diff options
| author | NeilBrown <neilb@suse.de> | 2011-09-21 15:30:20 +1000 |
|---|---|---|
| committer | NeilBrown <neilb@suse.de> | 2011-09-21 15:30:20 +1000 |
| commit | 01f96c0a9922cd9919baf9d16febdf7016177a12 (patch) | |
| tree | a877fe509c4ef0db5252b7192df56009c1d06d6f /drivers/md/raid10.c | |
| parent | 27a7b260f71439c40546b43588448faac01adb93 (diff) | |
md: Avoid waking up a thread after it has been freed.
Two related problems:
1/ some error paths call "md_unregister_thread(mddev->thread)"
without subsequently clearing ->thread. A subsequent call
to mddev_unlock will try to wake the thread, and crash.
2/ Most calls to md_wakeup_thread are protected against the thread
disappeared either by:
- holding the ->mutex
- having an active request, so something else must be keeping
the array active.
However mddev_unlock calls md_wakeup_thread after dropping the
mutex and without any certainty of an active request, so the
->thread could theoretically disappear.
So we need a spinlock to provide some protections.
So change md_unregister_thread to take a pointer to the thread
pointer, and ensure that it always does the required locking, and
clears the pointer properly.
Reported-by: "Moshe Melnikov" <moshe@zadarastorage.com>
Signed-off-by: NeilBrown <neilb@suse.de>
cc: stable@kernel.org
Diffstat (limited to 'drivers/md/raid10.c')
| -rw-r--r-- | drivers/md/raid10.c | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c index d7a8468ddeab..0cd9672cf9cb 100644 --- a/drivers/md/raid10.c +++ b/drivers/md/raid10.c @@ -2955,7 +2955,7 @@ static int run(mddev_t *mddev) return 0; out_free_conf: - md_unregister_thread(mddev->thread); + md_unregister_thread(&mddev->thread); if (conf->r10bio_pool) mempool_destroy(conf->r10bio_pool); safe_put_page(conf->tmppage); @@ -2973,8 +2973,7 @@ static int stop(mddev_t *mddev) raise_barrier(conf, 0); lower_barrier(conf); - md_unregister_thread(mddev->thread); - mddev->thread = NULL; + md_unregister_thread(&mddev->thread); blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/ if (conf->r10bio_pool) mempool_destroy(conf->r10bio_pool); |