Re: drivers/vhost/net.c:1010 vhost_net_rx_peek_head_len() error: double unlocked 'sk->sk_receive_queue.lock' (orig line 1002)

[Jason Wang]

On 2020/8/10 下午8:33, Michael S. Tsirkin wrote:
> On Sat, Aug 08, 2020 at 03:37:07PM +0800, kernel test robot wrote:
> > Hi Jason,
> >
> > First bad commit (maybe != root cause):
> >
> > tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> > head:   449dc8c97089a6e09fb2dac4d92b1b7ac0eb7c1e
> > commit: 20c384f1ea1a0bc7320bc445c72dd02d2970d594 vhost: refine vhost and vringh kconfig
> > date:   4 months ago
> > config: arm-randconfig-m031-20200808 (attached as .config)
> > compiler: arm-linux-gnueabi-gcc (GCC) 9.3.0
> >
> > If you fix the issue, kindly add following tag as appropriate
> > Reported-by: kernel test robot <lkp@xxxxxxxxx>
> >
> > New smatch warnings:
> > drivers/vhost/net.c:1010 vhost_net_rx_peek_head_len() error: double unlocked 'sk->sk_receive_queue.lock' (orig line 1002)
> > drivers/vhost/net.c:1010 vhost_net_rx_peek_head_len() error: double unlocked 'sk->sk_receive_queue.lock' (orig line 1002)
> Weird. Can't figure out where the double unlock is ...


Yes, looks like a false positive.

Thanks


> > Old smatch warnings:
> > drivers/vhost/net.c:1528 vhost_net_set_backend() warn: passing a valid pointer to 'PTR_ERR'
> this stumped me too...
>
> > vim +1010 drivers/vhost/net.c
> >
> > 8dd014adfea6f17 David Stevens   2010-07-27   994
> > be294a51adfc1e1 Toshiaki Makita 2018-07-03   995  static int vhost_net_rx_peek_head_len(struct vhost_net *net, struct sock *sk,
> > be294a51adfc1e1 Toshiaki Makita 2018-07-03   996  				      bool *busyloop_intr)
> > 030881372460654 Jason Wang      2016-03-04   997  {
> > 28b9b33b983f4de Toshiaki Makita 2018-07-03   998  	struct vhost_net_virtqueue *rnvq = &net->vqs[VHOST_NET_VQ_RX];
> > 28b9b33b983f4de Toshiaki Makita 2018-07-03   999  	struct vhost_net_virtqueue *tnvq = &net->vqs[VHOST_NET_VQ_TX];
> > 6369fec5be0aad4 Toshiaki Makita 2018-07-03  1000  	struct vhost_virtqueue *rvq = &rnvq->vq;
> > 28b9b33b983f4de Toshiaki Makita 2018-07-03  1001  	struct vhost_virtqueue *tvq = &tnvq->vq;
> > 28b9b33b983f4de Toshiaki Makita 2018-07-03 @1002  	int len = peek_head_len(rnvq, sk);
> > 030881372460654 Jason Wang      2016-03-04  1003
> > dc151282bbdaed0 Tonghao Zhang   2018-09-25  1004  	if (!len && rvq->busyloop_timeout) {
> > f5a4941aa6d190e Jason Wang      2018-05-29  1005  		/* Flush batched heads first */
> > 09c3248938c3e3b Jason Wang      2018-07-20  1006  		vhost_net_signal_used(rnvq);
> > 030881372460654 Jason Wang      2016-03-04  1007  		/* Both tx vq and rx socket were polled here */
> > dc151282bbdaed0 Tonghao Zhang   2018-09-25  1008  		vhost_net_busy_poll(net, rvq, tvq, busyloop_intr, true);
> > 030881372460654 Jason Wang      2016-03-04  1009
> > 28b9b33b983f4de Toshiaki Makita 2018-07-03 @1010  		len = peek_head_len(rnvq, sk);
> > 030881372460654 Jason Wang      2016-03-04  1011  	}
> > 030881372460654 Jason Wang      2016-03-04  1012
> > 030881372460654 Jason Wang      2016-03-04  1013  	return len;
> > 030881372460654 Jason Wang      2016-03-04  1014  }
> > 030881372460654 Jason Wang      2016-03-04  1015
> >
> > :::::: The code at line 1010 was first introduced by commit
> > :::::: 28b9b33b983f4de3ce9e660e3efe1e08adabf779 vhost_net: Rename local variables in vhost_net_rx_peek_head_len
> >
> > :::::: TO: Toshiaki Makita <makita.toshiaki@xxxxxxxxxxxxx>
> > :::::: CC: David S. Miller <davem@xxxxxxxxxxxxx>
> >
> > ---
> > 0-DAY CI Kernel Test Service, Intel Corporation
> > https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx