[PATCH] Sleeping with spinlock held

[PATCH] Sleeping with spinlock held

[Glauber de Oliveira Costa]

[-- Attachment #1: Type: text/plain, Size: 403 bytes --]

Hi,

In drivers/xen/blkfront/blkfront.c, flush_scheduled_work(), that might
sleep, is being called with a spinlock held, thus triggering a BUG.
I think it's safe to just poke it out from the locked region, as it
seems to me we won't be receiving any more work at this time.

In case you agree, I'm attaching a simple patch that fix this.

-- 
Glauber de Oliveira Costa
Red Hat Inc.
"Free as in Freedom"

[-- Attachment #2: flush_work.patch --]
[-- Type: text/plain, Size: 855 bytes --]

--- linux-2.6.18-orig/drivers/xen/blkfront//blkfront.c.orig	2006-10-07 10:28:25.000000000 -0400
+++ linux-2.6.18-orig/drivers/xen/blkfront//blkfront.c	2006-10-07 10:27:58.000000000 -0400
@@ -355,8 +355,8 @@ static void blkfront_closing(struct xenb
 	blk_stop_queue(info->rq);
 	/* No more gnttab callback work. */
 	gnttab_cancel_free_callback(&info->callback);
-	flush_scheduled_work();
 	spin_unlock_irqrestore(&blkif_io_lock, flags);
+	flush_scheduled_work();
 
 	xlvbd_del(info);
 
@@ -714,8 +714,8 @@ static void blkif_free(struct blkfront_i
 		blk_stop_queue(info->rq);
 	/* No more gnttab callback work. */
 	gnttab_cancel_free_callback(&info->callback);
-	flush_scheduled_work();
 	spin_unlock_irq(&blkif_io_lock);
+	flush_scheduled_work();
 
 	/* Free resources associated with old device channel. */
 	if (info->ring_ref != GRANT_INVALID_REF) {

[-- Attachment #3: Type: text/plain, Size: 138 bytes --]

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[PATCH] Sleeping with spinlock held

[Glauber de Oliveira Costa]

[-- Attachment #1: Type: text/plain, Size: 403 bytes --]

Hi,

In drivers/xen/blkfront/blkfront.c, flush_scheduled_work(), that might
sleep, is being called with a spinlock held, thus triggering a BUG.
I think it's safe to just poke it out from the locked region, as it
seems to me we won't be receiving any more work at this time.

In case you agree, I'm attaching a simple patch that fix this.

-- 
Glauber de Oliveira Costa
Red Hat Inc.
"Free as in Freedom"

[-- Attachment #2: flush_work.patch --]
[-- Type: text/plain, Size: 855 bytes --]

--- linux-2.6.18-orig/drivers/xen/blkfront//blkfront.c.orig	2006-10-07 10:28:25.000000000 -0400
+++ linux-2.6.18-orig/drivers/xen/blkfront//blkfront.c	2006-10-07 10:27:58.000000000 -0400
@@ -355,8 +355,8 @@ static void blkfront_closing(struct xenb
 	blk_stop_queue(info->rq);
 	/* No more gnttab callback work. */
 	gnttab_cancel_free_callback(&info->callback);
-	flush_scheduled_work();
 	spin_unlock_irqrestore(&blkif_io_lock, flags);
+	flush_scheduled_work();
 
 	xlvbd_del(info);
 
@@ -714,8 +714,8 @@ static void blkif_free(struct blkfront_i
 		blk_stop_queue(info->rq);
 	/* No more gnttab callback work. */
 	gnttab_cancel_free_callback(&info->callback);
-	flush_scheduled_work();
 	spin_unlock_irq(&blkif_io_lock);
+	flush_scheduled_work();
 
 	/* Free resources associated with old device channel. */
 	if (info->ring_ref != GRANT_INVALID_REF) {

[-- Attachment #3: Type: text/plain, Size: 138 bytes --]

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Re: [PATCH] Sleeping with spinlock held

[Keir Fraser]

On 9/10/06 8:30 pm, "Glauber de Oliveira Costa" <gcosta@redhat.com> wrote:

> In drivers/xen/blkfront/blkfront.c, flush_scheduled_work(), that might
> sleep, is being called with a spinlock held, thus triggering a BUG.
> I think it's safe to just poke it out from the locked region, as it
> seems to me we won't be receiving any more work at this time.
> 
> In case you agree, I'm attaching a simple patch that fix this.

Already fixed in xen-unstable, but thanks!

 -- Keir