[Intel-gfx] [RFC 09/17] drm/amdgpu: use dma-fence annotations in cs_submit()

[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 at vger.kernel.org
Cc: linaro-mm-sig at lists.linaro.org
Cc: linux-rdma at vger.kernel.org
Cc: amd-gfx at lists.freedesktop.org
Cc: intel-gfx at lists.freedesktop.org
Cc: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Cc: Christian König <christian.koenig at amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter at 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);
 	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:
-- 
2.26.2