Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 1f70999f authored by Chris Wilson's avatar Chris Wilson Committed by Daniel Vetter
Browse files

drm/i915: Prevent recursion by retiring requests when the ring is full 



As the VM do not track activity of objects and instead use a large
hammer to forcibly idle and evict all of their associated objects when
one is released, it is possible for that to cause a recursion when we
need to wait for free space on a ring and call retire requests.
(intel_ring_begin -> intel_ring_wait_request ->
i915_gem_retire_requests_ring -> i915_gem_context_free ->
i915_gem_evict_vm -> i915_gpu_idle -> intel_ring_begin etc)

In order to remove the requirement for calling retire-requests from
intel_ring_wait_request, we have to inline a couple of steps from
retiring requests, notably we have to record the position of the request
we wait for and use that to update the available ring space.

Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: default avatarVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
parent 011cf577

drivers/gpu/drm/i915/intel_ringbuffer.c

+5 −20
Original line number Diff line number Diff line
@@ -1430,28 +1430,16 @@ void intel_cleanup_ring_buffer(struct intel_ring_buffer *ring) 
	cleanup_status_page(ring);

}



static int intel_ring_wait_seqno(struct intel_ring_buffer *ring, u32 seqno)

{

	int ret;



	ret = i915_wait_seqno(ring, seqno);

	if (!ret)

		i915_gem_retire_requests_ring(ring);



	return ret;

}



static int intel_ring_wait_request(struct intel_ring_buffer *ring, int n)

{

	struct drm_i915_gem_request *request;

	u32 seqno = 0;

	u32 seqno = 0, tail;

	int ret;



	i915_gem_retire_requests_ring(ring);



	if (ring->last_retired_head != -1) {

		ring->head = ring->last_retired_head;

		ring->last_retired_head = -1;



		ring->space = ring_space(ring);

		if (ring->space >= n)

			return 0;
@@ -1468,6 +1456,7 @@ static int intel_ring_wait_request(struct intel_ring_buffer *ring, int n) 
			space += ring->size;

		if (space >= n) {

			seqno = request->seqno;

			tail = request->tail;

			break;

		}
@@ -1482,15 +1471,11 @@ static int intel_ring_wait_request(struct intel_ring_buffer *ring, int n) 
	if (seqno == 0)

		return -ENOSPC;



	ret = intel_ring_wait_seqno(ring, seqno);

	ret = i915_wait_seqno(ring, seqno);

	if (ret)

		return ret;



	if (WARN_ON(ring->last_retired_head == -1))

		return -ENOSPC;



	ring->head = ring->last_retired_head;

	ring->last_retired_head = -1;

	ring->head = tail;

	ring->space = ring_space(ring);

	if (WARN_ON(ring->space < n))

		return -ENOSPC;