From 1f70999f9052f5a1b0ce1a55aff3808f2ec9fe42 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Mon, 27 Jan 2014 22:43:07 +0000 Subject: [PATCH] drm/i915: Prevent recursion by retiring requests when the ring is full MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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: Chris Wilson Reviewed-by: Ville Syrjälä Signed-off-by: Daniel Vetter --- drivers/gpu/drm/i915/intel_ringbuffer.c | 25 +++++-------------------- 1 file changed, 5 insertions(+), 20 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c index d897a19f887f..ba686d75ff32 100644 --- a/drivers/gpu/drm/i915/intel_ringbuffer.c +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c @@ -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;