[PATCH i-g-t] tests/intel/xe_oa: Look at errno only when system calls fail

[Kamil Konieczny]

Hi Ashutosh,
On 2025-07-08 at 08:16:59 -0700, Ashutosh Dixit wrote:
> errno is set only when system calls fail, so it is incorrect to look at
> errno when system calls succeed.
> 

LGTM,
Reviewed-by: Kamil Konieczny <kamil.konieczny at linux.intel.com>

> Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/5339
> Signed-off-by: Ashutosh Dixit <ashutosh.dixit at intel.com>
> ---
>  tests/intel/xe_oa.c | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/tests/intel/xe_oa.c b/tests/intel/xe_oa.c
> index cb59918ef9..724fea73f0 100644
> --- a/tests/intel/xe_oa.c
> +++ b/tests/intel/xe_oa.c
> @@ -1431,7 +1431,7 @@ read_2_oa_reports(int format_id,
>  
>  		while ((ret = read(stream_fd, buf + len, buf_size)) < 0 && errno == EINTR)
>  			;
> -		if (errno == EIO) {
> +		if (ret < 0 && errno == EIO) {
>  			oa_status = get_stream_status(stream_fd);
>  			continue;
>  		}
> @@ -1869,7 +1869,7 @@ static void test_oa_exponents(const struct drm_xe_engine_class_instance *hwe)
>  
>  			while ((ret = read(stream_fd, buf, buf_size)) < 0 && errno == EINTR)
>  				;
> -			if (errno == EIO) {
> +			if (ret < 0 && errno == EIO) {
>  				oa_status = get_stream_status(stream_fd);
>  				continue;
>  			}
> @@ -2532,7 +2532,6 @@ test_buffer_fill(const struct drm_xe_engine_class_instance *hwe)
>  
>  	do_ioctl(stream_fd, DRM_XE_OBSERVATION_IOCTL_ENABLE, 0);
>  
> -	errno = 0;
>  	/* Read 0 bytes repeatedly until you see an EIO */
>  	while (-1 == read(stream_fd, buf, 0)) {
>  		if (errno == EIO) {
> @@ -2607,7 +2606,7 @@ test_non_zero_reason(const struct drm_xe_engine_class_instance *hwe, size_t oa_b
>  	       ((len = read(stream_fd, &buf[total_len], buf_size - total_len)) > 0 ||
>  		(len == -1 && (errno == EINTR || errno == EIO)))) {
>  		/* Assert only for default OA buffer size */
> -		if (errno == EIO && !oa_buffer_size) {
> +		if (len < 0 && errno == EIO && !oa_buffer_size) {
>  			oa_status = get_stream_status(stream_fd);
>  			igt_assert(!(oa_status & DRM_XE_OASTATUS_BUFFER_OVERFLOW));
>  		}
> -- 
> 2.48.1
>