[patch 07/10] ipc/sem: do not sleep with a spin lock held

[Andrew Morton <akpm@linux-foundation.org>]

From: Minghao Chi <chi.minghao@zte.com.cn>
Subject: ipc/sem: do not sleep with a spin lock held

We can't call kvfree() with a spin lock held, so defer it.

Link: https://lkml.kernel.org/r/20211223031207.556189-1-chi.minghao@zte.com.cn
Fixes: fc37a3b8b438 ("[PATCH] ipc sem: use kvmalloc for sem_undo allocation")
Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: Minghao Chi <chi.minghao@zte.com.cn>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Manfred Spraul <manfred@colorfullife.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Yang Guang <cgel.zte@gmail.com>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Bhaskar Chowdhury <unixbhaskar@gmail.com>
Cc: Vasily Averin <vvs@virtuozzo.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 ipc/sem.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/ipc/sem.c~ipc-sem-do-not-sleep-with-a-spin-lock-held
+++ a/ipc/sem.c
@@ -1964,6 +1964,7 @@ static struct sem_undo *find_alloc_undo(
 	 */
 	un = lookup_undo(ulp, semid);
 	if (un) {
+		spin_unlock(&ulp->lock);
 		kvfree(new);
 		goto success;
 	}
@@ -1976,9 +1977,8 @@ static struct sem_undo *find_alloc_undo(
 	ipc_assert_locked_object(&sma->sem_perm);
 	list_add(&new->list_id, &sma->list_id);
 	un = new;
-
-success:
 	spin_unlock(&ulp->lock);
+success:
 	sem_unlock(sma, -1);
 out:
 	return un;
_