drm/i915: Cancel all ready but queued requests when wedging

When wedging the hw, we want to mark all in-flight requests as -EIO.
This is made slightly more complex by execlists who store the ready but
not yet submitted-to-hw requests on a private queue (an rbtree
priolist). Call into execlists to cancel not only the ELSP tracking for
the submitted requests, but also the queue of unsubmitted requests.

v2: Move the majority of engine_set_wedged to the backends (both legacy
ringbuffer and execlists handling their own lists).

Reported-by: Michał Winiarski <michal.winiarski@intel.com>
Testcase: igt/gem_eio/in-flight-contexts
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Michał Winiarski <michal.winiarski@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170915173100.26470-1-chris@chris-wilson.co.uk
Reviewed-by: Michał Winiarski <michal.winiarski@intel.com>
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index f445587..b0bbf87 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -3022,9 +3022,6 @@ static void nop_submit_request(struct drm_i915_gem_request *request)
 
 static void engine_set_wedged(struct intel_engine_cs *engine)
 {
-	struct drm_i915_gem_request *request;
-	unsigned long flags;
-
 	/* We need to be sure that no thread is running the old callback as
 	 * we install the nop handler (otherwise we would submit a request
 	 * to hardware that will never complete). In order to prevent this
@@ -3034,40 +3031,7 @@ static void engine_set_wedged(struct intel_engine_cs *engine)
 	engine->submit_request = nop_submit_request;
 
 	/* Mark all executing requests as skipped */
-	spin_lock_irqsave(&engine->timeline->lock, flags);
-	list_for_each_entry(request, &engine->timeline->requests, link)
-		if (!i915_gem_request_completed(request))
-			dma_fence_set_error(&request->fence, -EIO);
-	spin_unlock_irqrestore(&engine->timeline->lock, flags);
-
-	/*
-	 * Clear the execlists queue up before freeing the requests, as those
-	 * are the ones that keep the context and ringbuffer backing objects
-	 * pinned in place.
-	 */
-
-	if (i915.enable_execlists) {
-		struct execlist_port *port = engine->execlist_port;
-		unsigned long flags;
-		unsigned int n;
-
-		spin_lock_irqsave(&engine->timeline->lock, flags);
-
-		for (n = 0; n < ARRAY_SIZE(engine->execlist_port); n++)
-			i915_gem_request_put(port_request(&port[n]));
-		memset(engine->execlist_port, 0, sizeof(engine->execlist_port));
-		engine->execlist_queue = RB_ROOT;
-		engine->execlist_first = NULL;
-
-		spin_unlock_irqrestore(&engine->timeline->lock, flags);
-
-		/* The port is checked prior to scheduling a tasklet, but
-		 * just in case we have suspended the tasklet to do the
-		 * wedging make sure that when it wakes, it decides there
-		 * is no work to do by clearing the irq_posted bit.
-		 */
-		clear_bit(ENGINE_IRQ_EXECLIST, &engine->irq_posted);
-	}
+	engine->cancel_requests(engine);
 
 	/* Mark all pending requests as complete so that any concurrent
 	 * (lockless) lookup doesn't try and wait upon the request as we