From: Yang Yingliang <yangyingliang@huawei.com>
To: <linux-arm-kernel@lists.infradead.org>, <linux-kernel@vger.kernel.org>
Cc: Yang Yingliang <yangyingliang@huawei.com>,
Thomas Gleixner <tglx@linutronix.de>
Subject: [PATCH 0/2] validate the delta of cycle_now and cycle_last on arm64
Date: Tue, 27 Oct 2015 21:21:11 +0800 [thread overview]
Message-ID: <1445952073-7260-1-git-send-email-yangyingliang@huawei.com> (raw)
In multi-core system, if the clock is not sync perfectly, it
will make cycle_last that recorded by CPU-A is a little more
than cycle_now that read by CPU-B. With the negative result,
hrtimer_update_base() return a huge and wrong time. It leads
to the cpu can not finish the while loop in hrtimer_interrupt()
until the real nowtime which is returned from ktime_get() catch
up with the wrong time on clock monotonic base.
Fix it by select config CLOCKSOURCE_VALIDATE_LAST_CYCLE.
Cc: Thomas Gleixner <tglx@linutronix.de>
Yang Yingliang (2):
clocksource: replace cycle_last validation with an equal way
arm64: validate the cycle_last to prevent time going backwards
arch/arm64/Kconfig | 1 +
kernel/time/timekeeping_internal.h | 2 +-
2 files changed, 2 insertions(+), 1 deletion(-)
--
2.5.0
next reply other threads:[~2015-10-27 13:22 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-27 13:21 Yang Yingliang [this message]
2015-10-27 13:21 ` [PATCH 1/2] clocksource: replace cycle_last validation with an equal way Yang Yingliang
2015-10-30 14:56 ` Thomas Gleixner
2015-10-31 10:07 ` Yang Yingliang
2015-10-31 10:20 ` [PATCH resend] clocksource: modify the cycle_last validation to fit for non-64bit clocksourece mask Yang Yingliang
2015-12-19 15:03 ` [tip:timers/core] clocksource: Make clocksource validation work for all clocksources tip-bot for Yang Yingliang
2016-01-04 17:13 ` John Stultz
2015-10-27 13:21 ` [PATCH 2/2] arm64: validate the delta of cycle_now and cycle_last Yang Yingliang
2015-10-27 14:03 ` Mark Rutland
2015-10-28 1:33 ` Ding Tianhong
2015-10-29 7:36 ` Yang Yingliang
2015-10-29 8:31 ` Yang Yingliang
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