diff options
| author | Guoqing Jiang <guoqing.jiang@cloud.ionos.com> | 2022-04-29 11:49:09 +0300 |
|---|---|---|
| committer | Song Liu <song@kernel.org> | 2022-05-23 09:07:21 +0300 |
| commit | 1e267742283a4b5a8ca65755c44166be27e9aa0f (patch) | |
| tree | 58e8575c119e1b6b69a440ccfee1efdb69a54611 /drivers/md/md.c | |
| parent | 8b48ec23cc51a4e7c8dbaef5f34ebe67e1a80934 (diff) | |
| download | linux-1e267742283a4b5a8ca65755c44166be27e9aa0f.tar.xz | |
md: protect md_unregister_thread from reentrancy
Generally, the md_unregister_thread is called with reconfig_mutex, but
raid_message in dm-raid doesn't hold reconfig_mutex to unregister thread,
so md_unregister_thread can be called simulitaneously from two call sites
in theory.
Then after previous commit which remove the protection of reconfig_mutex
for md_unregister_thread completely, the potential issue could be worse
than before.
Let's take pers_lock at the beginning of function to ensure reentrancy.
Reported-by: Donald Buczek <buczek@molgen.mpg.de>
Signed-off-by: Guoqing Jiang <guoqing.jiang@linux.dev>
Signed-off-by: Song Liu <song@kernel.org>
Diffstat (limited to 'drivers/md/md.c')
| -rw-r--r-- | drivers/md/md.c | 15 |
1 files changed, 10 insertions, 5 deletions
diff --git a/drivers/md/md.c b/drivers/md/md.c index 1958a14a0c79..53787a32166d 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -7963,17 +7963,22 @@ EXPORT_SYMBOL(md_register_thread); void md_unregister_thread(struct md_thread **threadp) { - struct md_thread *thread = *threadp; - if (!thread) - return; - pr_debug("interrupting MD-thread pid %d\n", task_pid_nr(thread->tsk)); - /* Locking ensures that mddev_unlock does not wake_up a + struct md_thread *thread; + + /* + * Locking ensures that mddev_unlock does not wake_up a * non-existent thread */ spin_lock(&pers_lock); + thread = *threadp; + if (!thread) { + spin_unlock(&pers_lock); + return; + } *threadp = NULL; spin_unlock(&pers_lock); + pr_debug("interrupting MD-thread pid %d\n", task_pid_nr(thread->tsk)); kthread_stop(thread->tsk); kfree(thread); } |