drm/i915/execlists: Mark up priority boost on preemption

Record the priority boost we giving to the preempted client or else we
may end up in a situation where the priority queue no longer matches the
request priority order and so we can end up in an infinite loop of
preempting the same pair of requests.

Fixes: e9eaf82d97a2 ("drm/i915: Priority boost for waiting clients")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190123135155.21562-1-chris@chris-wilson.co.uk
(cherry picked from commit 6e062b60b0b1bd82cac475e63cdb8c451647182b)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 4796f40..eab9341 100644 (file)
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -303,6 +303,7 @@ static void __unwind_incomplete_requests(struct intel_engine_cs *engine)
         */
        if (!(prio & I915_PRIORITY_NEWCLIENT)) {
                prio |= I915_PRIORITY_NEWCLIENT;
+               active->sched.attr.priority = prio;
                list_move_tail(&active->sched.link,
                               i915_sched_lookup_priolist(engine, prio));
        }
@@ -645,6 +646,9 @@ static void execlists_dequeue(struct intel_engine_cs *engine)
                int i;
 
                priolist_for_each_request_consume(rq, rn, p, i) {
+                       GEM_BUG_ON(last &&
+                                  need_preempt(engine, last, rq_prio(rq)));
+
                        /*
                         * Can we combine this request with the current port?
                         * It has to be the same context/ringbuffer and not