scsi_debug lk 2.6.0t6

PATCH In review Douglas Gilbert 2 participants 3 messages Oct 7, 2003 – Oct 9, 2003 SCSI

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Douglas Gilbert

author

2003-10-07 11:01 UTC #0 lore raw

PATCH 1/1 scsi_debug lk 2.6.0t6

This small patch adds a "release" method to the "pseudo_0" device to stop the noise when the scsi_debug module is loaded.

Another annoyance that I was unable to get to the bottom of was during "rmmod scsi_debug" **:
Synchronizing SCSI cache for disk sda: <4>FAILED

    status = 0, message = 00, host = 1, driver = 00

That is a DID_NO_CONNECT error. So the LLD host is being shut down before the sd driver gets a chance to send through a SYNCHRONIZE CACHE command. If the user instigates a rmmod (as distinct from the hardware saying the host/device is gone), shouldn't a window be left open for such a flushing type command. This problem seems to have appeared recently.

** "echo -1 > add_host" in scsi_debug's driver directory
(i.e. remove a host) also causes the same error so the problem is not perculiar to rmmod.

Doug Gilbert

drivers/scsi/scsi_debug.c260t6dpg renamed from drivers/scsi/scsi_debug.c +9 -2

@@ -55,7 +55,7 @@
 #include "scsi_logging.h"
 #include "scsi_debug.h"
 
-static const char * scsi_debug_version_str = "Version: 1.70 (20030507)";
+static const char * scsi_debug_version_str = "Version: 1.71 (20031007)";
 
 /* Additional Sense Code (ASC) used */
 #define NO_ADDED_SENSE 0x0

@@ -1541,7 +1541,7 @@
         }
 
 	if (SCSI_DEBUG_OPT_NOISE & scsi_debug_opts) {
-		printk(KERN_INFO "scsi_debug: ... built %d host(s)\n",
+		printk(KERN_INFO "scsi_debug_init: built %d host(s)\n",
 		       scsi_debug_add_host);
 	}
 	return 0;

@@ -1565,8 +1565,15 @@
 device_initcall(scsi_debug_init);
 module_exit(scsi_debug_exit);
 
+void pseudo_0_release(struct device * dev)
+{
+	if (SCSI_DEBUG_OPT_NOISE & scsi_debug_opts)
+		printk(KERN_INFO "scsi_debug: pseudo_0_release() called\n");
+}
+
 static struct device pseudo_primary = {
 	.bus_id		= "pseudo_0",
+	.release	= pseudo_0_release,
 };
 
 static int pseudo_lld_bus_match(struct device *dev,

Douglas Gilbert

author

2003-10-08 12:58 UTC #1 lore raw

After playing around with:

# echo "0 - -" > /sys/class/scsi_host/host1/scan

(where host1 is owned by the scsi_debug driver), I have made some more changes to the driver
(now version 1.72). These changes permit the number of scsi devices that the driver simulates to be increased via sysfs without necessarily adding new hosts. [add_host can still be used to add or remove hosts.]

Here is an example:

# modprobe scsi_debug    # assume adds host 1
# echo 3 > /sys/bus/pseudo/drivers/scsi_debug/max_luns
# echo 2 > /sys/bus/pseudo/drivers/scsi_debug/max_tgts
# echo "0 - -" > /sys/class/scsi_host/host1/scan

The modprobe line adds one scsi device and the echo "0 - -" line adds 5 more scsi devices to host 1.

Retired the documentation in this page:
http://www.torque.net/sg/sdebug25.html
and replaced it with this reworked page:
http://www.torque.net/sg/sdebug26.html

Doug Gilbert

Quoted 17 lines · Douglas Gilbert

This small patch adds a "release" method to the "pseudo_0" device to stop the noise when the scsi_debug module is loaded.
Another annoyance that I was unable to get to the bottom of was during "rmmod scsi_debug" **:
Synchronizing SCSI cache for disk sda: <4>FAILED
    status = 0, message = 00, host = 1, driver = 00
That is a DID_NO_CONNECT error. So the LLD host is being shut down before the sd driver gets a chance to send through a SYNCHRONIZE CACHE command. If the user instigates a rmmod (as distinct from the hardware saying the host/device is gone), shouldn't a window be left open for such a flushing type command. This problem seems to have appeared recently.

