Commit bbe9a70a authored Apr 09, 2018 by Arnd Bergmann Committed by Rafael J. Wysocki Apr 10, 2018

tick-sched: avoid a maybe-uninitialized warning

The use of bitfields seems to confuse gcc, leading to a false-positive
warning in all compiler versions:

kernel/time/tick-sched.c: In function 'tick_nohz_idle_exit':
kernel/time/tick-sched.c:538:2: error: 'now' may be used uninitialized in this function [-Werror=maybe-uninitialized]

This introduces a temporary variable to track the flags so gcc
doesn't have to evaluate twice, eliminating the code path that
leads to the warning.

Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85301


Fixes: 1cae544d42d2 ("nohz: Gather tick_sched booleans under a common flag field")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

parent 792ccb45

kernel/time/tick-sched.c

+6 −3

Original line number	Diff line number	Diff line
		@@ -1134,6 +1134,7 @@ void tick_nohz_idle_restart_tick(void)
		void tick_nohz_idle_exit(void)
		{
		struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched);
		bool idle_active, tick_stopped;
		ktime_t now;

		local_irq_disable();
		@@ -1142,14 +1143,16 @@ void tick_nohz_idle_exit(void)
		WARN_ON_ONCE(ts->timer_expires_base);

		ts->inidle = 0;
		idle_active = ts->idle_active;
		tick_stopped = ts->tick_stopped;

		if (ts->idle_active \|\| ts->tick_stopped)
		if (idle_active \|\| tick_stopped)
		now = ktime_get();

		if (ts->idle_active)
		if (idle_active)
		tick_nohz_stop_idle(ts, now);

		if (ts->tick_stopped)
		if (tick_stopped)
		__tick_nohz_idle_restart_tick(ts, now);

		local_irq_enable();

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