This is a note to let you know that I've just added the patch titled
dm delay: fix a possible deadlock due to shared workqueue
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
dm-delay-fix-a-possible-deadlock-due-to-shared-workqueue.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 718822c1c112dc99e0c72c8968ee1db9d9d910f0 Mon Sep 17 00:00:00 2001
From: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Date: Fri, 15 Nov 2013 16:12:20 -0500
Subject: dm delay: fix a possible deadlock due to shared workqueue
From: Mikulas Patocka <mpatocka@xxxxxxxxxx>
commit 718822c1c112dc99e0c72c8968ee1db9d9d910f0 upstream.
The dm-delay target uses a shared workqueue for multiple instances. This
can cause deadlock if two or more dm-delay targets are stacked on the top
of each other.
This patch changes dm-delay to use a per-instance workqueue.
Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/md/dm-delay.c | 23 +++++++++++------------
1 file changed, 11 insertions(+), 12 deletions(-)
--- a/drivers/md/dm-delay.c
+++ b/drivers/md/dm-delay.c
@@ -20,6 +20,7 @@
struct delay_c {
struct timer_list delay_timer;
struct mutex timer_lock;
+ struct workqueue_struct *kdelayd_wq;
struct work_struct flush_expired_bios;
struct list_head delayed_bios;
atomic_t may_delay;
@@ -45,14 +46,13 @@ struct dm_delay_info {
static DEFINE_MUTEX(delayed_bios_lock);
-static struct workqueue_struct *kdelayd_wq;
static struct kmem_cache *delayed_cache;
static void handle_delayed_timer(unsigned long data)
{
struct delay_c *dc = (struct delay_c *)data;
- queue_work(kdelayd_wq, &dc->flush_expired_bios);
+ queue_work(dc->kdelayd_wq, &dc->flush_expired_bios);
}
static void queue_timeout(struct delay_c *dc, unsigned long expires)
@@ -191,6 +191,12 @@ out:
goto bad_dev_write;
}
+ dc->kdelayd_wq = alloc_workqueue("kdelayd", WQ_MEM_RECLAIM, 0);
+ if (!dc->kdelayd_wq) {
+ DMERR("Couldn't start kdelayd");
+ goto bad_queue;
+ }
+
setup_timer(&dc->delay_timer, handle_delayed_timer, (unsigned long)dc);
INIT_WORK(&dc->flush_expired_bios, flush_expired_bios);
@@ -203,6 +209,8 @@ out:
ti->private = dc;
return 0;
+bad_queue:
+ mempool_destroy(dc->delayed_pool);
bad_dev_write:
if (dc->dev_write)
dm_put_device(ti, dc->dev_write);
@@ -217,7 +225,7 @@ static void delay_dtr(struct dm_target *
{
struct delay_c *dc = ti->private;
- flush_workqueue(kdelayd_wq);
+ destroy_workqueue(dc->kdelayd_wq);
dm_put_device(ti, dc->dev_read);
@@ -351,12 +359,6 @@ static int __init dm_delay_init(void)
{
int r = -ENOMEM;
- kdelayd_wq = alloc_workqueue("kdelayd", WQ_MEM_RECLAIM, 0);
- if (!kdelayd_wq) {
- DMERR("Couldn't start kdelayd");
- goto bad_queue;
- }
-
delayed_cache = KMEM_CACHE(dm_delay_info, 0);
if (!delayed_cache) {
DMERR("Couldn't create delayed bio cache.");
@@ -374,8 +376,6 @@ static int __init dm_delay_init(void)
bad_register:
kmem_cache_destroy(delayed_cache);
bad_memcache:
- destroy_workqueue(kdelayd_wq);
-bad_queue:
return r;
}
@@ -383,7 +383,6 @@ static void __exit dm_delay_exit(void)
{
dm_unregister_target(&delay_target);
kmem_cache_destroy(delayed_cache);
- destroy_workqueue(kdelayd_wq);
}
/* Module hooks */
Patches currently in stable-queue which might be from mpatocka@xxxxxxxxxx are
queue-3.4/dm-table-fail-dm_table_create-on-dm_round_up-overflow.patch
queue-3.4/dm-bufio-initialize-read-only-module-parameters.patch
queue-3.4/dm-delay-fix-a-possible-deadlock-due-to-shared-workqueue.patch
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