvsc_device *stor_device;
  	struct vstor_packet *stor_pkt;
+	struct hv_device *device = stor_device->device;
 
-	stor_device = hv_get_drvdata(device);
  	stor_pkt = &request->vstor_packet;
 
  	/*
@@ -1049,7 +1045,7 @@ static void storvsc_on_io_completion(struct
hv_device *device,
Quoted 11 lines
drivers/scsi/storvsc_drv.c +1 -2
  	stor_pkt->vm_srb.data_transfer_length =
  	vstor_packet->vm_srb.data_transfer_length;
 
-	storvsc_command_completion(request);
+	storvsc_command_completion(request, stor_device);
 
  	if (atomic_dec_and_test(&stor_device
->num_outstanding_req) &&
  		stor_device->drain_notify)
@@ -1058,21 +1054,19 @@ static void
storvsc_on_io_completion(struct
hv_device *device,
Quoted 18 lines
  }
drivers/scsi/storvsc_drv.c +1 -1
-static void storvsc_on_receive(struct hv_device *device,
+static void storvsc_on_receive(struct storvsc_device
*stor_device,
struct vstor_packet *vstor_packet, struct storvsc_cmd_request
*request)
{
struct storvsc_scan_work *work;
drivers/scsi/storvsc_drv.c +0 -2
-	struct storvsc_device *stor_device;
 
  	switch (vstor_packet->operation) {
  	case VSTOR_OPERATION_COMPLETE_IO:
-		storvsc_on_io_completion(device, vstor_packet,
request);
drivers/scsi/storvsc_drv.c +1 -0
+		storvsc_on_io_completion(stor_device,
Quoted 1 line
vstor_packet,
request);
Quoted 7 lines
break;
case VSTOR_OPERATION_REMOVE_DEVICE:
case VSTOR_OPERATION_ENUMERATE_BUS:
drivers/scsi/storvsc_drv.c +0 -1
-		stor_device = get_in_stor_device(device);
  		work = kmalloc(sizeof(struct
storvsc_scan_work),
GFP_ATOMIC);
Quoted 4 lines
if (!work)
return;
drivers/scsi/storvsc_drv.c +0 -0
@@ -1083,7 +1077,6 @@ static void storvsc_on_receive(struct
hv_device
*device,
Quoted 11 lines
break;
case VSTOR_OPERATION_FCHBA_DATA:
drivers/scsi/storvsc_drv.c +0 -1
-		stor_device = get_in_stor_device(device);
  		cache_wwn(stor_device, vstor_packet);
  #ifdef CONFIG_SCSI_FC_ATTRS
  		fc_host_node_name(stor_device->host) =
stor_device-
node_name;
drivers/scsi/storvsc_drv.c +0 -0
@@ -1133,7 +1126,7 @@ static void
storvsc_on_channel_callback(void
*context)
Quoted 7 lines
  					vmscsi_size_delta));
  				complete(&request->wait_event);
  			} else {
drivers/scsi/storvsc_drv.c +1 -1
-				storvsc_on_receive(device,
+				storvsc_on_receive(stor_device,
  						(struct
vstor_packet
*)packet,
Quoted 3 lines
  						request);
  			}

Quoted 6 lines

Quoted 3 lines
Hmm. I would've thought the compiler optimizes this away. Have you checked whether it actually makes a difference in the assembler output?
I have not checked the assembler output. It was easy enough to fix the source.

Could you? You're making what you describe as an optimisation but there are two reasons why this might not be so. The first is that the compiler is entitled to inline static functions. If it did, likely it picked up the optmisation anyway as Hannes suggested. However, the other reason this might not be an optimisation (assuming the compiler doesn't inline the function) is you're passing an argument which can be offset computed. On all architectures, you have a fixed number of registers for passing function arguments, then we have to use the stack. Using the stack comes in far more expensive than computing an offset to an existing pointer. Even if you're still in registers, the offset now has to be computed and stored and the compiler loses track of the relation.

The bottom line is that adding an extra argument for a value which can be offset computed is rarely a win.

