drm/i915: Construct a request even if the GPU is currently hung

As we now have the ability to directly reset the GPU from the waiter
(and so do not need to drop the lock in order to let the reset proceed)
and also do not lose requests over a reset, we can now simply queue the
request to occur after the reset rather than roundtripping to userspace
(or worse failing with EIO).
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20170114162334.10271-1-chris@chris-wilson.co.ukReviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>

drivers/gpu/drm/i915/i915_gem_request.c

@@ -307,26 +307,6 @@ void i915_gem_request_retire_upto(struct drm_i915_gem_request *req)
 	} while (tmp != req);
 }
 
-static int i915_gem_check_wedge(struct drm_i915_private *dev_priv)
-{
-	struct i915_gpu_error *error = &dev_priv->gpu_error;
-
-	if (i915_terminally_wedged(error))
-		return -EIO;
-
-	if (i915_reset_in_progress(error)) {
-		/* Non-interruptible callers can't handle -EAGAIN, hence return
-		 * -EIO unconditionally for these.
-		 */
-		if (!dev_priv->mm.interruptible)
-			return -EIO;
-
-		return -EAGAIN;
-	}
-
-	return 0;
-}
-
 static int i915_gem_init_global_seqno(struct drm_i915_private *i915, u32 seqno)
 {
 	struct i915_gem_timeline *timeline = &i915->gt.global_timeline;
@@ -521,12 +501,10 @@ i915_gem_request_alloc(struct intel_engine_cs *engine,
 	lockdep_assert_held(&dev_priv->drm.struct_mutex);
 
 	/* ABI: Before userspace accesses the GPU (e.g. execbuffer), report
-	 * EIO if the GPU is already wedged, or EAGAIN to drop the struct_mutex
-	 * and restart.
+	 * EIO if the GPU is already wedged.
 	 */
-	ret = i915_gem_check_wedge(dev_priv);
-	if (ret)
-		return ERR_PTR(ret);
+	if (i915_terminally_wedged(&dev_priv->gpu_error))
+		return ERR_PTR(-EIO);
 
 	/* Pinning the contexts may generate requests in order to acquire
 	 * GGTT space, so do this first before we reserve a seqno for