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SubjectRe: [RFC 09/17] drm/amdgpu: use dma-fence annotations in cs_submit()
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Am 12.05.20 um 10:59 schrieb Daniel Vetter:
> This is a bit tricky, since ->notifier_lock is held while calling
> dma_fence_wait we must ensure that also the read side (i.e.
> dma_fence_begin_signalling) is on the same side. If we mix this up
> lockdep complaints, and that's again why we want to have these
> annotations.
>
> A nice side effect of this is that because of the fs_reclaim priming
> for dma_fence_enable lockdep now automatically checks for us that
> nothing in here allocates memory, without even running any userptr
> workloads.
>
> Cc: linux-media@vger.kernel.org
> Cc: linaro-mm-sig@lists.linaro.org
> Cc: linux-rdma@vger.kernel.org
> Cc: amd-gfx@lists.freedesktop.org
> Cc: intel-gfx@lists.freedesktop.org
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Cc: Christian König <christian.koenig@amd.com>
> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> ---
> drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> index 7653f62b1b2d..6db3f3c629b0 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> @@ -1213,6 +1213,7 @@ static int amdgpu_cs_submit(struct amdgpu_cs_parser *p,
> struct amdgpu_job *job;
> uint64_t seq;
> int r;
> + bool fence_cookie;
>
> job = p->job;
> p->job = NULL;
> @@ -1227,6 +1228,8 @@ static int amdgpu_cs_submit(struct amdgpu_cs_parser *p,
> */
> mutex_lock(&p->adev->notifier_lock);
>
> + fence_cookie = dma_fence_begin_signalling();
> +
> /* If userptr are invalidated after amdgpu_cs_parser_bos(), return
> * -EAGAIN, drmIoctl in libdrm will restart the amdgpu_cs_ioctl.
> */
> @@ -1264,12 +1267,14 @@ static int amdgpu_cs_submit(struct amdgpu_cs_parser *p,
> amdgpu_vm_move_to_lru_tail(p->adev, &fpriv->vm);
>
> ttm_eu_fence_buffer_objects(&p->ticket, &p->validated, p->fence);
> + dma_fence_end_signalling(fence_cookie);

Mhm, this could come earlier in theory. E.g. after pushing the job to
the scheduler.

Christian.

> mutex_unlock(&p->adev->notifier_lock);
>
> return 0;
>
> error_abort:
> drm_sched_job_cleanup(&job->base);
> + dma_fence_end_signalling(fence_cookie);
> mutex_unlock(&p->adev->notifier_lock);
>
> error_unlock:

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