drm/i915: Check for timeout completion when waiting for the rq to submitted

We first wait for a request to be submitted to hw and assigned a seqno,
before we can wait for the hw to signal completion (otherwise we don't
know the hw id we need to wait upon). Whilst waiting for the request to
be submitted, we may exceed the user's timeout and need to propagate the
error back.

v2: Make ETIME into an error from wait_for_execute for consistent exit
handling.

Reported-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Fixes: 4680816be336 ("drm/i915: Wait first for submission, before waiting for request completion")
Testcase: igt/gem_wait/basic-await
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: <drm-intel-fixes@lists.freedesktop.org> # v4.10-rc1+
Cc: stable@vger.kernel.org
Link: http://patchwork.freedesktop.org/patch/msgid/20170208181238.7232-1-chris@chris-wilson.co.uk
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

drivers/gpu/drm/i915/i915_gem_request.c

@@ -1025,8 +1025,13 @@ __i915_request_wait_for_execute(struct drm_i915_gem_request *request,
 			break;
 		}
 
+		if (!timeout) {
+			timeout = -ETIME;
+			break;
+		}
+
 		timeout = io_schedule_timeout(timeout);
-	} while (timeout);
+	} while (1);
 	finish_wait(&request->execute.wait, &wait);
 
 	if (flags & I915_WAIT_LOCKED)