From: Guoqing Jiang guoqing.jiang@cloud.ionos.com
stable inclusion from stable-v5.10.122 commit 7eb32f286e6841ca091e737e5f8b02fee365d16c category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I5W6OE
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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[ 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 Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com Reviewed-by: Wei Li liwei391@huawei.com --- 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 2ecd4a782203..5f6f0ad0b108 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -7971,17 +7971,22 @@ 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); }