linux-kernel - [PATCH] x86/aperfmperf: use time_is_before_jiffies(a + b) to replace "jiffies

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Message-Id: <20220727031405.26892-1-yuzhe@nfschina.com>
Date:   Wed, 27 Jul 2022 11:14:05 +0800
From:   Yu Zhe <yuzhe@...china.com>
To:     tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
        dave.hansen@...ux.intel.com, x86@...nel.org, hpa@...or.com
Cc:     linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        liqiong@...china.com, Yu Zhe <yuzhe@...china.com>
Subject: [PATCH] x86/aperfmperf: use time_is_before_jiffies(a + b) to replace "jiffies - a > b"

time_is_before_jiffies deals with timer wrapping correctly.

Signed-off-by: Yu Zhe <yuzhe@...china.com>
---
 arch/x86/kernel/cpu/aperfmperf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/aperfmperf.c b/arch/x86/kernel/cpu/aperfmperf.c
index 1f60a2b27936..22e0bac3fffe 100644
--- a/arch/x86/kernel/cpu/aperfmperf.c
+++ b/arch/x86/kernel/cpu/aperfmperf.c
@@ -423,7 +423,7 @@ unsigned int arch_freq_get_on_cpu(int cpu)
 	 * Bail on invalid count and when the last update was too long ago,
 	 * which covers idle and NOHZ full CPUs.
 	 */
-	if (!mcnt || (jiffies - last) > MAX_SAMPLE_AGE)
+	if (!mcnt || time_is_before_jiffies(last + MAX_SAMPLE_AGE))
 		goto fallback;
 
 	return div64_u64((cpu_khz * acnt), mcnt);
-- 
2.11.0