linux-kernel - [PATCH AUTOSEL 6.1 065/212] posix-timers: Add cond_resched() to posix_timer

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Message-Id: <20250505230624.2692522-65-sashal@kernel.org>
Date: Mon,  5 May 2025 19:03:57 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Eric Dumazet <edumazet@...gle.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Frederic Weisbecker <frederic@...nel.org>,
	Sasha Levin <sashal@...nel.org>,
	anna-maria@...utronix.de
Subject: [PATCH AUTOSEL 6.1 065/212] posix-timers: Add cond_resched() to posix_timer_add() search loop

From: Eric Dumazet <edumazet@...gle.com>

[ Upstream commit 5f2909c6cd13564a07ae692a95457f52295c4f22 ]

With a large number of POSIX timers the search for a valid ID might cause a
soft lockup on PREEMPT_NONE/VOLUNTARY kernels.

Add cond_resched() to the loop to prevent that.

[ tglx: Split out from Eric's series ]

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Reviewed-by: Frederic Weisbecker <frederic@...nel.org>
Link: https://lore.kernel.org/all/20250214135911.2037402-2-edumazet@google.com
Link: https://lore.kernel.org/all/20250308155623.635612865@linutronix.de
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 kernel/time/posix-timers.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index 2d6cf93ca370a..fc08d4ccdeeb9 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -161,6 +161,7 @@ static int posix_timer_add(struct k_itimer *timer)
 			return id;
 		}
 		spin_unlock(&hash_lock);
+		cond_resched();
 	}
 	/* POSIX return code when no timer ID could be allocated */
 	return -EAGAIN;
-- 
2.39.5