1 files changed, 55 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 0b236ea0996c..719a933c5756 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1133,6 +1133,52 @@ i915_gem_object_wait_rendering(struct drm_i915_gem_object *obj,
         return 0;
 }
 
+/* A nonblocking variant of the above wait. This is a highly dangerous routine
+ * as the object state may change during this call.
+ */
+static __must_check int
+i915_gem_object_wait_rendering__nonblocking(struct drm_i915_gem_object *obj,
+                                            bool readonly)
+{
+        struct drm_device *dev = obj->base.dev;
+        struct drm_i915_private *dev_priv = dev->dev_private;
+        struct intel_ring_buffer *ring = obj->ring;
+        u32 seqno;
+        int ret;
+
+        BUG_ON(!mutex_is_locked(&dev->struct_mutex));
+        BUG_ON(!dev_priv->mm.interruptible);
+
+        seqno = readonly ? obj->last_write_seqno : obj->last_read_seqno;
+        if (seqno == 0)
+                return 0;
+
+        ret = i915_gem_check_wedge(dev_priv, true);
+        if (ret)
+                return ret;
+
+        ret = i915_gem_check_olr(ring, seqno);
+        if (ret)
+                return ret;
+
+        mutex_unlock(&dev->struct_mutex);
+        ret = __wait_seqno(ring, seqno, true, NULL);
+        mutex_lock(&dev->struct_mutex);
+
+        i915_gem_retire_requests_ring(ring);
+
+        /* Manually manage the write flush as we may have not yet
+         * retired the buffer.
+         */
+        if (obj->last_write_seqno &&
+            i915_seqno_passed(seqno, obj->last_write_seqno)) {
+                obj->last_write_seqno = 0;
+                obj->base.write_domain &= ~I915_GEM_GPU_DOMAINS;
+        }
+
+        return ret;
+}
+
 /**
  * Called when user space prepares to use an object with the CPU, either
  * through the mmap ioctl's mapping or a GTT mapping.
@@ -1170,6 +1216,14 @@ i915_gem_set_domain_ioctl(struct drm_device *dev, void *data,
                 goto unlock;
         }
 
+        /* Try to flush the object off the GPU without holding the lock.
+         * We will repeat the flush holding the lock in the normal manner
+         * to catch cases where we are gazumped.
+         */
+        ret = i915_gem_object_wait_rendering__nonblocking(obj, !write_domain);
+        if (ret)
+                goto unref;
+
         if (read_domains & I915_GEM_DOMAIN_GTT) {
                 ret = i915_gem_object_set_to_gtt_domain(obj, write_domain != 0);
 
@@ -1183,6 +1237,7 @@ i915_gem_set_domain_ioctl(struct drm_device *dev, void *data,
                 ret = i915_gem_object_set_to_cpu_domain(obj, write_domain != 0);
         }
 
+unref:
         drm_gem_object_unreference(&obj->base);
 unlock:
         mutex_unlock(&dev->struct_mutex);