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tick: broadcast-hrtimer: Remove overly clever return value abuse 

commit b8a62f1ff0ccb18fdc25c6150d1cd394610f4753 upstream.

The assignment of bc_moved in the conditional construct relies on the
fact that in the case of hrtimer_start() invocation the return value
is always 0. It took me a while to understand it.

We want to get rid of the hrtimer_start() return value. Open code the
logic which makes it readable as well.

Change-Id: Ieca53b0b6ba6f94567329196da2e94f8c6b0fa09
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20150414203503.404751457@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[bwh: Backported to 3.16 to ease backporting commit b9023b91dd02
 "tick: broadcast-hrtimer: Fix a race in bc_set_next"]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
This commit is contained in:
Thomas Gleixner 2015-04-14 21:09:22 +00:00 committed by syphyr
parent 3a77014aa4
commit 39c00350fc
1 changed files with 5 additions and 3 deletions
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8
kernel/time/tick-broadcast-hrtimer.c
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@ -66,9 +66,11 @@ static int bc_set_next(ktime_t expires, struct clock_event_device *bc)
* hrtimer_{start/cancel} functions call into tracing,
* calls to these functions must be bound within RCU_NONIDLE.
*/
RCU_NONIDLE(bc_moved = (hrtimer_try_to_cancel(&bctimer) >= 0) ?
!hrtimer_start(&bctimer, expires, HRTIMER_MODE_ABS_PINNED) :
0);
RCU_NONIDLE({
bc_moved = hrtimer_try_to_cancel(&bctimer) >= 0;
if (bc_moved)
hrtimer_start(&bctimer, expires,
HRTIMER_MODE_ABS_PINNED);});
if (bc_moved) {
/* Bind the "device" to the cpu */
bc->bound_on = smp_processor_id();