[Intel-gfx] [PATCH 5/5] drm/i915/gem: Silence sparse for RCU protection inside the constructor

[Tvrtko Ursulin]

On 14/11/2019 22:57, Chris Wilson wrote:
> Inside the constructor, while cloning, we need to replace the
> dst->engines. Having forgotten that dst->engines is marked as RCU
> protected, we need to add the appropriate annotations to make sparse
> happy.
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> ---
>   drivers/gpu/drm/i915/gem/i915_gem_context.c | 6 ++++--
>   1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c
> index 1284f47303fa..6f1e6181f67a 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
> @@ -2009,7 +2009,8 @@ static int clone_engines(struct i915_gem_context *dst,
>   	user_engines = i915_gem_context_user_engines(src);
>   	i915_gem_context_unlock_engines(src);
>   
> -	free_engines(dst->engines);
> +	/* Serialised by constructor */
> +	free_engines(__context_engines_static(dst));
>   	RCU_INIT_POINTER(dst->engines, clone);
>   	if (user_engines)
>   		i915_gem_context_set_user_engines(dst);
> @@ -2044,7 +2045,8 @@ static int clone_sseu(struct i915_gem_context *dst,
>   	unsigned long n;
>   	int err;
>   
> -	clone = dst->engines; /* no locking required; sole access */
> +	/* no locking required; sole access under constructor*/
> +	clone = __context_engines_static(dst);
>   	if (e->num_engines != clone->num_engines) {
>   		err = -EINVAL;
>   		goto unlock;
> 

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

Regards,

Tvrtko