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From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
	John Stultz <john.stultz@linaro.org>,
	Stephen Boyd <sboyd@kernel.org>
Subject: [patch 1/3] timekeeping: Annotate ktime_get_boot_fast_ns() with data_race()
Date: Fri, 15 Apr 2022 11:19:35 +0200 (CEST)	[thread overview]
Message-ID: <20220415091920.956045162@linutronix.de> (raw)
In-Reply-To: 20220415091223.187169221@linutronix.de

Accessing timekeeper::offset_boot in ktime_get_boot_fast_ns() is an
intended data race as the reader side cannot synchronize with a writer and
there is no space in struct tk_read_base of the NMI safe timekeeper.

Mark it so.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 kernel/time/timekeeping.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -528,7 +528,7 @@ u64 notrace ktime_get_boot_fast_ns(void)
 {
 	struct timekeeper *tk = &tk_core.timekeeper;
 
-	return (ktime_get_mono_fast_ns() + ktime_to_ns(tk->offs_boot));
+	return (ktime_get_mono_fast_ns() + ktime_to_ns(data_race(tk->offs_boot)));
 }
 EXPORT_SYMBOL_GPL(ktime_get_boot_fast_ns);
 


  reply	other threads:[~2022-04-15  9:19 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-15  9:19 [patch 0/3] timekeeping: Janitorial updates Thomas Gleixner
2022-04-15  9:19 ` Thomas Gleixner [this message]
2022-04-15 12:07   ` [patch 1/3] timekeeping: Annotate ktime_get_boot_fast_ns() with data_race() Peter Zijlstra
2022-04-15 21:46     ` Thomas Gleixner
2022-05-02 12:04   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2022-04-15  9:19 ` [patch 2/3] timekeeping: Mark tk_clock_read() __always_inline Thomas Gleixner
2022-04-15 12:09   ` Peter Zijlstra
2022-04-15 21:48     ` Thomas Gleixner
2022-04-15  9:19 ` [patch 3/3] timekeeping: Consolidate fast timekeeper Thomas Gleixner
2022-04-15 12:09   ` Peter Zijlstra
2022-05-02 12:04   ` [tip: timers/core] " tip-bot2 for Thomas Gleixner

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