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Subject[PATCH 1/3 v11] time: Make fast functions return 0 before timekeeping is initialized
Date
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 7e7e61c00d61..1f8596ef7408 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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