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>

diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 956831c..e35a6fc 100644 (file)
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -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();