Subject: Re: [PATCH net-next] vhost_net: do not stall on zerocopy depletion

From: "Michael S. Tsirkin" <[email-masked]>
Date: Sun, 1 Oct 2017 06:20:49 +0300

On Sun, Oct 01, 2017 at 08:09:30AM +0800, kbuild test robot wrote:
> Hi Willem,
> 
> [auto build test WARNING on net-next/master]
> 
> url:    https://github.com/0day-ci/linux/commits/Willem-de-Bruijn/vhost_net-do-not-stall-on-zerocopy-depletion/20171001-054709
> reproduce:
>         # apt-get install sparse
>         make ARCH=x86_64 allmodconfig
>         make C=1 CF=-D__CHECK_ENDIAN__

BTW __CHECK_ENDIAN__ is the default now, I think you can drop it from
your scripts.

> 
> sparse warnings: (new ones prefixed by >>)
> 
> 
> vim +440 drivers/vhost/net.c
> 
>    433	
>    434	static bool vhost_exceeds_maxpend(struct vhost_net *net)
>    435	{
>    436		struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
>    437		struct vhost_virtqueue *vq = &nvq->vq;
>    438	
>    439		return (nvq->upend_idx + UIO_MAXIOV - nvq->done_idx) % UIO_MAXIOV >
>  > 440		       min(VHOST_MAX_PEND, vq->num >> 2);
>    441	}
>    442	
> 
> ---
> 0-DAY kernel test infrastructure                Open Source Technology Center
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