linux-kernel - Re: [PATCH net] vhost_net: don't continue to call the recvmsg when meet errors

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Message-ID: <e4ac063d-db9f-ec93-30cd-163375ececfc@redhat.com>
Date:   Wed, 30 Nov 2016 21:07:16 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     Yunjian Wang <wangyunjian@...wei.com>, mst@...hat.com,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     caihe@...wei.com
Subject: Re: [PATCH net] vhost_net: don't continue to call the recvmsg when
 meet errors



On 2016年11月30日 20:10, Yunjian Wang wrote:
> When we meet an error(err=-EBADFD) recvmsg, the error handling in vhost
> handle_rx() will continue. This will cause a soft CPU lockup in vhost thread.
>
> Signed-off-by: Yunjian Wang <wangyunjian@...wei.com>
> ---
>   drivers/vhost/net.c | 3 +++
>   1 file changed, 3 insertions(+)
>
> diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
> index 5dc128a..edc470b 100644
> --- a/drivers/vhost/net.c
> +++ b/drivers/vhost/net.c
> @@ -717,6 +717,9 @@ static void handle_rx(struct vhost_net *net)
>   			pr_debug("Discarded rx packet: "
>   				 " len %d, expected %zd\n", err, sock_len);
>   			vhost_discard_vq_desc(vq, headcount);
> +			/* Don't continue to do, when meet errors. */
> +			if (err < 0)
> +				goto out;
>   			continue;
>   		}
>   		/* Supply virtio_net_hdr if VHOST_NET_F_VIRTIO_NET_HDR */

Acked-by: Jason Wang <jasowang@...hat.com>

We may want to rename vhost_discard_vq_desc() in the future, since it 
does not discard the desc in fact.