From: Daniel Vetter <daniel.vetter@ffwll.ch>
Date: Thu, 9 Jul 2015 21:32:38 +0000 (+0200)
Subject: drm/mga200g: Don't grab dev->struct_mutex for in mmap offset ioctl
X-Git-Tag: firefly_0821_release~176^2~1083^2~36^2~27
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=34c294f5a6c0dca7fb75ddc1be3ec8974b24455f;p=firefly-linux-kernel-4.4.55.git

drm/mga200g: Don't grab dev->struct_mutex for in mmap offset ioctl

Since David Herrmann's mmap vma manager rework we don't need to grab
dev->struct_mutex any more to prevent races when looking up the mmap
offset. Drop it and instead don't forget to use the unref_unlocked
variant (since the drm core still cares).

Reviewed-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
---

diff --git a/drivers/gpu/drm/mgag200/mgag200_main.c b/drivers/gpu/drm/mgag200/mgag200_main.c
index f6b283b8375e..c99c2cb28939 100644
--- a/drivers/gpu/drm/mgag200/mgag200_main.c
+++ b/drivers/gpu/drm/mgag200/mgag200_main.c
@@ -345,23 +345,15 @@ mgag200_dumb_mmap_offset(struct drm_file *file,
 		     uint64_t *offset)
 {
 	struct drm_gem_object *obj;
-	int ret;
 	struct mgag200_bo *bo;
 
-	mutex_lock(&dev->struct_mutex);
 	obj = drm_gem_object_lookup(dev, file, handle);
-	if (obj == NULL) {
-		ret = -ENOENT;
-		goto out_unlock;
-	}
+	if (obj == NULL)
+		return -ENOENT;
 
 	bo = gem_to_mga_bo(obj);
 	*offset = mgag200_bo_mmap_offset(bo);
 
-	drm_gem_object_unreference(obj);
-	ret = 0;
-out_unlock:
-	mutex_unlock(&dev->struct_mutex);
-	return ret;
-
+	drm_gem_object_unreference_unlocked(obj);
+	return 0;
 }