From: Guoqing Jiang guoqing.jiang@cloud.ionos.com
[ Upstream commit 1e267742283a4b5a8ca65755c44166be27e9aa0f ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/md/md.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-)
diff --git a/drivers/md/md.c b/drivers/md/md.c index b553654cbebc..bf1c5c0e472e 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -7942,17 +7942,22 @@ 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); }