[PATCH] [PATCH RESEND] drm/virtio: fix memory leak of vbuf

[kernel test robot]

Hi Weishi,

kernel test robot noticed the following build warnings:

[auto build test WARNING on drm-misc/drm-misc-next]
[also build test WARNING on drm/drm-next linus/master v6.9-rc7 next-20240508]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Weishi-Li/drm-virtio-fix-memory-leak-of-vbuf/20240507-114452
base:   git://anongit.freedesktop.org/drm/drm-misc drm-misc-next
patch link:    https://lore.kernel.org/r/20240507033814.57906-1-liweishi%40kylinos.cn
patch subject: [PATCH] [PATCH RESEND] drm/virtio: fix memory leak of vbuf
config: i386-buildonly-randconfig-001-20240508 (https://download.01.org/0day-ci/archive/20240509/202405090747.y8ofUE7r-lkp@intel.com/config)
compiler: clang version 18.1.4 (https://github.com/llvm/llvm-project e6c3289804a67ea0bb6a86fadbe454dd93b8d855)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240509/202405090747.y8ofUE7r-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp at intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202405090747.y8ofUE7r-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> drivers/gpu/drm/virtio/virtgpu_vq.c:474:13: warning: variable 'notify' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
     474 |         } else if (ret < 0) {
         |                    ^~~~~~~
   drivers/gpu/drm/virtio/virtgpu_vq.c:487:6: note: uninitialized use occurs here
     487 |         if (notify)
         |             ^~~~~~
   drivers/gpu/drm/virtio/virtgpu_vq.c:474:9: note: remove the 'if' if its condition is always false
     474 |         } else if (ret < 0) {
         |                ^~~~~~~~~~~~~~
     475 |                 free_vbuf(vgdev, vbuf);
         |                 ~~~~~~~~~~~~~~~~~~~~~~~
     476 |         } else {
         |         ~~~~~~
   drivers/gpu/drm/virtio/virtgpu_vq.c:455:13: note: initialize the variable 'notify' to silence this warning
     455 |         bool notify;
         |                    ^
         |                     = 0
   1 warning generated.


vim +474 drivers/gpu/drm/virtio/virtgpu_vq.c

   448	
   449	static void virtio_gpu_queue_cursor(struct virtio_gpu_device *vgdev,
   450					    struct virtio_gpu_vbuffer *vbuf)
   451	{
   452		struct virtqueue *vq = vgdev->cursorq.vq;
   453		struct scatterlist *sgs[1], ccmd;
   454		int idx, ret, outcnt;
   455		bool notify;
   456	
   457		if (!drm_dev_enter(vgdev->ddev, &idx)) {
   458			free_vbuf(vgdev, vbuf);
   459			return;
   460		}
   461	
   462		sg_init_one(&ccmd, vbuf->buf, vbuf->size);
   463		sgs[0] = &ccmd;
   464		outcnt = 1;
   465	
   466		spin_lock(&vgdev->cursorq.qlock);
   467	retry:
   468		ret = virtqueue_add_sgs(vq, sgs, outcnt, 0, vbuf, GFP_ATOMIC);
   469		if (ret == -ENOSPC) {
   470			spin_unlock(&vgdev->cursorq.qlock);
   471			wait_event(vgdev->cursorq.ack_queue, vq->num_free >= outcnt);
   472			spin_lock(&vgdev->cursorq.qlock);
   473			goto retry;
 > 474		} else if (ret < 0) {
   475			free_vbuf(vgdev, vbuf);
   476		} else {
   477			vbuf->seqno = ++vgdev->cursorq.seqno;
   478			trace_virtio_gpu_cmd_queue(vq,
   479				virtio_gpu_vbuf_ctrl_hdr(vbuf),
   480				vbuf->seqno);
   481	
   482			notify = virtqueue_kick_prepare(vq);
   483		}
   484	
   485		spin_unlock(&vgdev->cursorq.qlock);
   486	
   487		if (notify)
   488			virtqueue_notify(vq);
   489	
   490		drm_dev_exit(idx);
   491	}
   492	

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