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

On Wed, Nov 30, 2016 at 09:07:16PM +0800, Jason Wang wrote:

On 2016年11月30日 20:10, Yunjian Wang wrote:

quoted

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 <redacted>
---
  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 <redacted>

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

To me this looks a bit too aggressive. I would also like commit log
to explain better what is going on, to make sure we are
not just treating the symptoms.
-- 
MST