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| author | Prarit Bhargava <prarit@redhat.com> | 2017-08-28 14:21:53 +0200 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2017-09-25 21:05:59 +0200 |
| commit | 5df32107f609c1f621bcdac0a685c23677ef671e (patch) | |
| tree | b2905082b3a3f8d0a2d6049e6b6175620e4d724f /kernel | |
| parent | Linux 4.14-rc2 (diff) | |
| download | linux-5df32107f609c1f621bcdac0a685c23677ef671e.tar.xz linux-5df32107f609c1f621bcdac0a685c23677ef671e.zip | |
timekeeping: Make fast accessors return 0 before timekeeping is initialized
printk timestamps will be extended to include mono and boot time by using
the fast timekeeping accessors ktime_get_mono|boot_fast_ns(). The
functions can return garbage before timekeeping is initialized resulting in
garbage timestamps.
Initialize the fast timekeepers with dummy clocks which guarantee a 0
readout up to timekeeping_init().
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/1503922914-10660-2-git-send-email-prarit@redhat.com
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/time/timekeeping.c | 35 |
1 files 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. |