[Intel-gfx] [PATCH 3/5] drm/i915: fall through pwrite_gtt_slow to the shmem slow path

[Daniel Vetter]

The gtt_pwrite slowpath grabs the userspace memory with
get_user_pages. This will not work for non-page backed memory, like a
gtt mmapped gem object. Hence fall throuh to the shmem paths if we hit
-EFAULT in the gtt paths.

Now the shmem paths have exactly the same problem, but this way we
only need to rearrange the code in one write path.

Signed-Off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
---
 drivers/gpu/drm/i915/i915_gem.c |   24 +++++++++++++++---------
 1 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index e0475ca..9c28d48 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1018,18 +1018,24 @@ i915_gem_pwrite_ioctl(struct drm_device *dev, void *data,
 
 out_unpin:
 		i915_gem_object_unpin(obj);
-	} else {
-		ret = i915_gem_object_set_to_cpu_domain(obj, 1);
-		if (ret)
-			goto out;
 
-		ret = -EFAULT;
-		if (!i915_gem_object_needs_bit17_swizzle(obj))
-			ret = i915_gem_shmem_pwrite_fast(dev, obj, args, file);
-		if (ret == -EFAULT)
-			ret = i915_gem_shmem_pwrite_slow(dev, obj, args, file);
+		if (ret != -EFAULT)
+			goto out;
+		/* Fall through to the shmfs paths because the gtt paths might
+		 * fail with non-page-backed user pointers (e.g. gtt mappings
+		 * when moving data between textures). */
 	}
 
+	ret = i915_gem_object_set_to_cpu_domain(obj, 1);
+	if (ret)
+		goto out;
+
+	ret = -EFAULT;
+	if (!i915_gem_object_needs_bit17_swizzle(obj))
+		ret = i915_gem_shmem_pwrite_fast(dev, obj, args, file);
+	if (ret == -EFAULT)
+		ret = i915_gem_shmem_pwrite_slow(dev, obj, args, file);
+
 out:
 	drm_gem_object_unreference(&obj->base);
 unlock:
-- 
1.7.6