drm/i915: Return error from i915_gem_object_get_fence_reg() when failing.

Previously, the caller would continue along without knowing that the
function failed, resulting in potential mis-rendering.  Right now vm_fault
just returns SIGBUS in that case, and we may need to disable signal handling
to avoid that happening.

Signed-off-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Dave Airlie <airlied@linux.ie>

1 files changed, 13 insertions, 7 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index af8034d52511..e1f831f166ca 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -52,7 +52,7 @@ static void i915_gem_object_free_page_list(struct drm_gem_object *obj);
 static int i915_gem_object_wait_rendering(struct drm_gem_object *obj);
 static int i915_gem_object_bind_to_gtt(struct drm_gem_object *obj,
                                            unsigned alignment);
-static void i915_gem_object_get_fence_reg(struct drm_gem_object *obj);
+static int i915_gem_object_get_fence_reg(struct drm_gem_object *obj);
 static void i915_gem_clear_fence_reg(struct drm_gem_object *obj);
 static int i915_gem_evict_something(struct drm_device *dev);
 static int i915_gem_phys_pwrite(struct drm_device *dev, struct drm_gem_object *obj,
@@ -585,8 +585,11 @@ int i915_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 
         /* Need a new fence register? */
         if (obj_priv->fence_reg == I915_FENCE_REG_NONE &&
-            obj_priv->tiling_mode != I915_TILING_NONE)
-                i915_gem_object_get_fence_reg(obj);
+            obj_priv->tiling_mode != I915_TILING_NONE) {
+                ret = i915_gem_object_get_fence_reg(obj);
+                if (ret != 0)
+                        return VM_FAULT_SIGBUS;
+        }
 
         pfn = ((dev->agp->base + obj_priv->gtt_offset) >> PAGE_SHIFT) +
                 page_offset;
@@ -1513,7 +1516,7 @@ static void i830_write_fence_reg(struct drm_i915_fence_reg *reg)
  * It then sets up the reg based on the object's properties: address, pitch
  * and tiling format.
  */
-static void
+static int
 i915_gem_object_get_fence_reg(struct drm_gem_object *obj)
 {
         struct drm_device *dev = obj->dev;
@@ -1563,10 +1566,11 @@ try_again:
                  * objects to finish before trying again.
                  */
                 if (i == dev_priv->num_fence_regs) {
-                        ret = i915_gem_object_wait_rendering(reg->obj);
+                        ret = i915_gem_object_set_to_gtt_domain(reg->obj, 0);
                         if (ret) {
-                                WARN(ret, "wait_rendering failed: %d\n", ret);
-                                return;
+                                WARN(ret != -ERESTARTSYS,
+                                     "switch to GTT domain failed: %d\n", ret);
+                                return ret;
                         }
                         goto try_again;
                 }
@@ -1591,6 +1595,8 @@ try_again:
                 i915_write_fence_reg(reg);
         else
                 i830_write_fence_reg(reg);
+
+        return 0;
 }
 
 /**