posix-timers: give lazy compilers some help optimizing code away

Nicolas Pitre · torvalds · commit b6f8a92c9ca8 · 2016-12-14T16:04:08.000-08:00
The OpenRISC compiler (so far) fails to optimize away a large portion of
code containing a reference to posix_timer_event in alarmtimer.c when
CONFIG_POSIX_TIMERS is unset.  Let's give it a direct clue to let the
build succeed.

This fixes
[linux-next:master 6682/7183] alarmtimer.c:undefined reference to `posix_timer_event'
reported by kbuild test robot.

Signed-off-by: Nicolas Pitre &lt;nico@linaro.org&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Josh Triplett &lt;josh@joshtriplett.org&gt;

Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
@@ -516,7 +516,8 @@ static enum alarmtimer_restart alarm_handle_timer(struct alarm *alarm,
 
 	spin_lock_irqsave(&ptr->it_lock, flags);
 	if ((ptr->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE) {
-		if (posix_timer_event(ptr, 0) != 0)
+		if (IS_ENABLED(CONFIG_POSIX_TIMERS) &&
+		    posix_timer_event(ptr, 0) != 0)
 			ptr->it_overrun++;
 	}
 

Original file line number	Diff line number	Diff line change
`@@ -516,7 +516,8 @@ static enum alarmtimer_restart alarm_handle_timer(struct alarm *alarm,`
`516`	`516`
`517`	`517`	`spin_lock_irqsave(&ptr->it_lock, flags);`
`518`	`518`	`if ((ptr->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE) {`
`519`		`- if (posix_timer_event(ptr, 0) != 0)`
	`519`	`+ if (IS_ENABLED(CONFIG_POSIX_TIMERS) &&`
	`520`	`+ posix_timer_event(ptr, 0) != 0)`
`520`	`521`	`ptr->it_overrun++;`
`521`	`522`	`}`
`522`	`523`