Commit 7692c5dd authored by Jonathan E Brassow's avatar Jonathan E Brassow Committed by Linus Torvalds
Browse files

[PATCH] device-mapper raid1: drop mark_region spinlock fix 



The spinlock region_lock is held while calling mark_region which can sleep.
Drop the spinlock before calling that function.

A region's state and inclusion in the clean list are altered by rh_inc and
rh_dec.  The state variable is set to RH_CLEAN in rh_dec, but only if
'pending' is zero.  It is set to RH_DIRTY in rh_inc, but not if it is already
so.  The changes to 'pending', the state, and the region's inclusion in the
clean list need to be atomicly.

Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 233886dd

drivers/md/dm-raid1.c

+9 −11
Original line number Diff line number Diff line
@@ -376,17 +376,19 @@ static void rh_inc(struct region_hash *rh, region_t region) 
	read_lock(&rh->hash_lock);

	reg = __rh_find(rh, region);



	spin_lock_irq(&rh->region_lock);

	atomic_inc(&reg->pending);



	spin_lock_irq(&rh->region_lock);

	if (reg->state == RH_CLEAN) {

		rh->log->type->mark_region(rh->log, reg->key);



		reg->state = RH_DIRTY;

		list_del_init(&reg->list);	/* take off the clean list */

	}

		spin_unlock_irq(&rh->region_lock);



		rh->log->type->mark_region(rh->log, reg->key);

	} else

		spin_unlock_irq(&rh->region_lock);





	read_unlock(&rh->hash_lock);

}
@@ -408,21 +410,17 @@ static void rh_dec(struct region_hash *rh, region_t region) 
	reg = __rh_lookup(rh, region);

	read_unlock(&rh->hash_lock);



	if (atomic_dec_and_test(&reg->pending)) {

	spin_lock_irqsave(&rh->region_lock, flags);

		if (atomic_read(&reg->pending)) { /* check race */

			spin_unlock_irqrestore(&rh->region_lock, flags);

			return;

		}

	if (atomic_dec_and_test(&reg->pending)) {

		if (reg->state == RH_RECOVERING) {

			list_add_tail(&reg->list, &rh->quiesced_regions);

		} else {

			reg->state = RH_CLEAN;

			list_add(&reg->list, &rh->clean_regions);

		}

		spin_unlock_irqrestore(&rh->region_lock, flags);

		should_wake = 1;

	}

	spin_unlock_irqrestore(&rh->region_lock, flags);



	if (should_wake)

		wake();

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