linux-kernel - [tip: timers/core] tick/rcu: Fix bogus ratelimit condition

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Date:   Sat, 10 Jun 2023 12:45:29 -0000
From:   "tip-bot2 for Wen Yang" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Wen Yang <wenyang.linux@...mail.com>,
        Thomas Gleixner <tglx@...utronix.de>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: timers/core] tick/rcu: Fix bogus ratelimit condition

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

Commit-ID:     5579a8a8f15bd08b731a015630daca6ccd0f8a14
Gitweb:        https://git.kernel.org/tip/5579a8a8f15bd08b731a015630daca6ccd0f8a14
Author:        Wen Yang <wenyang.linux@...mail.com>
AuthorDate:    Fri, 05 May 2023 00:12:53 +08:00
Committer:     Thomas Gleixner <tglx@...utronix.de>
CommitterDate: Sat, 10 Jun 2023 14:36:17 +02:00

tick/rcu: Fix bogus ratelimit condition

The ratelimit logic in report_idle_softirq() is broken because the
exit condition is always true:

	static int ratelimit;

	if (ratelimit < 10)
		return false;  ---> always returns here

	ratelimit++;           ---> no chance to run

Make it check for >= 10 instead.

Fixes: 0345691b24c0 ("tick/rcu: Stop allowing RCU_SOFTIRQ in idle")
Signed-off-by: Wen Yang <wenyang.linux@...mail.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Link: https://lore.kernel.org/r/tencent_5AAA3EEAB42095C9B7740BE62FBF9A67E007@qq.com

---
 kernel/time/tick-sched.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 5225467..8905505 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -1030,7 +1030,7 @@ static bool report_idle_softirq(void)
 			return false;
 	}
 
-	if (ratelimit < 10)
+	if (ratelimit >= 10)
 		return false;
 
 	/* On RT, softirqs handling may be waiting on some lock */