James

KY Srinivasan

author

2015-12-19 02:28 UTC #13 lore raw

RE: [PATCH V3 4/4] scsi: storvsc: Tighten up the interrupt path

Quoted 188 lines

-----Original Message-----
From: James Bottomley [mailto:[email protected]]
Sent: Friday, December 18, 2015 8:48 AM
To: KY Srinivasan <[email protected]>; Hannes Reinecke <[email protected]>; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]
Subject: Re: [PATCH V3 4/4] scsi: storvsc: Tighten up the interrupt path
Quoted 154 lines · KY Srinivasan
Quoted 154 lines
-----Original Message-----
From: Hannes Reinecke [mailto:[email protected]]
Sent: Friday, December 18, 2015 12:52 AM
To: KY Srinivasan <[email protected]>; [email protected]; linux-
[email protected]; [email protected]; [email protected];
[email protected]; [email protected]; [email protected];
[email protected]; [email protected]; [email protected]; [email protected]
Subject: Re: [PATCH V3 4/4] scsi: storvsc: Tighten up the interrupt path
drivers/scsi/storvsc_drv.c static void storvsc_handle_error(struct
Quoted 17 lines · K. Y. Srinivasan
On the interrupt path, we repeatedly establish the pointer to the storvsc_device. Fix this.
Signed-off-by K. Y. Srinivasan <[email protected]>
Reviewed-by Long Li <[email protected]>
Reviewed-by Johannes Thumshirn <[email protected]>
Tested-by Alex Ng <[email protected]>
---
  drivers/scsi/storvsc_drv.c |   23 ++++++++---------------
  1 files changed, 8 insertions(+), 15 deletions(-)
drivers/scsi/storvsc_drv.c +0 -0
index d6ca4f2..b68aebe 100644
@@ -945,19 +945,16 @@ static void storvsc_handle_error(struct
vmscsi_request *vm_srb,
Quoted 5 lines
drivers/scsi/storvsc_drv.c +0 -1
  }
 
 
-static void storvsc_command_completion(struct
storvsc_cmd_request
*cmd_request)
Quoted 2 lines
+static void storvsc_command_completion(struct storvsc_cmd_request
*cmd_request,
Quoted 20 lines
drivers/scsi/storvsc_drv.c +1 -0
+				       struct storvsc_device
*stor_dev)
{
struct scsi_cmnd *scmnd = cmd_request->cmd;
drivers/scsi/storvsc_drv.c +0 -2
-	struct hv_host_device *host_dev = shost_priv(scmnd
->device-
host);
struct scsi_sense_hdr sense_hdr; struct vmscsi_request *vm_srb; struct Scsi_Host *host;
drivers/scsi/storvsc_drv.c +0 -3
-	struct storvsc_device *stor_dev;
-	struct hv_device *dev = host_dev->dev;
  	u32 payload_sz = cmd_request->payload_sz;
  	void *payload = cmd_request->payload;
 
-	stor_dev = get_in_stor_device(dev);
  	host = stor_dev->host;
 
  	vm_srb = &cmd_request->vstor_packet.vm_srb;
@@ -987,14 +984,13 @@ static void
Quoted 1 line
storvsc_command_completion(struct
storvsc_cmd_request *cmd_request)
drivers/scsi/storvsc_drv.c static void storvsc_on_io_completion(struct
Quoted 20 lines
  		kfree(payload);
  }
drivers/scsi/storvsc_drv.c +1 -1
-static void storvsc_on_io_completion(struct hv_device *device,
+static void storvsc_on_io_completion(struct storvsc_device
*stor_device,
struct vstor_packet
*vstor_packet,
struct storvsc_cmd_request
*request)
{
drivers/scsi/storvsc_drv.c +1 -2
-	struct storvsc_device *stor_device;
  	struct vstor_packet *stor_pkt;
+	struct hv_device *device = stor_device->device;
 
-	stor_device = hv_get_drvdata(device);
  	stor_pkt = &request->vstor_packet;
 
  	/*
@@ -1049,7 +1045,7 @@ static void storvsc_on_io_completion(struct
hv_device *device,
Quoted 11 lines
drivers/scsi/storvsc_drv.c +1 -2
  	stor_pkt->vm_srb.data_transfer_length =
  	vstor_packet->vm_srb.data_transfer_length;
 
