In current kernel, there are several places which need to check
whether there is a persistent clock for the platform. Current check
is done by calling the read_persistent_clock() and validating the
return value.
Add such a flag to make code more readable and call read_persistent_clock()
only once for all the checks.
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: John Stultz <john.stu...@linaro.org>
Signed-off-by: Feng Tang <feng.t...@intel.com>
---
include/linux/time.h | 1 +
kernel/time/timekeeping.c | 15 +++++++++++----
2 files changed, 12 insertions(+), 4 deletions(-)
diff --git a/include/linux/time.h b/include/linux/time.h
index 4d358e9..19388ad 100644
--- a/include/linux/time.h
+++ b/include/linux/time.h
@@ -115,6 +115,7 @@ static inline bool timespec_valid_strict(const struct
timespec *ts)
return true;
}
+extern int persistent_clock_exist;
extern void read_persistent_clock(struct timespec *ts);
extern void read_boot_clock(struct timespec *ts);
extern int update_persistent_clock(struct timespec now);
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 4c7de02..b82f218 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -28,6 +28,9 @@ static struct timekeeper timekeeper;
/* flag for if timekeeping is suspended */
int __read_mostly timekeeping_suspended;
+/* Flag for if there is a persistent clock on this platform */
+int __read_mostly persistent_clock_exist;
+
static inline void tk_normalize_xtime(struct timekeeper *tk)
{
while (tk->xtime_nsec >= ((u64)NSEC_PER_SEC << tk->shift)) {
@@ -590,12 +593,14 @@ void __init timekeeping_init(void)
struct timespec now, boot, tmp;
read_persistent_clock(&now);
+
if (!timespec_valid_strict(&now)) {
pr_warn("WARNING: Persistent clock returned invalid value!\n"
" Check your CMOS/BIOS settings.\n");
now.tv_sec = 0;
now.tv_nsec = 0;
- }
+ } else if (now.tv_sec || now.tv_nsec)
+ persistent_clock_exist = 1;
read_boot_clock(&boot);
if (!timespec_valid_strict(&boot)) {
@@ -670,9 +675,11 @@ void timekeeping_inject_sleeptime(struct timespec *delta)
unsigned long flags;
struct timespec ts;
- /* Make sure we don't set the clock twice */
- read_persistent_clock(&ts);
- if (!(ts.tv_sec == 0 && ts.tv_nsec == 0))
+ /*
+ * Make sure we don't set the clock twice, as timekeeping_resume()
+ * already did it
+ */
+ if (persistent_clock_exist)
return;
write_seqlock_irqsave(&tk->lock, flags);
--
1.7.9.5
--
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