On Thu, Jul 21, 2016 at 11:21:15AM +0300, Ilya Maximets wrote:
> If something abnormal happened to QEMU, 'connect()' can block calling
> thread (e.g. main thread of OVS) forever or for a really long time.
> This can break whole application or block the reconnection thread.
>
> Example with OVS:
>
> ovs_rcu(urcu2)|WARN|blocked 512000 ms waiting for main to quiesce
> (gdb) bt
> #0 connect () from /lib64/libpthread.so.0
> #1 vhost_user_create_client (vsocket=0xa816e0)
> #2 rte_vhost_driver_register
> #3 netdev_dpdk_vhost_user_construct
> #4 netdev_open (name=0xa664b0 "vhost1")
> [...]
> #11 main
>
> Fix that by setting non-blocking mode for client sockets for connection.
>
> Fixes: 64ab701c3d1e ("vhost: add vhost-user client mode")
Thanks for spotting and fixing yet another bug!
>
> +static int
> +vhost_user_connect_nonblock(int fd, struct sockaddr *un, size_t sz)
I don't quite understand why this is needed: connect() with O_NONBLOCK
flag set is not enough?
--yliu