-	storvsc_command_completion(request);
+	storvsc_command_completion(request, stor_device);
 
  	if (atomic_dec_and_test(&stor_device
->num_outstanding_req) &&
  		stor_device->drain_notify)
@@ -1058,21 +1054,19 @@ static void
storvsc_on_io_completion(struct
hv_device *device,
Quoted 18 lines
  }
drivers/scsi/storvsc_drv.c +1 -1
-static void storvsc_on_receive(struct hv_device *device,
+static void storvsc_on_receive(struct storvsc_device
*stor_device,
struct vstor_packet *vstor_packet, struct storvsc_cmd_request
*request)
{
struct storvsc_scan_work *work;
drivers/scsi/storvsc_drv.c +0 -2
-	struct storvsc_device *stor_device;
 
  	switch (vstor_packet->operation) {
  	case VSTOR_OPERATION_COMPLETE_IO:
-		storvsc_on_io_completion(device, vstor_packet,
request);
drivers/scsi/storvsc_drv.c +1 -0
+		storvsc_on_io_completion(stor_device,
Quoted 1 line
vstor_packet,
request);
Quoted 7 lines
break;
case VSTOR_OPERATION_REMOVE_DEVICE:
case VSTOR_OPERATION_ENUMERATE_BUS:
drivers/scsi/storvsc_drv.c +0 -1
-		stor_device = get_in_stor_device(device);
  		work = kmalloc(sizeof(struct
storvsc_scan_work),
GFP_ATOMIC);
Quoted 4 lines
if (!work)
return;
drivers/scsi/storvsc_drv.c +0 -0
@@ -1083,7 +1077,6 @@ static void storvsc_on_receive(struct
hv_device
*device,
Quoted 11 lines
break;
case VSTOR_OPERATION_FCHBA_DATA:
drivers/scsi/storvsc_drv.c +0 -1
-		stor_device = get_in_stor_device(device);
  		cache_wwn(stor_device, vstor_packet);
  #ifdef CONFIG_SCSI_FC_ATTRS
  		fc_host_node_name(stor_device->host) =
stor_device-
node_name;
drivers/scsi/storvsc_drv.c +0 -0
@@ -1133,7 +1126,7 @@ static void
storvsc_on_channel_callback(void
*context)
Quoted 7 lines
  					vmscsi_size_delta));
  				complete(&request->wait_event);
  			} else {
drivers/scsi/storvsc_drv.c +1 -1
-				storvsc_on_receive(device,
+				storvsc_on_receive(stor_device,
  						(struct
vstor_packet
*)packet,
Quoted 3 lines
  						request);
  			}
Quoted 6 lines
Quoted 3 lines
Hmm. I would've thought the compiler optimizes this away. Have you checked whether it actually makes a difference in the assembler output?
I have not checked the assembler output. It was easy enough to fix the source.
Could you? You're making what you describe as an optimisation but there are two reasons why this might not be so. The first is that the compiler is entitled to inline static functions. If it did, likely it picked up the optmisation anyway as Hannes suggested. However, the other reason this might not be an optimisation (assuming the compiler doesn't inline the function) is you're passing an argument which can be offset computed. On all architectures, you have a fixed number of registers for passing function arguments, then we have to use the stack. Using the stack comes in far more expensive than computing an offset to an existing pointer. Even if you're still in registers, the offset now has to be computed and stored and the compiler loses track of the relation.

Quoted 2 lines

The bottom line is that adding an extra argument for a value which can be offset computed is rarely a win.

James,
When I did this, I was mostly concerned about the cost of reestablishing state that was already known. So, even with the function being in-lined, I felt the cost of reestablishing state that was already known is unnecessary. In this particular case, I did not change the number of arguments that were being passed; I just changed the type of one of them - instead of passing struct hv_device *, I am now passing struct storvsc_device *. In the current code, we are using struct hv_device * to establish a pointer to struct storvsc_device * via the function get_in_stor_device(). This pattern currently exists in the call chain from the interrupt handler - storvsc_on_channel_callback().

While the compiler is smart enough to inline both get_in_stor_device() as well as many of the static functions in the call chain from storvsc_on_channel_callback(), looking at the assembled code, the compiler is repeatedly inlining the call to get_in_stor_device() and this clearly is less than optimal.

Regards,

K. Y

Hannes Reinecke

Reviewed-by

2015-12-21 07:42 UTC #14 lore raw

Re: [PATCH V3 4/4] scsi: storvsc: Tighten up the interrupt path

Quoted 1 line · KY Srinivasan

[ .. ]

