Re: [igt-dev] [PATCH igt] lib: Use C99 initialisers to clear context parameters

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 07/03/2018 12:17, Chris Wilson wrote:
> valgrind complains we feed uninitialised stack into the CONTEXT_SETPARAM
> ioctl. It is unused by the kernel, but valgrind doesn't know that and
> it's easy enough to clear the struct to prevent the warning.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>   lib/igt_gt.c | 29 ++++++++++++-----------------
>   1 file changed, 12 insertions(+), 17 deletions(-)
> 
> diff --git a/lib/igt_gt.c b/lib/igt_gt.c
> index 799ca1ae..168c5a07 100644
> --- a/lib/igt_gt.c
> +++ b/lib/igt_gt.c
> @@ -126,11 +126,10 @@ void igt_require_hang_ring(int fd, int ring)
>   
>   static unsigned context_get_ban(int fd, unsigned ctx)
>   {
> -	struct drm_i915_gem_context_param param;
> -
> -	param.param = I915_CONTEXT_PARAM_BANNABLE;
> -	param.value = 0;
> -	param.size = 0;
> +	struct drm_i915_gem_context_param param = {
> +		.ctx_id = ctx,

Where was this assignment before? Was it all broken as well as upsetting 
Valgrind?

Regards,

Tvrtko

> +		.param = I915_CONTEXT_PARAM_BANNABLE,
> +	};
>   
>   	if (__gem_context_get_param(fd, &param) == -EINVAL) {
>   		igt_assert(param.value == 0);
> @@ -143,13 +142,11 @@ static unsigned context_get_ban(int fd, unsigned ctx)
>   
>   static void context_set_ban(int fd, unsigned ctx, unsigned ban)
>   {
> -	struct drm_i915_gem_context_param param;
> -
> -	memset(&param, 0, sizeof(param));
> -	param.ctx_id = ctx;
> -	param.value = ban;
> -	param.size = 0;
> -	param.param = I915_CONTEXT_PARAM_BANNABLE;
> +	struct drm_i915_gem_context_param param = {
> +		.ctx_id = ctx,
> +		.param = I915_CONTEXT_PARAM_BANNABLE,
> +		.value = ban,
> +	};
>   
>   	if(__gem_context_set_param(fd, &param) == -EINVAL) {
>   		igt_assert(param.value == ban);
> @@ -160,7 +157,9 @@ static void context_set_ban(int fd, unsigned ctx, unsigned ban)
>   
>   igt_hang_t igt_allow_hang(int fd, unsigned ctx, unsigned flags)
>   {
> -	struct drm_i915_gem_context_param param;
> +	struct drm_i915_gem_context_param param = {
> +		.ctx_id = ctx,
> +	};
>   	unsigned ban;
>   
>   	igt_assert(igt_sysfs_set_parameter
> @@ -172,9 +171,6 @@ igt_hang_t igt_allow_hang(int fd, unsigned ctx, unsigned flags)
>   	if (!igt_check_boolean_env_var("IGT_HANG_WITHOUT_RESET", false))
>   		igt_require(has_gpu_reset(fd));
>   
> -	param.ctx_id = ctx;
> -	param.size = 0;
> -
>   	if ((flags & HANG_ALLOW_CAPTURE) == 0) {
>   		param.param = I915_CONTEXT_PARAM_NO_ERROR_CAPTURE;
>   		param.value = 1;
> @@ -194,7 +190,6 @@ igt_hang_t igt_allow_hang(int fd, unsigned ctx, unsigned flags)
>   
>   void igt_disallow_hang(int fd, igt_hang_t arg)
>   {
> -
>   	context_set_ban(fd, arg.ctx, arg.ban);
>   
>   	if ((arg.flags & HANG_ALLOW_CAPTURE) == 0) {
> 
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