4.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: Chris Wilson chris@chris-wilson.co.uk
commit 117172c8f9d40ba1de8cb35c6e614422faa03330 upstream.
When a request is preempted, it is unsubmitted from the HW queue and removed from the active list of breadcrumbs. In the process, this however triggers the signaler and it may see the clear rbtree with the old, and still valid, seqno, or it may match the cleared seqno with the now zero rq->global_seqno. This confuses the signaler into action and signaling the fence.
Fixes: d6a2289d9d6b ("drm/i915: Remove the preempted request from the execution queue") Signed-off-by: Chris Wilson chris@chris-wilson.co.uk Cc: Tvrtko Ursulin tvrtko.ursulin@linux.intel.com Cc: Joonas Lahtinen joonas.lahtinen@linux.intel.com Cc: stable@vger.kernel.org # v4.12+ Reviewed-by: Tvrtko Ursulin tvrtko.ursulin@intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20180206094633.30181-1-chris@c... (cherry picked from commit fd10e2ce9905030d922e179a8047a4d50daffd8e) Signed-off-by: Rodrigo Vivi rodrigo.vivi@intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20180213090154.17373-1-chris@c... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/gpu/drm/i915/intel_breadcrumbs.c | 29 ++++++++++------------------- 1 file changed, 10 insertions(+), 19 deletions(-)
--- a/drivers/gpu/drm/i915/intel_breadcrumbs.c +++ b/drivers/gpu/drm/i915/intel_breadcrumbs.c @@ -552,29 +552,16 @@ void intel_engine_remove_wait(struct int spin_unlock_irq(&b->rb_lock); }
-static bool signal_valid(const struct drm_i915_gem_request *request) -{ - return intel_wait_check_request(&request->signaling.wait, request); -} - static bool signal_complete(const struct drm_i915_gem_request *request) { if (!request) return false;
- /* If another process served as the bottom-half it may have already - * signalled that this wait is already completed. - */ - if (intel_wait_complete(&request->signaling.wait)) - return signal_valid(request); - - /* Carefully check if the request is complete, giving time for the + /* + * Carefully check if the request is complete, giving time for the * seqno to be visible or if the GPU hung. */ - if (__i915_request_irq_complete(request)) - return true; - - return false; + return __i915_request_irq_complete(request); }
static struct drm_i915_gem_request *to_signaler(struct rb_node *rb) @@ -617,9 +604,13 @@ static int intel_breadcrumbs_signaler(vo request = i915_gem_request_get_rcu(request); rcu_read_unlock(); if (signal_complete(request)) { - local_bh_disable(); - dma_fence_signal(&request->fence); - local_bh_enable(); /* kick start the tasklets */ + if (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, + &request->fence.flags)) { + local_bh_disable(); + dma_fence_signal(&request->fence); + GEM_BUG_ON(!i915_gem_request_completed(request)); + local_bh_enable(); /* kick start the tasklets */ + }
spin_lock_irq(&b->rb_lock);