Re: [PATCH 04/17] vhost: prep vhost_dev_init users to handle failures

[kernel test robot <lkp@intel.com>]

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Hi Mike,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on vhost/linux-next]
[also build test WARNING on v5.9 next-20201021]
[cannot apply to target/for-next]
[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]

url:    https://github.com/0day-ci/linux/commits/Mike-Christie/vhost-fix-scsi-cmd-handling-and-cgroup-support/20201022-083844
base:   https://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git linux-next
config: x86_64-randconfig-a013-20201021 (attached as .config)
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project ee6abef5323d59b983129bf3514ef6775d1d6cd5)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # install x86_64 cross compiling tool for clang build
        # apt-get install binutils-x86-64-linux-gnu
        # https://github.com/0day-ci/linux/commit/6e1629548d318c2c9af7490379a3c9d7e3cba0d5
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Mike-Christie/vhost-fix-scsi-cmd-handling-and-cgroup-support/20201022-083844
        git checkout 6e1629548d318c2c9af7490379a3c9d7e3cba0d5
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

>> drivers/vhost/vsock.c:633:6: warning: variable 'ret' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
           if (vhost_dev_init(&vsock->dev, vqs, ARRAY_SIZE(vsock->vqs),
               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   drivers/vhost/vsock.c:648:9: note: uninitialized use occurs here
           return ret;
                  ^~~
   drivers/vhost/vsock.c:633:2: note: remove the 'if' if its condition is always false
           if (vhost_dev_init(&vsock->dev, vqs, ARRAY_SIZE(vsock->vqs),
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   drivers/vhost/vsock.c:609:9: note: initialize the variable 'ret' to silence this warning
           int ret;
                  ^
                   = 0
   1 warning generated.

vim +633 drivers/vhost/vsock.c

   604	
   605	static int vhost_vsock_dev_open(struct inode *inode, struct file *file)
   606	{
   607		struct vhost_virtqueue **vqs;
   608		struct vhost_vsock *vsock;
   609		int ret;
   610	
   611		/* This struct is large and allocation could fail, fall back to vmalloc
   612		 * if there is no other way.
   613		 */
   614		vsock = kvmalloc(sizeof(*vsock), GFP_KERNEL | __GFP_RETRY_MAYFAIL);
   615		if (!vsock)
   616			return -ENOMEM;
   617	
   618		vqs = kmalloc_array(ARRAY_SIZE(vsock->vqs), sizeof(*vqs), GFP_KERNEL);
   619		if (!vqs) {
   620			ret = -ENOMEM;
   621			goto out;
   622		}
   623	
   624		vsock->guest_cid = 0; /* no CID assigned yet */
   625	
   626		atomic_set(&vsock->queued_replies, 0);
   627	
   628		vqs[VSOCK_VQ_TX] = &vsock->vqs[VSOCK_VQ_TX];
   629		vqs[VSOCK_VQ_RX] = &vsock->vqs[VSOCK_VQ_RX];
   630		vsock->vqs[VSOCK_VQ_TX].handle_kick = vhost_vsock_handle_tx_kick;
   631		vsock->vqs[VSOCK_VQ_RX].handle_kick = vhost_vsock_handle_rx_kick;
   632	
 > 633		if (vhost_dev_init(&vsock->dev, vqs, ARRAY_SIZE(vsock->vqs),
   634				   UIO_MAXIOV, VHOST_VSOCK_PKT_WEIGHT,
   635				   VHOST_VSOCK_WEIGHT, true, NULL))
   636			goto err_dev_init;
   637	
   638		file->private_data = vsock;
   639		spin_lock_init(&vsock->send_pkt_list_lock);
   640		INIT_LIST_HEAD(&vsock->send_pkt_list);
   641		vhost_work_init(&vsock->send_pkt_work, vhost_transport_send_pkt_work);
   642		return 0;
   643	
   644	err_dev_init:
   645		kfree(vqs);
   646	out:
   647		vhost_vsock_free(vsock);
   648		return ret;
   649	}
   650	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

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