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dm thin: irqsave must always be used with the pool->lock spinlock 

Commit c140e1c4e2 ("dm thin: use per thin device deferred bio lists")
incorrectly stopped disabling irqs when taking the pool's spinlock.

Irqs must be disabled when taking the pool's spinlock otherwise a thread
could spin_lock(), then get interrupted to service thin_endio() in
interrupt context, which would then deadlock in spin_lock_irqsave().

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Joe Thornber 2014-04-08 11:08:41 +01:00 committed by Mike Snitzer
parent 0596661f0a
commit 5e3283e292
1 changed files with 3 additions and 2 deletions
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5
drivers/md/dm-thin.c
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@ -3101,6 +3101,7 @@ static int thin_ctr(struct dm_target *ti, unsigned argc, char **argv)
struct thin_c *tc;
struct dm_dev *pool_dev, *origin_dev;
struct mapped_device *pool_md;
unsigned long flags;
mutex_lock(&dm_thin_pool_table.mutex);
@ -3191,9 +3192,9 @@ static int thin_ctr(struct dm_target *ti, unsigned argc, char **argv)
mutex_unlock(&dm_thin_pool_table.mutex);
spin_lock(&tc->pool->lock);
spin_lock_irqsave(&tc->pool->lock, flags);
list_add_tail_rcu(&tc->list, &tc->pool->active_thins);
spin_unlock(&tc->pool->lock);
spin_unlock_irqrestore(&tc->pool->lock, flags);
/*
* This synchronize_rcu() call is needed here otherwise we risk a
* wake_worker() call finding no bios to process (because the newly