[PATCH] drm/amdgpu:fix race condition

[Christian König]

Am 10.04.2017 um 09:39 schrieb Monk Liu:
> sequence is protected by spinlock so don't access sequence
> in paramter seq when invoking this function.
>
> ~0 means to get the latest sequence number and 0 means none to
> get.

Well you are still not using ~0ull as I said. Using ~0 here will cause 
0xffffffff to be used instead of 0xffffffffffffffff.

Additional to that please add a define into amdgpu_drm.h to document 
this interface change.

Christian.

>
> Change-Id: Ib7a03f3cf5594deeb4ad333cc59b47a6bddfd1ad
> Signed-off-by: Monk Liu <Monk.Liu at amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c | 3 +++
>   1 file changed, 3 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
> index 6d86eae..c24bb90 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
> @@ -277,6 +277,9 @@ struct fence *amdgpu_ctx_get_fence(struct amdgpu_ctx *ctx,
>   
>   	spin_lock(&ctx->ring_lock);
>   
> +	if (seq == ~0)
> +		seq = ctx->rings[ring->idx].sequence - 1;
> +
>   	if (seq >= cring->sequence) {
>   		spin_unlock(&ctx->ring_lock);
>   		return ERR_PTR(-EINVAL);