linux-kernel - [tip: timers/core] timekeeping: Annotate ktime_get_boot_fast_ns() with data

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Date:   Mon, 02 May 2022 12:04:32 -0000
From:   "tip-bot2 for Thomas Gleixner" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Thomas Gleixner <tglx@...utronix.de>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: timers/core] timekeeping: Annotate ktime_get_boot_fast_ns()
 with data_race()

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

Commit-ID:     eff4849f928f2b90402907e06a6de1619cf16b1a
Gitweb:        https://git.kernel.org/tip/eff4849f928f2b90402907e06a6de1619cf16b1a
Author:        Thomas Gleixner <tglx@...utronix.de>
AuthorDate:    Fri, 15 Apr 2022 11:19:35 +02:00
Committer:     Thomas Gleixner <tglx@...utronix.de>
CommitterDate: Mon, 02 May 2022 14:00:20 +02:00

timekeeping: Annotate ktime_get_boot_fast_ns() with data_race()

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@...utronix.de>
Link: https://lore.kernel.org/r/20220415091920.956045162@linutronix.de

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

diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 2c22023..3479804 100644
--- 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);