Quoted 27 lines

Quoted 14 lines
Could you? You're making what you describe as an optimisation but there are two reasons why this might not be so. The first is that the compiler is entitled to inline static functions. If it did, likely it picked up the optmisation anyway as Hannes suggested. However, the other reason this might not be an optimisation (assuming the compiler doesn't inline the function) is you're passing an argument which can be offset computed. On all architectures, you have a fixed number of registers for passing function arguments, then we have to use the stack. Using the stack comes in far more expensive than computing an offset to an existing pointer. Even if you're still in registers, the offset now has to be computed and stored and the compiler loses track of the relation.
Quoted 2 lines
The bottom line is that adding an extra argument for a value which can be offset computed is rarely a win.
James,
When I did this, I was mostly concerned about the cost of reestablishing state that was already known. So, even with the function being in-lined, I felt the cost of reestablishing state that was already known is unnecessary. In this particular case, I did not change the number of arguments that were being passed; I just changed the type of one of them - instead of passing struct hv_device *, I am now passing struct storvsc_device *. In the current code, we are using struct hv_device * to establish a pointer to struct storvsc_device * via the function get_in_stor_device(). This pattern currently exists in the call chain from the interrupt handler - storvsc_on_channel_callback().

Quoted 4 lines

While the compiler is smart enough to inline both get_in_stor_device() as well as many of the static functions in the call chain from storvsc_on_channel_callback(), looking at the assembled code, the compiler is repeatedly inlining the call to get_in_stor_device() and this clearly is less than optimal.

Which means you actually checked the compiler output, and it made a difference.

That's all I wanted to know, as it's not immediately clear from the patch.

So:

Reviewed-by Hannes Reinecke <[email protected]>

Cheers,

Hannes

Signature · 9 lines

Dr. Hannes Reinecke		               zSeries & Storage
[email protected]			               +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG Nürnberg)
_______________________________________________
devel mailing list
[email protected]
http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel

James Bottomley

maintainer

2015-12-21 16:28 UTC #15 lore raw

Re: [PATCH V3 4/4] scsi: storvsc: Tighten up the interrupt path

In reply to KY Srinivasan

Quoted 232 lines · KY Srinivasan

Quoted 211 lines
-----Original Message-----
From: James Bottomley [mailto:[email protected] ]
Sent: Friday, December 18, 2015 8:48 AM
To: KY Srinivasan <[email protected]>; Hannes Reinecke < [email protected]>;
[email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected];
[email protected]; [email protected]; [email protected]; [email protected]
Subject: Re: [PATCH V3 4/4] scsi: storvsc: Tighten up the interrupt path
Quoted 165 lines · KY Srinivasan
Quoted 165 lines
-----Original Message-----
From: Hannes Reinecke [mailto:[email protected]]
Sent: Friday, December 18, 2015 12:52 AM
To: KY Srinivasan <[email protected]>; [email protected];
linux-
[email protected]; [email protected]; [email protected];
[email protected]; [email protected]; [email protected];
[email protected]; [email protected]; [email protected]; [email protected]
Subject: Re: [PATCH V3 4/4] scsi: storvsc: Tighten up the interrupt
path
drivers/scsi/storvsc_drv.c static void storvsc_handle_error(struct
Quoted 18 lines · K. Y. Srinivasan
On the interrupt path, we repeatedly establish the pointer to the
storvsc_device. Fix this.
Signed-off-by K. Y. Srinivasan <[email protected]>
Reviewed-by Long Li <[email protected]>
Reviewed-by Johannes Thumshirn <[email protected]>
Tested-by Alex Ng <[email protected]>
---
  drivers/scsi/storvsc_drv.c |   23 ++++++++---------------
  1 files changed, 8 insertions(+), 15 deletions(-)
drivers/scsi/storvsc_drv.c +0 -0
index d6ca4f2..b68aebe 100644
@@ -945,19 +945,16 @@ static void storvsc_handle_error(struct
vmscsi_request *vm_srb,
Quoted 5 lines
drivers/scsi/storvsc_drv.c +0 -1
  }
 
 
-static void storvsc_command_completion(struct
storvsc_cmd_request
*cmd_request)
Quoted 2 lines
+static void storvsc_command_completion(struct storvsc_cmd_request
*cmd_request,
Quoted 20 lines
drivers/scsi/storvsc_drv.c +1 -0
+				       struct storvsc_device
*stor_dev)
{
struct scsi_cmnd *scmnd = cmd_request->cmd;
drivers/scsi/storvsc_drv.c +0 -2
-	struct hv_host_device *host_dev = shost_priv(scmnd
->device-
host);
struct scsi_sense_hdr sense_hdr; struct vmscsi_request *vm_srb; struct Scsi_Host *host;
drivers/scsi/storvsc_drv.c +0 -3
-	struct storvsc_device *stor_dev;
-	struct hv_device *dev = host_dev->dev;
  	u32 payload_sz = cmd_request->payload_sz;
  	void *payload = cmd_request->payload;
 
