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| author | Jun'ichi Nomura <j-nomura@ce.jp.nec.com> | 2005-09-09 16:23:42 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2005-09-09 16:39:09 -0700 |
| commit | 844e8d904a7c1446e3f040683b4a0645c3eb168f (patch) | |
| tree | 5e277539dab95d6325cec564a91e0e70acdce021 /drivers/md | |
| parent | e5dcdd80a60627371f40797426273048630dc8ca (diff) | |
| download | op-kernel-dev-844e8d904a7c1446e3f040683b4a0645c3eb168f.zip op-kernel-dev-844e8d904a7c1446e3f040683b4a0645c3eb168f.tar.gz | |
[PATCH] dm: fix rh_dec()/rh_inc() race in dm-raid1.c
Fix another bug in dm-raid1.c that the dirty region may stay in or be moved
to clean list and freed while in use.
It happens as follows:
CPU0 CPU1
------------------------------------------------------------------------------
rh_dec()
if (atomic_dec_and_test(pending))
<the region is still marked dirty>
rh_inc()
if the region is clean
mark the region dirty
and remove from clean list
mark the region clean
and move to clean list
atomic_inc(pending)
At this stage, the region is in clean list and will be mistakenly reclaimed
by rh_update_states() later.
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'drivers/md')
| -rw-r--r-- | drivers/md/dm-raid1.c | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c index b08df8b..8632825 100644 --- a/drivers/md/dm-raid1.c +++ b/drivers/md/dm-raid1.c @@ -375,16 +375,18 @@ static void rh_inc(struct region_hash *rh, region_t region) read_lock(&rh->hash_lock); reg = __rh_find(rh, region); + + atomic_inc(®->pending); + + spin_lock_irq(&rh->region_lock); if (reg->state == RH_CLEAN) { rh->log->type->mark_region(rh->log, reg->key); - spin_lock_irq(&rh->region_lock); reg->state = RH_DIRTY; list_del_init(®->list); /* take off the clean list */ - spin_unlock_irq(&rh->region_lock); } + spin_unlock_irq(&rh->region_lock); - atomic_inc(®->pending); read_unlock(&rh->hash_lock); } @@ -408,6 +410,10 @@ static void rh_dec(struct region_hash *rh, region_t region) if (atomic_dec_and_test(®->pending)) { spin_lock_irqsave(&rh->region_lock, flags); + if (atomic_read(®->pending)) { /* check race */ + spin_unlock_irqrestore(&rh->region_lock, flags); + return; + } if (reg->state == RH_RECOVERING) { list_add_tail(®->list, &rh->quiesced_regions); } else { |
