Looking up an obj, immediate dropping the acquired reference and then
continuing to use it isn't how this is supposed to work. Fix this by
holding a reference for the entire function.

While at it stop grabbing dev->struct_mutex, it doesn't protect
anything here.

Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
---
 drivers/gpu/drm/mgag200/mgag200_cursor.c | 22 ++++++++++------------
 1 file changed, 10 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/mgag200/mgag200_cursor.c 
b/drivers/gpu/drm/mgag200/mgag200_cursor.c
index 9f9780b7ddf0..4f2068fe5d88 100644
--- a/drivers/gpu/drm/mgag200/mgag200_cursor.c
+++ b/drivers/gpu/drm/mgag200/mgag200_cursor.c
@@ -70,18 +70,22 @@ int mga_crtc_cursor_set(struct drm_crtc *crtc,
        BUG_ON(pixels_2 != pixels_current && pixels_2 != pixels_prev);
        BUG_ON(pixels_current == pixels_prev);

+       obj = drm_gem_object_lookup(dev, file_priv, handle);
+       if (!obj)
+               return -ENOENT;
+
        ret = mgag200_bo_reserve(pixels_1, true);
        if (ret) {
                WREG8(MGA_CURPOSXL, 0);
                WREG8(MGA_CURPOSXH, 0);
-               return ret;
+               goto out_unref;
        }
        ret = mgag200_bo_reserve(pixels_2, true);
        if (ret) {
                WREG8(MGA_CURPOSXL, 0);
                WREG8(MGA_CURPOSXH, 0);
                mgag200_bo_unreserve(pixels_1);
-               return ret;
+               goto out_unreserve1;
        }

        if (!handle) {
@@ -106,16 +110,6 @@ int mga_crtc_cursor_set(struct drm_crtc *crtc,
                }
        }

-       mutex_lock(&dev->struct_mutex);
-       obj = drm_gem_object_lookup(dev, file_priv, handle);
-       if (!obj) {
-               mutex_unlock(&dev->struct_mutex);
-               ret = -ENOENT;
-               goto out1;
-       }
-       drm_gem_object_unreference(obj);
-       mutex_unlock(&dev->struct_mutex);
-
        bo = gem_to_mga_bo(obj);
        ret = mgag200_bo_reserve(bo, true);
        if (ret) {
@@ -252,7 +246,11 @@ int mga_crtc_cursor_set(struct drm_crtc *crtc,
        if (ret)
                mga_hide_cursor(mdev);
        mgag200_bo_unreserve(pixels_1);
+out_unreserve1:
        mgag200_bo_unreserve(pixels_2);
+out_unref:
+       drm_gem_object_unreference_unlocked(obj);
+
        return ret;
 }

-- 
2.1.4

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