Commit-ID: 5df32107f609c1f621bcdac0a685c23677ef671e Gitweb: http://git.kernel.org/tip/5df32107f609c1f621bcdac0a685c23677ef671e Author: Prarit Bhargava <pra...@redhat.com> AuthorDate: Mon, 28 Aug 2017 08:21:53 -0400 Committer: Thomas Gleixner <t...@linutronix.de> CommitDate: Mon, 25 Sep 2017 21:05:59 +0200
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 <pet...@infradead.org> Signed-off-by: Prarit Bhargava <pra...@redhat.com> Signed-off-by: Thomas Gleixner <t...@linutronix.de> Cc: Stephen Boyd <sb...@codeaurora.org> Cc: John Stultz <john.stu...@linaro.org> Link: http://lkml.kernel.org/r/1503922914-10660-2-git-send-email-pra...@redhat.com --- 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 2cafb49..6a92794 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.
