Re: [PATCH] drm/amdgpu: allocate large structures dynamically

[Christian KÃnig]

Am 06.05.20 um 21:01 schrieb Joe Perches:
> On Tue, 2020-05-05 at 16:01 +0200, Arnd Bergmann wrote:
> > After the structure was padded to 1024 bytes, it is no longer
> > suitable for being a local variable, as the function surpasses
> > the warning limit for 32-bit architectures:
> >
> > drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c:587:5: error: stack frame size of 1072 bytes in function 'amdgpu_ras_feature_enable' [-Werror,-Wframe-larger-than=]
> > int amdgpu_ras_feature_enable(struct amdgpu_device *adev,
> >      ^
> >
> > Use kzalloc() instead to get it from the heap.
> []
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c
> []
> > @@ -588,19 +588,23 @@ int amdgpu_ras_feature_enable(struct amdgpu_device *adev,
> >   		struct ras_common_if *head, bool enable)
> >   {
> >   	struct amdgpu_ras *con = amdgpu_ras_get_context(adev);
> > -	union ta_ras_cmd_input info;
> > +	union ta_ras_cmd_input *info;
> >   	int ret;
> >   
> >   	if (!con)
> >   		return -EINVAL;
> >   
> > +        info = kzalloc(sizeof(union ta_ras_cmd_input), GFP_KERNEL);
> Spaces were used for indentation here not a tab.
> It might be useful to run your proposed patches through checkpatch
>
> Is this an actual bug fix as the previous use didn't
> zero unused info members?
>
> > +	if (!info)
> > +		return -ENOMEM;
> > +
> >   	if (!enable) {
> > -		info.disable_features = (struct ta_ras_disable_features_input) {
> > +		info->disable_features = (struct ta_ras_disable_features_input) {
> >   			.block_id =  amdgpu_ras_block_to_ta(head->block),
> >   			.error_type = amdgpu_ras_error_to_ta(head->type),
> >   		};
> >   	} else {
> > -		info.enable_features = (struct ta_ras_enable_features_input) {
> > +		info->enable_features = (struct ta_ras_enable_features_input) {
> >   			.block_id =  amdgpu_ras_block_to_ta(head->block),
> >   			.error_type = amdgpu_ras_error_to_ta(head->type),
> >   		};
> > @@ -609,26 +613,33 @@ int amdgpu_ras_feature_enable(struct amdgpu_device *adev,
> >   	/* Do not enable if it is not allowed. */
> >   	WARN_ON(enable && !amdgpu_ras_is_feature_allowed(adev, head));
> >   	/* Are we alerady in that state we are going to set? */
> > -	if (!(!!enable ^ !!amdgpu_ras_is_feature_enabled(adev, head)))
> > -		return 0;
> > +	if (!(!!enable ^ !!amdgpu_ras_is_feature_enabled(adev, head))) {
> And trivia:
>
> The !! uses with bool seem unnecessary and it's probably better
> to make amdgpu_ras_is_feature_enabled to return bool.
>
> Maybe something like:
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c | 12 ++++++------
>   1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c
> index 538895cfd862..05c4eaf0ddfa 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c
> @@ -526,16 +526,16 @@ void amdgpu_ras_parse_status_code(struct amdgpu_device* adev,
>   }
>   
>   /* feature ctl begin */
> -static int amdgpu_ras_is_feature_allowed(struct amdgpu_device *adev,
> -		struct ras_common_if *head)
> +static bool amdgpu_ras_is_feature_allowed(struct amdgpu_device *adev,
> +					  struct ras_common_if *head)
>   {
>   	struct amdgpu_ras *con = amdgpu_ras_get_context(adev);
>   
>   	return con->hw_supported & BIT(head->block);
>   }
>   
> -static int amdgpu_ras_is_feature_enabled(struct amdgpu_device *adev,
> -		struct ras_common_if *head)
> +static bool amdgpu_ras_is_feature_enabled(struct amdgpu_device *adev,
> +					  struct ras_common_if *head)
>   {
>   	struct amdgpu_ras *con = amdgpu_ras_get_context(adev);
>   
> @@ -560,7 +560,7 @@ static int __amdgpu_ras_feature_enable(struct amdgpu_device *adev,
>   	 */
>   	if (!amdgpu_ras_is_feature_allowed(adev, head))
>   		return 0;
> -	if (!(!!enable ^ !!amdgpu_ras_is_feature_enabled(adev, head)))
> +	if (!(enable ^ amdgpu_ras_is_feature_enabled(adev, head)))

And while we are at improving coding style I think that writing this as 
"if (enabled == amdgpu_ras_is_feature_enabled(adev, head))" would be 
much more readable.

Christian.

>   		return 0;
>   
>   	if (enable) {
> @@ -609,7 +609,7 @@ int amdgpu_ras_feature_enable(struct amdgpu_device *adev,
>   	/* Do not enable if it is not allowed. */
>   	WARN_ON(enable && !amdgpu_ras_is_feature_allowed(adev, head));
>   	/* Are we alerady in that state we are going to set? */
> -	if (!(!!enable ^ !!amdgpu_ras_is_feature_enabled(adev, head)))
> +	if (!(enable ^ amdgpu_ras_is_feature_enabled(adev, head)))
>   		return 0;
>   
>   	if (!amdgpu_ras_intr_triggered()) {
>
>
>
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