-	stor_dev = get_in_stor_device(dev);
  	host = stor_dev->host;
 
  	vm_srb = &cmd_request->vstor_packet.vm_srb;
@@ -987,14 +984,13 @@ static void
Quoted 1 line
storvsc_command_completion(struct
storvsc_cmd_request *cmd_request)
Quoted 22 lines
  		kfree(payload);
  }
-static void storvsc_on_io_completion(struct hv_device *device,
+static void storvsc_on_io_completion(struct storvsc_device *stor_device,
struct vstor_packet
*vstor_packet,
struct
storvsc_cmd_request
*request)
{
drivers/scsi/storvsc_drv.c +1 -2
-	struct storvsc_device *stor_device;
  	struct vstor_packet *stor_pkt;
+	struct hv_device *device = stor_device->device;
 
-	stor_device = hv_get_drvdata(device);
  	stor_pkt = &request->vstor_packet;
 
  	/*
@@ -1049,7 +1045,7 @@ static void
Quoted 1 line
storvsc_on_io_completion(struct
hv_device *device,
Quoted 11 lines
stor_pkt->vm_srb.data_transfer_length = vstor_packet->vm_srb.data_transfer_length;
drivers/scsi/storvsc_drv.c +1 -2
-	storvsc_command_completion(request);
+	storvsc_command_completion(request, stor_device);
 
  	if (atomic_dec_and_test(&stor_device
->num_outstanding_req) &&
  		stor_device->drain_notify)
@@ -1058,21 +1054,19 @@ static void
storvsc_on_io_completion(struct
hv_device *device,
Quoted 20 lines
  }
drivers/scsi/storvsc_drv.c +1 -1
-static void storvsc_on_receive(struct hv_device *device,
+static void storvsc_on_receive(struct storvsc_device
*stor_device,
struct vstor_packet
*vstor_packet,
struct storvsc_cmd_request
*request)
{
struct storvsc_scan_work *work;
drivers/scsi/storvsc_drv.c +0 -2
-	struct storvsc_device *stor_device;
 
  	switch (vstor_packet->operation) {
  	case VSTOR_OPERATION_COMPLETE_IO:
-		storvsc_on_io_completion(device,
vstor_packet,
request);
drivers/scsi/storvsc_drv.c +1 -0
+		storvsc_on_io_completion(stor_device,
Quoted 1 line
vstor_packet,
request);
Quoted 7 lines
break;
case VSTOR_OPERATION_REMOVE_DEVICE:
case VSTOR_OPERATION_ENUMERATE_BUS:
drivers/scsi/storvsc_drv.c +0 -1
-		stor_device = get_in_stor_device(device);
  		work = kmalloc(sizeof(struct
storvsc_scan_work),
GFP_ATOMIC);
Quoted 4 lines
if (!work)
return;
drivers/scsi/storvsc_drv.c +0 -0
@@ -1083,7 +1077,6 @@ static void storvsc_on_receive(struct
hv_device
*device,
Quoted 11 lines
break;
case VSTOR_OPERATION_FCHBA_DATA:
drivers/scsi/storvsc_drv.c +0 -1
-		stor_device = get_in_stor_device(device);
  		cache_wwn(stor_device, vstor_packet);
  #ifdef CONFIG_SCSI_FC_ATTRS
  		fc_host_node_name(stor_device->host) =
stor_device-
node_name;
drivers/scsi/storvsc_drv.c +0 -0
@@ -1133,7 +1126,7 @@ static void
storvsc_on_channel_callback(void
*context)
Quoted 10 lines
vmscsi_size_delta))
;
complete(&request
->wait_event);
} else {
drivers/scsi/storvsc_drv.c +1 -1
-				storvsc_on_receive(device,
+				storvsc_on_receive(stor_devi
ce,
(struct
vstor_packet
*)packet,
Quoted 3 lines
  						request);
  			}
Quoted 8 lines
Quoted 4 lines
Hmm. I would've thought the compiler optimizes this away. Have you
checked whether it actually makes a difference in the assembler output?
I have not checked the assembler output. It was easy enough to fix
the source.
Could you? You're making what you describe as an optimisation but there are two reasons why this might not be so. The first is that the
compiler is entitled to inline static functions. If it did, likely it
picked up the optmisation anyway as Hannes suggested. However, the other reason this might not be an optimisation (assuming the compiler
doesn't inline the function) is you're passing an argument which can be
offset computed. On all architectures, you have a fixed number of registers for passing function arguments, then we have to use the stack. Using the stack comes in far more expensive than computing an
offset to an existing pointer. Even if you're still in registers, the
offset now has to be computed and stored and the compiler loses track
of the relation.
Quoted 3 lines
The bottom line is that adding an extra argument for a value which can
be offset computed is rarely a win.
James,
When I did this, I was mostly concerned about the cost of reestablishing state that was
already known. So, even with the function being in-lined, I felt the cost of reestablishing
state that was already known is unnecessary. In this particular case, I did not change the
number of arguments that were being passed; I just changed the type of one of them -
instead of passing struct hv_device *, I am now passing struct storvsc_device *. In the
current code, we are using struct hv_device * to establish a pointer to struct storvsc_device *
via the function get_in_stor_device(). This pattern currently exists in the call chain from the
interrupt handler - storvsc_on_channel_callback().

