linux-kernel - [tip: timers/core] posix-timers: Add cond_resched() to posix_timer

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Message-ID: <174186549360.14745.8639976419196139513.tip-bot2@tip-bot2>
Date: Thu, 13 Mar 2025 11:31:33 -0000
From: "tip-bot2 for Eric Dumazet" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Eric Dumazet <edumazet@...gle.com>, Thomas Gleixner <tglx@...utronix.de>,
 Frederic Weisbecker <frederic@...nel.org>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: timers/core] posix-timers: Add cond_resched() to
 posix_timer_add() search loop

The following commit has been merged into the timers/core branch of tip:

Commit-ID:     5f2909c6cd13564a07ae692a95457f52295c4f22
Gitweb:        https://git.kernel.org/tip/5f2909c6cd13564a07ae692a95457f52295c4f22
Author:        Eric Dumazet <edumazet@...gle.com>
AuthorDate:    Sat, 08 Mar 2025 17:48:17 +01:00
Committer:     Thomas Gleixner <tglx@...utronix.de>
CommitterDate: Thu, 13 Mar 2025 12:07:16 +01:00

posix-timers: Add cond_resched() to posix_timer_add() search loop

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


---
 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 24d7eab..de25253 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -144,6 +144,7 @@ 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;