Re: [PATCH] selftests: timers: set-timer-lat: Fix hang when testing unsupported alarms

From: Shuah Khan
Date: Fri Sep 22 2017 - 10:41:44 EST


Hi John/Greg,

On 09/21/2017 01:45 PM, Shuah Khan wrote:
> When timer_create() fails on a bootime or realtime clock, setup_timer()
> returns 0 as if timer has been set. Callers wait forever for the timer
> to expire.
>
> This hang is seen on a system that doesn't have support for:
>
> CLOCK_REALTIME_ALARM ABSTIME missing CAP_WAKE_ALARM? : [UNSUPPORTED]
>
> Test hangs waiting for a timer that hasn't been set to expire.
>
> Signed-off-by: Shuah Khan <shuahkh@xxxxxxxxxxxxxxx>
> ---
> tools/testing/selftests/timers/set-timer-lat.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/timers/set-timer-lat.c b/tools/testing/selftests/timers/set-timer-lat.c
> index 9c92b7bd5641..ab2fe225e051 100644
> --- a/tools/testing/selftests/timers/set-timer-lat.c
> +++ b/tools/testing/selftests/timers/set-timer-lat.c
> @@ -143,7 +143,8 @@ int setup_timer(int clock_id, int flags, int interval, timer_t *tm1)
> printf("%-22s %s missing CAP_WAKE_ALARM? : [UNSUPPORTED]\n",
> clockstring(clock_id),
> flags ? "ABSTIME":"RELTIME");
> - return 0;
> + /* Indicate timer isn't set, so caller doesn't wait */
> + return 1;
> }
> printf("%s - timer_create() failed\n", clockstring(clock_id));
> return -1;
>

I assume you are good with this fix. I plan to apply it to linux-kselftest fixes
today. Please let me know if you have any objections.

thanks,
-- Shuah