>That is unnecessary the "if (seq + amdgpu_sched_jobs < cring->sequence) {" will catch this case.
But what if user land pass in seq 0 on purpose , but the latest cring->sequence value is only 3 ?
Without this "if (seq == 0)" the logic seems goes to a wrong direction
BR Monk
-----é?®ä»¶å??件-----
å??件人: Christian König [mailto:deathsimple at vodafone.de]
å??é??æ?¶é?´: Monday, April 10, 2017 3:22 PM
�件人: Liu, Monk <Monk.Liu at amd.com>; amd-gfx at lists.freedesktop.org
主�: Re: [PATCH] drm/amdgpu:fix race condition
Am 10.04.2017 um 09:18 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.
>
> Change-Id: Ib7a03f3cf5594deeb4ad333cc59b47a6bddfd1ad
> Signed-off-by: Monk Liu <Monk.Liu at amd.com>
> ---
> drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
> index 6d86eae..71d5f25 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
> @@ -277,6 +277,13 @@ struct fence *amdgpu_ctx_get_fence(struct
> amdgpu_ctx *ctx,
>
> spin_lock(&ctx->ring_lock);
>
> + if (seq == ~0) {
That must be ~0ull, otherwise you would be checking a 32bit value here.
Additional to that please define something in amdgpu_drm.h for that value.
> + seq = ctx->rings[ring->idx].sequence - 1;
> + } else if(seq == 0) {
> + spin_unlock(&ctx->ring_lock);
> + return NULL;
> + }
> +
That is unnecessary the "if (seq + amdgpu_sched_jobs < cring->sequence) {" will catch this case.
Regards,
Christian.
> if (seq >= cring->sequence) {
> spin_unlock(&ctx->ring_lock);
> return ERR_PTR(-EINVAL);
