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Subject[PATCH v2] PM: Use 64-bit timekeeping
The freezer try_to_freeze_tasks uses 'struct timeval' for start
and end times, tracking time taken to freeze tasks. 'struct timeval'
on 32-bit systems will have its tv_sec overflow in year 2038 and
beyond. This patches uses 'ktime_t' (which has 64 bit values
for seconds) for start and end time.

Suggested-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Tina Ruchandani <ruchandani.tina@gmail.com>
---
Changes in v2:
- Use ktime_t to be able to use ktime_ms_delta
which is more efficient than timespec64 based methods.
---
kernel/power/process.c | 12 +++++-------
1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/kernel/power/process.c b/kernel/power/process.c
index 5a6ec86..52414dd 100644
--- a/kernel/power/process.c
+++ b/kernel/power/process.c
@@ -17,6 +17,7 @@
#include <linux/delay.h>
#include <linux/workqueue.h>
#include <linux/kmod.h>
+#include <linux/ktime.h>
#include <trace/events/power.h>

/*
@@ -30,13 +31,12 @@ static int try_to_freeze_tasks(bool user_only)
unsigned long end_time;
unsigned int todo;
bool wq_busy = false;
- struct timeval start, end;
- u64 elapsed_msecs64;
+ ktime_t start, end;
unsigned int elapsed_msecs;
bool wakeup = false;
int sleep_usecs = USEC_PER_MSEC;

- do_gettimeofday(&start);
+ start = ktime_get();

end_time = jiffies + msecs_to_jiffies(freeze_timeout_msecs);

@@ -78,10 +78,8 @@ static int try_to_freeze_tasks(bool user_only)
sleep_usecs *= 2;
}

- do_gettimeofday(&end);
- elapsed_msecs64 = timeval_to_ns(&end) - timeval_to_ns(&start);
- do_div(elapsed_msecs64, NSEC_PER_MSEC);
- elapsed_msecs = elapsed_msecs64;
+ end = ktime_get();
+ elapsed_msecs = (unsigned int) ktime_ms_delta(end, start);

if (todo) {
printk("\n");
--
2.2.0.rc0.207.ga3a616c


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