From: Daniel Vetter <daniel.vetter@ffwll.ch>
Date: Thu, 9 Jul 2015 21:32:40 +0000 (+0200)
Subject: drm/cirrus: Don't grab dev->struct_mutex for in mmap offset ioctl
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=6cc56234fe4d76a4c0cfefbf196a33718ba9db73;p=GitHub%2Fexynos8895%2Fandroid_kernel_samsung_universal8895.git

drm/cirrus: 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/cirrus/cirrus_main.c b/drivers/gpu/drm/cirrus/cirrus_main.c
index e4b976658087..055fd86ba717 100644
--- a/drivers/gpu/drm/cirrus/cirrus_main.c
+++ b/drivers/gpu/drm/cirrus/cirrus_main.c
@@ -293,25 +293,18 @@ cirrus_dumb_mmap_offset(struct drm_file *file,
 		     uint64_t *offset)
 {
 	struct drm_gem_object *obj;
-	int ret;
 	struct cirrus_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_cirrus_bo(obj);
 	*offset = cirrus_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;
 }
 
 bool cirrus_check_framebuffer(struct cirrus_device *cdev, int width, int height,