Messages in this thread Patch in this message |  | | From | Prarit Bhargava <> | Subject | [PATCH 1/2 v9] time: Make fast functions return 0 before timekeeping is initialized | Date | Fri, 25 Aug 2017 13:20:18 -0400 |
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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.
Signed-off-by: Prarit Bhargava <prarit@redhat.com> Suggested-by: Peter Zijlstra <peterz@infradead.org> Cc: John Stultz <john.stultz@linaro.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Stephen Boyd <sboyd@codeaurora.org> --- kernel/time/timekeeping.c | 47 +++++++++++++++++++++++++++++++++-------------- 1 file changed, 33 insertions(+), 14 deletions(-)
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index cedafa008de5..d111039e0245 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -60,8 +60,39 @@ 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 = { + (struct tk_read_base){ + .clock = &dummy_clock, + }, + (struct tk_read_base){ + .clock = &dummy_clock, + }, + }, +}; + +static struct tk_fast tk_fast_raw ____cacheline_aligned = { + .base = { + (struct tk_read_base){ + .clock = &dummy_clock, + }, + (struct tk_read_base){ + .clock = &dummy_clock, + }, + }, +}; /* flag for if timekeeping is suspended */ int __read_mostly timekeeping_suspended; @@ -477,18 +508,6 @@ 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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