From: Thomas Gleixner <tglx@linutronix.de>
Date: Sun, 15 Aug 2021 21:29:10 +0000 (+0200)
Subject: futex: Correct the number of requeued waiters for PI
X-Git-Tag: v5.15-rc1~119^2~14
X-Git-Url: https://gentwo.org/gitweb/?a=commitdiff_plain;h=59c7ecf1544e1841b5be8847e81bc9842f838e7e;p=linux%2F.git

futex: Correct the number of requeued waiters for PI

The accounting is wrong when either the PI sanity check or the
requeue PI operation fails. Adjust it in the failure path.

Will be simplified in the next step.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210815211305.416427548@linutronix.de
---

diff --git a/kernel/futex.c b/kernel/futex.c
index 8ddc87cae25c..543974285676 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -2116,6 +2116,8 @@ static int futex_requeue(u32 __user *uaddr1, unsigned int flags,
 
 		/* Ensure we requeue to the expected futex for requeue_pi. */
 		if (requeue_pi && !match_futex(this->requeue_pi_key, &key2)) {
+			/* Don't account for it */
+			task_count--;
 			ret = -EINVAL;
 			break;
 		}
@@ -2157,6 +2159,8 @@ static int futex_requeue(u32 __user *uaddr1, unsigned int flags,
 				 */
 				this->pi_state = NULL;
 				put_pi_state(pi_state);
+				/* Don't account for it */
+				task_count--;
 				/*
 				 * We stop queueing more waiters and let user
 				 * space deal with the mess.