Commit-ID: 5df32107f609c1f621bcdac0a685c23677ef671e
Gitweb: http://git.kernel.org/tip/5df32107f609c1f621bcdac0a685c23677ef671e
Author: Prarit Bhargava <prarit@xxxxxxxxxx>
AuthorDate: Mon, 28 Aug 2017 08:21:53 -0400
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
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 <peterz@xxxxxxxxxxxxx>
Signed-off-by: Prarit Bhargava <prarit@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Stephen Boyd <sboyd@xxxxxxxxxxxxxx>
Cc: John Stultz <john.stultz@xxxxxxxxxx>
Link: http://lkml.kernel.org/r/1503922914-10660-2-git-send-email-prarit@xxxxxxxxxx
---
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.
--
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