diff options
| author | NeilBrown <neilb@suse.de> | 2011-09-21 15:30:20 +1000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-10-16 14:14:53 -0700 |
| commit | 7f3b5ef8184a929f56293d6c7a88f426c7b74558 (patch) | |
| tree | 817b10c76033ad291f9e5d5d56259855016ed190 /drivers/md/raid5.c | |
| parent | 57fb87f0a640cd7b2e7cde21fd7c13138f8ef75b (diff) | |
md: Avoid waking up a thread after it has been freed.
commit 01f96c0a9922cd9919baf9d16febdf7016177a12 upstream.
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/md/raid5.c')
| -rw-r--r-- | drivers/md/raid5.c | 6 |
1 files changed, 2 insertions, 4 deletions
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index b72edf35ec54..2581ba127354 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -5162,8 +5162,7 @@ static int run(mddev_t *mddev) return 0; abort: - md_unregister_thread(mddev->thread); - mddev->thread = NULL; + md_unregister_thread(&mddev->thread); if (conf) { print_raid5_conf(conf); free_conf(conf); @@ -5177,8 +5176,7 @@ static int stop(mddev_t *mddev) { raid5_conf_t *conf = mddev->private; - md_unregister_thread(mddev->thread); - mddev->thread = NULL; + md_unregister_thread(&mddev->thread); if (mddev->queue) mddev->queue->backing_dev_info.congested_fn = NULL; free_conf(conf); |