drm/i915/breadcrumbs: Ignore unsubmitted signalers

Web:        https://git.kernel.org/torvalds/c/117172c8f9d40ba1de8cb35c6e614422faa03330
Commit:     117172c8f9d40ba1de8cb35c6e614422faa03330
Parent:     7292b9e6586534fb43e4316ad8b508bf3d1212f7
Refname:    refs/heads/master
Author:     Chris Wilson <[email protected]>
AuthorDate: Tue Feb 13 09:01:54 2018 +0000
Committer:  Rodrigo Vivi <[email protected]>
CommitDate: Tue Feb 13 16:55:45 2018 -0800

    drm/i915/breadcrumbs: Ignore unsubmitted signalers
    
    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 <[email protected]>
    Cc: Tvrtko Ursulin <[email protected]>
    Cc: Joonas Lahtinen <[email protected]>
    Cc: <[email protected]> # v4.12+
    Reviewed-by: Tvrtko Ursulin <[email protected]>
    Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
    (cherry picked from commit fd10e2ce9905030d922e179a8047a4d50daffd8e)
    Signed-off-by: Rodrigo Vivi <[email protected]>
    Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
---
 drivers/gpu/drm/i915/intel_breadcrumbs.c | 29 ++++++++++-------------------
 1 file changed, 10 insertions(+), 19 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_breadcrumbs.c b/drivers/gpu/drm/i915/intel_breadcrumbs.c
index bd40fea16b4f..f54ddda9fdad 100644
--- a/drivers/gpu/drm/i915/intel_breadcrumbs.c
+++ b/drivers/gpu/drm/i915/intel_breadcrumbs.c
@@ -594,29 +594,16 @@ void intel_engine_remove_wait(struct intel_engine_cs *engine,
 	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;