Quoted 6 lines

While the compiler is smart enough to inline both get_in_stor_device() as well as many of the static functions in the call chain from storvsc_on_channel_callback(), looking at the assembled code,
the compiler is repeatedly inlining the call to get_in_stor_device() and this clearly is less than optimal.

OK, so the reason for the recomputation is the destruction condition check which is evaluated every time you call it? Perhaps what you simply want is an __get_in_stor_device() that does the offset mathematics without the destruction check. It's doing exactly what passing the additional parameter does: the calling function is taking on the burden of verifying they've got a device which is still valid.

I'm not making this a hard requirement for reviewing the code: you have arguments to spare in the functions, so I don't think it matters which way this is done. I do, however, think it makes consumers of the stor device think about why they're using it and whether they actually need the destruct check.

James

KY Srinivasan

author

2015-12-21 19:40 UTC #16 lore raw

RE: [PATCH V3 4/4] scsi: storvsc: Tighten up the interrupt path

Quoted 261 lines

-----Original Message-----
From: James Bottomley [mailto:[email protected]]
Sent: Monday, December 21, 2015 8:28 AM
To: KY Srinivasan <[email protected]>; Hannes Reinecke <[email protected]>; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]
Subject: Re: [PATCH V3 4/4] scsi: storvsc: Tighten up the interrupt path
Quoted 3 lines · KY Srinivasan
Quoted 3 lines
-----Original Message-----
From: James Bottomley
[mailto:[email protected]
Quoted 229 lines
Quoted 208 lines
]
Sent: Friday, December 18, 2015 8:48 AM
To: KY Srinivasan <[email protected]>; Hannes Reinecke < [email protected]>;
[email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected];
[email protected]; [email protected]; [email protected]; [email protected]
Subject: Re: [PATCH V3 4/4] scsi: storvsc: Tighten up the interrupt path
Quoted 165 lines · KY Srinivasan
Quoted 165 lines
-----Original Message-----
From: Hannes Reinecke [mailto:[email protected]]
Sent: Friday, December 18, 2015 12:52 AM
To: KY Srinivasan <[email protected]>; [email protected];
linux-
[email protected]; [email protected]; [email protected];
[email protected]; [email protected]; [email protected];
[email protected]; [email protected]; [email protected]; [email protected]
Subject: Re: [PATCH V3 4/4] scsi: storvsc: Tighten up the interrupt
path
drivers/scsi/storvsc_drv.c static void storvsc_handle_error(struct
Quoted 18 lines · K. Y. Srinivasan
On the interrupt path, we repeatedly establish the pointer to the
storvsc_device. Fix this.
Signed-off-by K. Y. Srinivasan <[email protected]>
Reviewed-by Long Li <[email protected]>
Reviewed-by Johannes Thumshirn <[email protected]>
Tested-by Alex Ng <[email protected]>
---
  drivers/scsi/storvsc_drv.c |   23 ++++++++---------------
  1 files changed, 8 insertions(+), 15 deletions(-)
drivers/scsi/storvsc_drv.c +0 -0
index d6ca4f2..b68aebe 100644
@@ -945,19 +945,16 @@ static void storvsc_handle_error(struct
vmscsi_request *vm_srb,
Quoted 5 lines
drivers/scsi/storvsc_drv.c +0 -1
  }
 
