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/md.h | |
| 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/md.h')
| -rw-r--r-- | drivers/md/md.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/md/md.h b/drivers/md/md.h index 1c26c7a08ae..ce4e328049d 100644 --- a/drivers/md/md.h +++ b/drivers/md/md.h @@ -475,7 +475,7 @@ extern int register_md_personality(struct mdk_personality *p); extern int unregister_md_personality(struct mdk_personality *p); extern mdk_thread_t * md_register_thread(void (*run) (mddev_t *mddev), mddev_t *mddev, const char *name); -extern void md_unregister_thread(mdk_thread_t *thread); +extern void md_unregister_thread(mdk_thread_t **threadp); extern void md_wakeup_thread(mdk_thread_t *thread); extern void md_check_recovery(mddev_t *mddev); extern void md_write_start(mddev_t *mddev, struct bio *bi); |