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| author | Thomas Gleixner <tglx@linutronix.de> | 2016-12-08 20:49:38 +0000 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2016-12-09 12:06:42 +0100 |
| commit | c029a2bec66e42e57538cb65e28618baf6a4b311 (patch) | |
| tree | 44a053f24b8ab7f3a81826d181499aa0513b8812 /kernel/time | |
| parent | cbd99e3b289e43000c29aa4aa9b94b394cdc68bd (diff) | |
| download | linux-c029a2bec66e42e57538cb65e28618baf6a4b311.tar.gz linux-c029a2bec66e42e57538cb65e28618baf6a4b311.tar.xz | |
timekeeping: Use mul_u64_u32_shr() instead of open coding it
The resume code must deal with a clocksource delta which is potentially big
enough to overflow the 64bit mult.
Replace the open coded handling with the proper function.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Parit Bhargava <prarit@redhat.com>
Cc: Laurent Vivier <lvivier@redhat.com>
Cc: "Christopher S. Hall" <christopher.s.hall@intel.com>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Liav Rehana <liavr@mellanox.com>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/20161208204228.921674404@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel/time')
| -rw-r--r-- | kernel/time/timekeeping.c | 26 |
1 files changed, 5 insertions, 21 deletions
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 82e1b5cbebbb..da233cdf89b0 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -1644,7 +1644,7 @@ void timekeeping_resume(void) struct clocksource *clock = tk->tkr_mono.clock; unsigned long flags; struct timespec64 ts_new, ts_delta; - cycle_t cycle_now, cycle_delta; + cycle_t cycle_now; sleeptime_injected = false; read_persistent_clock64(&ts_new); @@ -1670,27 +1670,11 @@ void timekeeping_resume(void) cycle_now = tk->tkr_mono.read(clock); if ((clock->flags & CLOCK_SOURCE_SUSPEND_NONSTOP) && cycle_now > tk->tkr_mono.cycle_last) { - u64 num, max = ULLONG_MAX; - u32 mult = clock->mult; - u32 shift = clock->shift; - s64 nsec = 0; - - cycle_delta = clocksource_delta(cycle_now, tk->tkr_mono.cycle_last, - tk->tkr_mono.mask); - - /* - * "cycle_delta * mutl" may cause 64 bits overflow, if the - * suspended time is too long. In that case we need do the - * 64 bits math carefully - */ - do_div(max, mult); - if (cycle_delta > max) { - num = div64_u64(cycle_delta, max); - nsec = (((u64) max * mult) >> shift) * num; - cycle_delta -= num * max; - } - nsec += ((u64) cycle_delta * mult) >> shift; + u64 nsec, cyc_delta; + cyc_delta = clocksource_delta(cycle_now, tk->tkr_mono.cycle_last, + tk->tkr_mono.mask); + nsec = mul_u64_u32_shr(cyc_delta, clock->mult, clock->shift); ts_delta = ns_to_timespec64(nsec); sleeptime_injected = true; } else if (timespec64_compare(&ts_new, &timekeeping_suspend_time) > 0) { |