 
-static void storvsc_command_completion(struct
storvsc_cmd_request
*cmd_request)
Quoted 2 lines
+static void storvsc_command_completion(struct storvsc_cmd_request
*cmd_request,
Quoted 20 lines
drivers/scsi/storvsc_drv.c +1 -0
+				       struct storvsc_device
*stor_dev)
{
struct scsi_cmnd *scmnd = cmd_request->cmd;
drivers/scsi/storvsc_drv.c +0 -2
-	struct hv_host_device *host_dev = shost_priv(scmnd
->device-
host);
struct scsi_sense_hdr sense_hdr; struct vmscsi_request *vm_srb; struct Scsi_Host *host;
drivers/scsi/storvsc_drv.c +0 -3
-	struct storvsc_device *stor_dev;
-	struct hv_device *dev = host_dev->dev;
  	u32 payload_sz = cmd_request->payload_sz;
  	void *payload = cmd_request->payload;
 
-	stor_dev = get_in_stor_device(dev);
  	host = stor_dev->host;
 
  	vm_srb = &cmd_request->vstor_packet.vm_srb;
@@ -987,14 +984,13 @@ static void
Quoted 1 line
storvsc_command_completion(struct
storvsc_cmd_request *cmd_request)
Quoted 22 lines
  		kfree(payload);
  }
-static void storvsc_on_io_completion(struct hv_device *device,
+static void storvsc_on_io_completion(struct storvsc_device *stor_device,
struct vstor_packet
*vstor_packet,
struct
storvsc_cmd_request
*request)
{
drivers/scsi/storvsc_drv.c +1 -2
-	struct storvsc_device *stor_device;
  	struct vstor_packet *stor_pkt;
+	struct hv_device *device = stor_device->device;
 
-	stor_device = hv_get_drvdata(device);
  	stor_pkt = &request->vstor_packet;
 
  	/*
@@ -1049,7 +1045,7 @@ static void
Quoted 1 line
storvsc_on_io_completion(struct
hv_device *device,
Quoted 11 lines
stor_pkt->vm_srb.data_transfer_length = vstor_packet->vm_srb.data_transfer_length;
drivers/scsi/storvsc_drv.c +1 -2
-	storvsc_command_completion(request);
+	storvsc_command_completion(request, stor_device);
 
  	if (atomic_dec_and_test(&stor_device
->num_outstanding_req) &&
  		stor_device->drain_notify)
@@ -1058,21 +1054,19 @@ static void
storvsc_on_io_completion(struct
hv_device *device,
Quoted 20 lines
  }
drivers/scsi/storvsc_drv.c +1 -1
-static void storvsc_on_receive(struct hv_device *device,
+static void storvsc_on_receive(struct storvsc_device
*stor_device,
struct vstor_packet
*vstor_packet,
struct storvsc_cmd_request
*request)
{
struct storvsc_scan_work *work;
drivers/scsi/storvsc_drv.c +0 -2
-	struct storvsc_device *stor_device;
 