Quoted 5 lines

** "echo -1 > add_host" in scsi_debug's driver directory
(i.e. remove a host) also causes the same error so the problem is not perculiar to rmmod.
Doug Gilbert

New patch ...

drivers/scsi/scsi_debug.c260t6dpg2 renamed from drivers/scsi/scsi_debug.c +43 -2

@@ -55,7 +55,7 @@
 #include "scsi_logging.h"
 #include "scsi_debug.h"
 
-static const char * scsi_debug_version_str = "Version: 1.70 (20030507)";
+static const char * scsi_debug_version_str = "Version: 1.72 (20031008)";
 
 /* Additional Sense Code (ASC) used */
 #define NO_ADDED_SENSE 0x0

@@ -249,6 +249,8 @@
 
 static int sdebug_add_adapter(void);
 static void sdebug_remove_adapter(void);
+static void sdebug_max_tgts_luns(void);
+
 static struct device pseudo_primary;
 static struct bus_type pseudo_lld_bus;

@@ -981,6 +983,18 @@
 				open_devip = devip;
 		}
 	}
+	if (NULL == open_devip) { /* try and make a new one */
+		open_devip = kmalloc(sizeof(*open_devip),GFP_KERNEL);
+                if (NULL == open_devip) {
+                        printk(KERN_ERR "%s: out of memory at line %d\n",
+                               __FUNCTION__, __LINE__);
+                        return NULL;
+                }
+                memset(open_devip, 0, sizeof(*open_devip));
+                open_devip->sdbg_host = sdbg_host;
+                list_add_tail(&open_devip->dev_list,
+                              &sdbg_host->dev_info_list);
+	}
         if (open_devip) {
 		open_devip->channel = sdev->channel;
 		open_devip->target = sdev->id;

@@ -1369,6 +1383,7 @@
 
 	if ((count > 0) && (1 == sscanf(buf, "%d", &n)) && (n >= 0)) {
 		scsi_debug_num_tgts = n;
+		sdebug_max_tgts_luns();
 		return count;
 	}
 	return -EINVAL;

@@ -1412,6 +1427,7 @@
 
 	if ((count > 0) && (1 == sscanf(buf, "%d", &n)) && (n >= 0)) {
 		scsi_debug_max_luns = n;
+		sdebug_max_tgts_luns();
 		return count;
 	}
 	return -EINVAL;

@@ -1541,7 +1557,7 @@
         }
 
 	if (SCSI_DEBUG_OPT_NOISE & scsi_debug_opts) {
-		printk(KERN_INFO "scsi_debug: ... built %d host(s)\n",
+		printk(KERN_INFO "scsi_debug_init: built %d host(s)\n",
 		       scsi_debug_add_host);
 	}
 	return 0;

@@ -1565,8 +1581,15 @@
 device_initcall(scsi_debug_init);
 module_exit(scsi_debug_exit);
 
+void pseudo_0_release(struct device * dev)
+{
+	if (SCSI_DEBUG_OPT_NOISE & scsi_debug_opts)
+		printk(KERN_INFO "scsi_debug: pseudo_0_release() called\n");
+}
+
 static struct device pseudo_primary = {
 	.bus_id		= "pseudo_0",
+	.release	= pseudo_0_release,
 };
 
 static int pseudo_lld_bus_match(struct device *dev,

@@ -1731,3 +1754,21 @@
         scsi_host_put(sdbg_host->shost);
         return 0;
 }
+
+static void sdebug_max_tgts_luns(void)
+{
+	struct sdebug_host_info * sdbg_host;
+        struct Scsi_Host *hpnt;
+
+        spin_lock(&sdebug_host_list_lock);
+        list_for_each_entry(sdbg_host, &sdebug_host_list, host_list) {
+		hpnt = sdbg_host->shost;
+		if ((hpnt->this_id >= 0) && 
+		    (scsi_debug_num_tgts > hpnt->this_id))
+			hpnt->max_id = scsi_debug_num_tgts + 1;
+		else
+			hpnt->max_id = scsi_debug_num_tgts;
+		hpnt->max_lun = scsi_debug_max_luns;
+        }
+        spin_unlock(&sdebug_host_list_lock);
+}

Mike Anderson

2003-10-09 00:31 UTC #2 lore raw

In reply to Douglas Gilbert

Quoted 11 lines · Douglas Gilbert [[email protected]] wrote:

Another annoyance that I was unable to get to the bottom of was during "rmmod scsi_debug" **:
Synchronizing SCSI cache for disk sda: <4>FAILED
    status = 0, message = 00, host = 1, driver = 00
That is a DID_NO_CONNECT error. So the LLD host is being shut down before the sd driver gets a chance to send through a SYNCHRONIZE CACHE command. If the user instigates a rmmod (as distinct from the hardware saying the host/device is gone), shouldn't a window be left open for such a flushing type command. This problem seems to have appeared recently.

It is related to the state added to scsi_remove_host a while ago to stop IO flow.

To allow a window as you indicate we would need some method to determine rmmod vs. unexpected disconnect.

1.) One method would be to add a argument to to scsi_remove_host to allow passing the type of remove from the LLDD.

2.) Another method would be to call a new function to shutdown the children of the host prior to module removal (also setting a flag to stop furthur IO). Then if there was any driver specific actions needed prior to scsi_remove_host the LLDD could have the freedom to do what every it needed.

The sd_shutdown function is already registered as a shutdown function. The only reason it is not called twice is the we never alter the detach_state of the sd struct device. I am unclear what impact the power changes have on these interfaces.

-andmike
--
Michael Anderson
[email protected]