>-----Original Message-----
>From: Michael S. Tsirkin [mailto:m...@redhat.com]
>Sent: Wednesday, November 30, 2016 9:41 PM
>To: wangyunjian
>Cc: jasow...@redhat.com; netdev@vger.kernel.org; linux-ker...@vger.kernel.org;
>caihe
>Subject: Re: [PATCH net] vhost_net: don't continue to call the recvmsg when
>meet errors
>
>On Wed, Nov 30, 2016 at 08:10:57PM +0800, Yunjian Wang wrote:
>> When we meet an error(err=-EBADFD) recvmsg,
>
>How do you get EBADFD? Won't vhost_net_rx_peek_head_len
>return 0 in this case, breaking the loop?
We started many guest VMs while attaching/detaching some virtio-net nics for
loop.
The soft lockup might happened. The err is -EBADFD.
meesage log:
kernel:[609608.510180]BUG: soft lockup - CPU#18 stuck for 23s!
[vhost-60898:126093]
call trace:
[<fffffffa0132967>]vhost_get_vq_desc+0x1e7/0x984 [vhost]
[<fffffffa02037e6>]handle_rx+0x226/0x810 [vhost_net]
[<fffffffa0203de5>]handle_rx_net+0x15/0x20 [vhost_net]
[<fffffffa013160b>]vhost_worker+0xfb/0x1e0 [vhost]
[<fffffffa0131510>]? vhost_dev_reset_owner+0x50/0x50 [vhost]
[<fffffff810a5c7f>]kthread+0xcf/0xe0
[<fffffff810a5bb0>]? kthread_create_on_node+0x140/0x140
[<fffffff81648898>]ret_from_fork+0x58/0x90
[<fffffff810a5bb0>]? kthread_create_on_node+0x140/0x140
>> the error handling in vhost
>> handle_rx() will continue. This will cause a soft CPU lockup in vhost thread.
>>
>> Signed-off-by: Yunjian Wang <wangyunj...@huawei.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;
>
>You might get e.g. EAGAIN and I think you need to retry
>in this case.
>
>> continue;
>> }
>> /* Supply virtio_net_hdr if VHOST_NET_F_VIRTIO_NET_HDR */
>> --
>> 1.9.5.msysgit.1
>>
