linux-kernel - [PATCH] ipc/sem: do not sleep with a spin lock held

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Date:   Wed, 22 Dec 2021 08:10:26 +0000
From:   cgel.zte@...il.com
To:     akpm@...ux-foundation.org
Cc:     vvs@...tuozzo.com, shakeelb@...gle.com, rdunlap@...radead.org,
        dbueso@...e.de, unixbhaskar@...il.com, manfred@...orfullife.com,
        chi.minghao@....com.cn, arnd@...db.de,
        linux-kernel@...r.kernel.org, Zeal Robot <zealci@....com.cn>
Subject: [PATCH] ipc/sem: do not sleep with a spin lock held

From: Minghao Chi <chi.minghao@....com.cn>

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

Reported-by: Zeal Robot <zealci@....com.cn>
Signed-off-by: Minghao Chi <chi.minghao@....com.cn>
---
 ipc/sem.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/ipc/sem.c b/ipc/sem.c
index 6693daf4fe11..0dbdb98fdf2d 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -1964,6 +1964,7 @@ static struct sem_undo *find_alloc_undo(struct ipc_namespace *ns, int semid)
 	 */
 	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(struct ipc_namespace *ns, int semid)
 	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;
-- 
2.25.1