drm/i915/gt: Decouple completed requests on unwind

Since the introduction of preempt-to-busy, requests can complete in the
background, even while they are not on the engine->active.requests list.
As such, the engine->active.request list itself is not in strict
retirement order, and we have to scan the entire list while unwinding to
not miss any. However, if the request is completed we currently leave it
on the list [until retirement], but we could just as simply remove it
and stop treating it as active. We would only have to then traverse it
once while unwinding in quick succession.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201126140407.31952-1-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
index 30aa59fb72713f868363ad927e68b38ba9c4265a..cf11cbac241bb06c6a53c3b302cbc6cd70cdc9f1 100644 (file)
--- a/drivers/gpu/drm/i915/gt/intel_lrc.c
+++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
@@ -1116,8 +1116,10 @@ __unwind_incomplete_requests(struct intel_engine_cs *engine)
        list_for_each_entry_safe_reverse(rq, rn,
                                         &engine->active.requests,
                                         sched.link) {
-               if (i915_request_completed(rq))
-                       continue; /* XXX */
+               if (i915_request_completed(rq)) {
+                       list_del_init(&rq->sched.link);
+                       continue;
+               }
 
                __i915_request_unsubmit(rq);
 

diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
index 8d7d29c9e375d65132eb9acb236f0a8e18628a47..a9db1376b996c4a536fe827c806d0a9fc5e7a4fd 100644 (file)
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -321,7 +321,8 @@ bool i915_request_retire(struct i915_request *rq)
         * after removing the breadcrumb and signaling it, so that we do not
         * inadvertently attach the breadcrumb to a completed request.
         */
-       remove_from_engine(rq);
+       if (!list_empty(&rq->sched.link))
+               remove_from_engine(rq);
        GEM_BUG_ON(!llist_empty(&rq->execute_cb));
 
        __list_del_entry(&rq->link); /* poison neither prev/next (RCU walks) */