  	switch (vstor_packet->operation) {
  	case VSTOR_OPERATION_COMPLETE_IO:
-		storvsc_on_io_completion(device,
vstor_packet,
request);
drivers/scsi/storvsc_drv.c +1 -0
+		storvsc_on_io_completion(stor_device,
Quoted 1 line
vstor_packet,
request);
Quoted 7 lines
break;
case VSTOR_OPERATION_REMOVE_DEVICE:
case VSTOR_OPERATION_ENUMERATE_BUS:
drivers/scsi/storvsc_drv.c +0 -1
-		stor_device = get_in_stor_device(device);
  		work = kmalloc(sizeof(struct
storvsc_scan_work),
GFP_ATOMIC);
Quoted 4 lines
if (!work)
return;
drivers/scsi/storvsc_drv.c +0 -0
@@ -1083,7 +1077,6 @@ static void storvsc_on_receive(struct
hv_device
*device,
Quoted 11 lines
break;
case VSTOR_OPERATION_FCHBA_DATA:
drivers/scsi/storvsc_drv.c +0 -1
-		stor_device = get_in_stor_device(device);
  		cache_wwn(stor_device, vstor_packet);
  #ifdef CONFIG_SCSI_FC_ATTRS
  		fc_host_node_name(stor_device->host) =
stor_device-
node_name;
drivers/scsi/storvsc_drv.c +0 -0
@@ -1133,7 +1126,7 @@ static void
storvsc_on_channel_callback(void
*context)
Quoted 10 lines
vmscsi_size_delta))
;
complete(&request
->wait_event);
} else {
drivers/scsi/storvsc_drv.c +1 -1
-				storvsc_on_receive(device,
+				storvsc_on_receive(stor_devi
ce,
(struct
vstor_packet
*)packet,
Quoted 3 lines
  						request);
  			}
Quoted 8 lines
Quoted 4 lines
Hmm. I would've thought the compiler optimizes this away. Have you
checked whether it actually makes a difference in the assembler output?
I have not checked the assembler output. It was easy enough to fix
the source.
Could you? You're making what you describe as an optimisation but there are two reasons why this might not be so. The first is that the
compiler is entitled to inline static functions. If it did, likely it
picked up the optmisation anyway as Hannes suggested. However, the other reason this might not be an optimisation (assuming the compiler
doesn't inline the function) is you're passing an argument which can be
offset computed. On all architectures, you have a fixed number of registers for passing function arguments, then we have to use the stack. Using the stack comes in far more expensive than computing an
offset to an existing pointer. Even if you're still in registers, the
offset now has to be computed and stored and the compiler loses track
of the relation.
Quoted 3 lines
The bottom line is that adding an extra argument for a value which can
be offset computed is rarely a win.
James,
When I did this, I was mostly concerned about the cost of reestablishing state that was
already known. So, even with the function being in-lined, I felt the cost of reestablishing
state that was already known is unnecessary. In this particular case, I did not change the
number of arguments that were being passed; I just changed the type of one of them -
instead of passing struct hv_device *, I am now passing struct storvsc_device *. In the
current code, we are using struct hv_device * to establish a pointer to struct storvsc_device *
via the function get_in_stor_device(). This pattern currently exists in the call chain from the
interrupt handler - storvsc_on_channel_callback().
Quoted 6 lines
While the compiler is smart enough to inline both get_in_stor_device() as well as many of the static functions in the call chain from storvsc_on_channel_callback(), looking at the assembled code,
the compiler is repeatedly inlining the call to get_in_stor_device() and this clearly is less than optimal.
OK, so the reason for the recomputation is the destruction condition check which is evaluated every time you call it? Perhaps what you simply want is an __get_in_stor_device() that does the offset mathematics without the destruction check. It's doing exactly what passing the additional parameter does: the calling function is taking on the burden of verifying they've got a device which is still valid.

Quoted 3 lines

I'm not making this a hard requirement for reviewing the code: you have arguments to spare in the functions, so I don't think it matters which way this is done.

Agreed.

Quoted 3 lines

I do, however, think it makes consumers of the stor
device think about why they're using it and whether they actually need the destruct check.

There is higher level serialization that makes the destruct check unnecessary once we get past the check in the first function in the interrupt handler for this driver - storvsc_on_channel_callback().
In the absence of this, the destruct check is meaningless since the state can change soon after it has been checked. So, if it is ok with you, I will add additional comment to the commit log and resubmit the patch.

Regards,

K. Y

Hannes Reinecke

Reviewed-by on v3 1/4

2015-12-18 08:40 UTC #17 lore raw

Re: [PATCH V3 1/4] scsi: storvsc: Fix a bug in the layout of the hv_fc_wwn_packet

In reply to K. Y. Srinivasan

Quoted 18 lines · K. Y. Srinivasan

The hv_fc_wwn_packet is exchanged over vmbus. Make the definition in Linux match the Window's definition.
Signed-off-by K. Y. Srinivasan <[email protected]>
Reviewed-by Johannes Thumshirn <[email protected]>
Reviewed-by Long Li <[email protected]>
Tested-by Alex Ng <[email protected]>
---
  drivers/scsi/storvsc_drv.c |    5 ++---
  1 files changed, 2 insertions(+), 3 deletions(-)
drivers/scsi/storvsc_drv.c +0 -0
index c41f674..00bb4bd 100644
@@ -92,9 +92,8 @@ enum vstor_packet_operation {
   */

drivers/scsi/storvsc_drv.c enum vstor_packet_operation { · line 99

Quoted 10 lines

drivers/scsi/storvsc_drv.c +2 -3

 
  struct hv_fc_wwn_packet {
-	bool	primary_active;
-	u8	reserved1;
-	u8	reserved2;
+	u8	primary_active;
+	u8	reserved1[3];
  	u8	primary_port_wwn[8];
  	u8	primary_node_wwn[8];
  	u8	secondary_port_wwn[8];

Reviewed-by Hannes Reinecke <[email protected]>

Cheers,

Hannes

Signature · 5 lines

Dr. Hannes Reinecke		               zSeries & Storage
[email protected]			               +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG Nürnberg)