[Intel-gfx] [PATCH] lib/igt_aux: make igt_wait_for_pm_status() resist the signal helper

[Daniel Vetter]

On Tue, Oct 14, 2014 at 04:12:22PM -0300, Paulo Zanoni wrote:
> From: Paulo Zanoni <paulo.r.zanoni at intel.com>
> 
> If the signal helper is active, the usleep() calls return earlier, and
> we may end up returning false way before the 10s timeout, failing the
> subtests. This currently happens on the kms_flip RPM interruptible
> subtests.
> 
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=78893
> Signed-off-by: Paulo Zanoni <paulo.r.zanoni at intel.com>
> ---
>  lib/igt_aux.c | 17 ++++++++++++-----
>  1 file changed, 12 insertions(+), 5 deletions(-)
> 
> diff --git a/lib/igt_aux.c b/lib/igt_aux.c
> index b32297e..01654f0 100644
> --- a/lib/igt_aux.c
> +++ b/lib/igt_aux.c
> @@ -42,6 +42,7 @@
>  #include <stdlib.h>
>  #include <unistd.h>
>  #include <sys/wait.h>
> +#include <sys/time.h>
>  #include <sys/types.h>
>  #include <sys/syscall.h>
>  #include <sys/utsname.h>
> @@ -502,21 +503,27 @@ enum igt_runtime_pm_status igt_get_runtime_pm_status(void)
>   * Waits until for the driver to switch to into the desired runtime PM status,
>   * with a 10 second timeout.
>   *
> + * Some subtests call this function while the signal helper is active, so we
> + * can't assume each usleep() call will sleep for 100ms.
> + *
>   * Returns:
>   * True if the desired runtime PM status was attained, false if the operation
>   * timed out.
>   */
>  bool igt_wait_for_pm_status(enum igt_runtime_pm_status status)
>  {
> -	int i;
> -	int hundred_ms = 100 * 1000, ten_s = 10 * 1000 * 1000;
> +	struct timeval start, end, diff;
>  
> -	for (i = 0; i < ten_s; i += hundred_ms) {
> +	igt_assert(gettimeofday(&start, NULL) == 0);
> +	do {
>  		if (igt_get_runtime_pm_status() == status)
>  			return true;
>  
> -		usleep(hundred_ms);
> -	}
> +		usleep(100 * 1000);
> +
> +		igt_assert(gettimeofday(&end, NULL) == 0);
> +		timersub(&end, &start, &diff);

Should we have a generic igt_usleep helper which is signal-robust? Just a
quick idea since there's probably more like these.
-Daniel

> +	} while (diff.tv_sec < 10);
>  
>  	return false;
>  }
> -- 
> 1.9.1
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch