[igt-dev] [PATCH i-g-t] i915/hangman: Read a dummy byte to check sysfs existence

[Tvrtko Ursulin]

On 11/01/2019 10:35, Chris Wilson wrote:
> sysfs doesn't give the driver an open() callback, so we can only report
> the unavailability of HW on the first read; so check read() after checking
> open().
> 
> Fixes: 93f0ad4b835e ("i915/hangman: Skip if disabled by the kernel")
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> ---
>   tests/i915/hangman.c | 8 +++++++-
>   1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/tests/i915/hangman.c b/tests/i915/hangman.c
> index ffbd0b057..5f63bfc4b 100644
> --- a/tests/i915/hangman.c
> +++ b/tests/i915/hangman.c
> @@ -45,14 +45,20 @@ static int sysfs = -1;
>   
>   static bool has_error_state(int dir)
>   {
> +	bool result;
>   	int fd;
>   
>   	fd = openat(dir, "error", O_RDONLY);
>   	if (fd < 0)
>   		return false;
>   
> +	if (read(fd, &result, sizeof(result)) < 0)
> +		result = false;
> +	else
> +		result = true;
> +
>   	close(fd);
> -	return true;
> +	return result;
>   }
>   
>   static void assert_entry(const char *s, bool expect)
> 

Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>

Regards,

Tvrtko