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Update scsi host to use ida for host number

PATCH Superseded [email protected] 2 participants 3 messages Sep 1, 2015 SCSI

v2 of 3 Superseded Latest is v3 →

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#0 lore raw

PATCH v2 1/1 Update scsi host to use ida for host number

From: Lee Duncan <[email protected]>

Each Scsi_host instance gets a host number starting at 0, but this is implemented with an atomic integer, and rollover doesn't seem to have been considered. Another side-effect of this design is that scsi host numbers used by iscsi are never reused, thereby making rollover more likely. This patch converts Scsi_host instances to use ida to manage their instance numbers.

This also means that host instance numbers will be reused, when available.

Changes from v1:
* Added inline host_put_index() and its use

Signed-off-by Lee Duncan <[email protected]>
Reviewed-by Hannes Reinecke <[email protected]>
Reviewed-by Johannes Thumshirn <[email protected]>
---
 drivers/scsi/hosts.c | 47 +++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 39 insertions(+), 8 deletions(-)
drivers/scsi/hosts.c +39 -8
index 8bb173e01084..36cb65612821 100644
@@ -33,7 +33,7 @@
 #include <linux/transport_class.h>
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
-
+#include <linux/idr.h>
 #include <scsi/scsi_device.h>
 #include <scsi/scsi_host.h>
 #include <scsi/scsi_transport.h>

@@ -42,7 +42,8 @@
 #include "scsi_logging.h"
 
 
-static atomic_t scsi_host_next_hn = ATOMIC_INIT(0);	/* host_no for next new host */
+static DEFINE_SPINLOCK(host_index_lock);
+static DEFINE_IDA(host_index_ida);
 
 
 static void scsi_host_cls_release(struct device *dev)

@@ -337,6 +338,10 @@ static void scsi_host_dev_release(struct device *dev)
 
 	kfree(shost->shost_data);
 
+	spin_lock(&host_index_lock);
+	ida_remove(&host_index_ida, shost->host_no);
+	spin_unlock(&host_index_lock);
+
 	if (parent)
 		put_device(parent);
 	kfree(shost);

@@ -353,6 +358,28 @@ static struct device_type scsi_host_type = {
 	.release =	scsi_host_dev_release,
 };
 
+static int host_get_index(int *index)
+{
+	int error = -ENOMEM;
+
+	do {
+		if (!ida_pre_get(&host_index_ida, GFP_KERNEL))
+			break;
+		spin_lock(&host_index_lock);
+		error = ida_get_new(&host_index_ida, index);
+		spin_unlock(&host_index_lock);
+	} while (error == -EAGAIN);
+
+	return error;
+}
+
+static inline void host_put_index(int index)
+{
+	spin_lock(&host_index_lock);
+	ida_remove(&host_index_ida, index);
+	spin_unlock(&host_index_lock);
+}
+
 /**
  * scsi_host_alloc - register a scsi host adapter instance.
  * @sht:	pointer to scsi host template

@@ -370,6 +397,8 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
 {
 	struct Scsi_Host *shost;
 	gfp_t gfp_mask = GFP_KERNEL;
+	int index;
+	int error;
 
 	if (sht->unchecked_isa_dma && privsize)
 		gfp_mask |= __GFP_DMA;

@@ -388,11 +417,11 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
 	init_waitqueue_head(&shost->host_wait);
 	mutex_init(&shost->scan_mutex);
 
-	/*
-	 * subtract one because we increment first then return, but we need to
-	 * know what the next host number was before increment
-	 */
-	shost->host_no = atomic_inc_return(&scsi_host_next_hn) - 1;
+	error = host_get_index(&index);
+	if (error < 0)
+		goto fail_kfree;
+	shost->host_no = index;
+
 	shost->dma_channel = 0xff;
 
 	/* These three are default values which can be overridden */

@@ -477,7 +506,7 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
 		shost_printk(KERN_WARNING, shost,
 			"error handler thread failed to spawn, error = %ld\n",
 			PTR_ERR(shost->ehandler));
-		goto fail_kfree;
+		goto fail_free_index;
 	}
 
 	shost->tmf_work_q = alloc_workqueue("scsi_tmf_%d",

@@ -493,6 +522,8 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
 
  fail_kthread:
 	kthread_stop(shost->ehandler);
+ fail_free_index:
+	host_put_index(index);
  fail_kfree:
 	kfree(shost);
 	return NULL;
Signature · 1 line
2.1.4
#1 lore raw
Quoted 48 lines · On 9/1/2015 8:38 PM, [email protected] wrote:

From: Lee Duncan <[email protected]>

Each Scsi_host instance gets a host number starting at 0, but this is implemented with an atomic integer, and rollover doesn't seem to have been considered. Another side-effect of this design is that scsi host numbers used by iscsi are never reused, thereby making rollover more likely. This patch converts Scsi_host instances to use ida to manage their instance numbers.

This also means that host instance numbers will be reused, when available.

Changes from v1:
* Added inline host_put_index() and its use

Signed-off-by Lee Duncan <[email protected]>
Reviewed-by Hannes Reinecke <[email protected]>
Reviewed-by Johannes Thumshirn <[email protected]>
---
  drivers/scsi/hosts.c | 47 +++++++++++++++++++++++++++++++++++++++--------
  1 file changed, 39 insertions(+), 8 deletions(-)
drivers/scsi/hosts.c +3 -2
index 8bb173e01084..36cb65612821 100644
@@ -33,7 +33,7 @@
  #include <linux/transport_class.h>
  #include <linux/platform_device.h>
  #include <linux/pm_runtime.h>
-
+#include <linux/idr.h>
  #include <scsi/scsi_device.h>
  #include <scsi/scsi_host.h>
  #include <scsi/scsi_transport.h>

@@ -42,7 +42,8 @@
  #include "scsi_logging.h"
 
 
-static atomic_t scsi_host_next_hn = ATOMIC_INIT(0);	/* host_no for next new host */
+static DEFINE_SPINLOCK(host_index_lock);
+static DEFINE_IDA(host_index_ida);
 
 
  static void scsi_host_cls_release(struct device *dev)

drivers/scsi/hosts.c static void scsi_host_dev_release(struct device *dev) · line 343

Quoted 6 lines
drivers/scsi/hosts.c +3 -0
@@ -337,6 +338,10 @@ static void scsi_host_dev_release(struct device *dev)
 
  	kfree(shost->shost_data);
 
+	spin_lock(&host_index_lock);
+	ida_remove(&host_index_ida, shost->host_no);
+	spin_unlock(&host_index_lock);

Why not host_put_index(index)?

author
#2 lore raw
Quoted 53 lines · Sagi Grimberg
Quoted 52 lines · On 9/1/2015 8:38 PM, [email protected] wrote:

From: Lee Duncan <[email protected]>

Each Scsi_host instance gets a host number starting at 0, but this is implemented with an atomic integer, and rollover doesn't seem to have been considered. Another side-effect of this design is that scsi host numbers used by iscsi are never reused, thereby making rollover more likely. This patch converts Scsi_host instances to use ida to manage their instance numbers.

This also means that host instance numbers will be reused, when available.

Changes from v1:
* Added inline host_put_index() and its use

Signed-off-by Lee Duncan <[email protected]>
Reviewed-by Hannes Reinecke <[email protected]>
Reviewed-by Johannes Thumshirn <[email protected]>
---
  drivers/scsi/hosts.c | 47
+++++++++++++++++++++++++++++++++++++++--------
  1 file changed, 39 insertions(+), 8 deletions(-)
drivers/scsi/hosts.c +1 -2
index 8bb173e01084..36cb65612821 100644
@@ -33,7 +33,7 @@
  #include <linux/transport_class.h>
  #include <linux/platform_device.h>
  #include <linux/pm_runtime.h>
-
+#include <linux/idr.h>
  #include <scsi/scsi_device.h>
  #include <scsi/scsi_host.h>
  #include <scsi/scsi_transport.h>

@@ -42,7 +42,8 @@
  #include "scsi_logging.h"
 
 
-static atomic_t scsi_host_next_hn = ATOMIC_INIT(0);    /* host_no for

next new host */

drivers/scsi/hosts.c +2 -0
+static DEFINE_SPINLOCK(host_index_lock);
+static DEFINE_IDA(host_index_ida);
 
 
  static void scsi_host_cls_release(struct device *dev)

@@ -337,6 +338,10 @@ static void scsi_host_dev_release(struct device
 *dev)
Quoted 8 lines

drivers/scsi/hosts.c static void scsi_host_dev_release(struct device *dev) · line 343

Quoted 5 lines
drivers/scsi/hosts.c +3 -0
      kfree(shost->shost_data);
 
+    spin_lock(&host_index_lock);
+    ida_remove(&host_index_ida, shost->host_no);
+    spin_unlock(&host_index_lock);

Why not host_put_index(index)?

Doh! I'll fix that in both places.

Signature · 1 line
Lee Duncan