drm/i915: Add ourselves to the gpu error waitqueue for the entire wait

Add ourselves to the gpu error waitqueue earlier on, even before we
determine we have to wait on the seqno. This is so that we can then
share the waitqueue between stages in subsequent patches.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170223074422.4125-6-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/i915_gem_request.c

@@ -1097,6 +1097,9 @@ long i915_wait_request(struct drm_i915_gem_request *req,
 
 	trace_i915_gem_request_wait_begin(req, flags);
 
+	if (flags & I915_WAIT_LOCKED)
+		add_wait_queue(errq, &reset);
+
 	if (!i915_sw_fence_done(&req->execute)) {
 		timeout = __i915_request_wait_for_execute(req, flags, timeout);
 		if (timeout < 0)
@@ -1112,9 +1115,6 @@ long i915_wait_request(struct drm_i915_gem_request *req,
 		goto complete;
 
 	set_current_state(state);
-	if (flags & I915_WAIT_LOCKED)
-		add_wait_queue(errq, &reset);
-
 	intel_wait_init(&wait, req->global_seqno);
 	if (intel_engine_add_wait(req->engine, &wait))
 		/* In order to check that we haven't missed the interrupt
@@ -1174,11 +1174,11 @@ long i915_wait_request(struct drm_i915_gem_request *req,
 	}
 
 	intel_engine_remove_wait(req->engine, &wait);
-	if (flags & I915_WAIT_LOCKED)
-		remove_wait_queue(errq, &reset);
 	__set_current_state(TASK_RUNNING);
 
 complete:
+	if (flags & I915_WAIT_LOCKED)
+		remove_wait_queue(errq, &reset);
 	trace_i915_gem_request_wait_end(req);
 
 	return timeout;