Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit c029a2be authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

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: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
Acked-by: default avatarPeter 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: default avatarThomas Gleixner <tglx@linutronix.de>
parent cbd99e3b

kernel/time/timekeeping.c

+5 −21
Original line number Original line Diff line number Diff line
@@ -1644,7 +1644,7 @@ void timekeeping_resume(void) 
	struct clocksource *clock = tk->tkr_mono.clock;

	struct clocksource *clock = tk->tkr_mono.clock;

	unsigned long flags;

	unsigned long flags;

	struct timespec64 ts_new, ts_delta;

	struct timespec64 ts_new, ts_delta;

	cycle_t cycle_now, cycle_delta;

	cycle_t cycle_now;





	sleeptime_injected = false;

	sleeptime_injected = false;

	read_persistent_clock64(&ts_new);

	read_persistent_clock64(&ts_new);
@@ -1670,27 +1670,11 @@ void timekeeping_resume(void) 
	cycle_now = tk->tkr_mono.read(clock);

	cycle_now = tk->tkr_mono.read(clock);

	if ((clock->flags & CLOCK_SOURCE_SUSPEND_NONSTOP) &&

	if ((clock->flags & CLOCK_SOURCE_SUSPEND_NONSTOP) &&

		cycle_now > tk->tkr_mono.cycle_last) {

		cycle_now > tk->tkr_mono.cycle_last) {

		u64 num, max = ULLONG_MAX;

		u64 nsec, cyc_delta;

		u32 mult = clock->mult;

		u32 shift = clock->shift;

		s64 nsec = 0;





		cycle_delta = clocksource_delta(cycle_now, tk->tkr_mono.cycle_last,

		cyc_delta = clocksource_delta(cycle_now, tk->tkr_mono.cycle_last,

					      tk->tkr_mono.mask);

					      tk->tkr_mono.mask);



		nsec = mul_u64_u32_shr(cyc_delta, clock->mult, clock->shift);

		/*

		 * "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;



		ts_delta = ns_to_timespec64(nsec);

		ts_delta = ns_to_timespec64(nsec);

		sleeptime_injected = true;

		sleeptime_injected = true;

	} else if (timespec64_compare(&ts_new, &timekeeping_suspend_time) > 0) {

	} else if (timespec64_compare(&ts_new, &timekeeping_suspend_time) > 0) {