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Date: Mon, 18 Sep 2017 13:50:58 -0400 From: Prarit Bhargava <prarit@...hat.com> To: linux-kernel@...r.kernel.org Cc: Prarit Bhargava <prarit@...hat.com>, John Stultz <john.stultz@...aro.org>, Thomas Gleixner <tglx@...utronix.de>, Stephen Boyd <sboyd@...eaurora.org> Subject: [PATCH 1/3 v12] time: Make fast functions return 0 before timekeeping is initialized printk timestamps will be extended to include mono and boot time by using the fast timekeeping functions ktime_get_mono|boot_fast_ns() functions. The functions can return garbage before timekeeping is initialized resulting in garbage timestamps. The fast time functions must return 0 before timekeeping is initialized. [v12]: Remove typecast. Signed-off-by: Prarit Bhargava <prarit@...hat.com> Suggested-by: Peter Zijlstra <peterz@...radead.org> Cc: John Stultz <john.stultz@...aro.org> Cc: Thomas Gleixner <tglx@...utronix.de> Cc: Stephen Boyd <sboyd@...eaurora.org> --- kernel/time/timekeeping.c | 35 +++++++++++++++++++++-------------- 1 file changed, 21 insertions(+), 14 deletions(-) diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 2cafb49aa65e..6a92794427c9 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -60,8 +60,27 @@ struct tk_fast { struct tk_read_base base[2]; }; -static struct tk_fast tk_fast_mono ____cacheline_aligned; -static struct tk_fast tk_fast_raw ____cacheline_aligned; +/* Suspend-time cycles value for halted fast timekeeper. */ +static u64 cycles_at_suspend; + +static u64 dummy_clock_read(struct clocksource *cs) +{ + return cycles_at_suspend; +} + +static struct clocksource dummy_clock = { + .read = dummy_clock_read, +}; + +static struct tk_fast tk_fast_mono ____cacheline_aligned = { + .base[0] = { .clock = &dummy_clock, }, + .base[1] = { .clock = &dummy_clock, }, +}; + +static struct tk_fast tk_fast_raw ____cacheline_aligned = { + .base[0] = { .clock = &dummy_clock, }, + .base[1] = { .clock = &dummy_clock, }, +}; /* flag for if timekeeping is suspended */ int __read_mostly timekeeping_suspended; @@ -477,18 +496,6 @@ u64 notrace ktime_get_boot_fast_ns(void) } EXPORT_SYMBOL_GPL(ktime_get_boot_fast_ns); -/* Suspend-time cycles value for halted fast timekeeper. */ -static u64 cycles_at_suspend; - -static u64 dummy_clock_read(struct clocksource *cs) -{ - return cycles_at_suspend; -} - -static struct clocksource dummy_clock = { - .read = dummy_clock_read, -}; - /** * halt_fast_timekeeper - Prevent fast timekeeper from accessing clocksource. * @tk: Timekeeper to snapshot. -- 1.8.5.5
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