Re: [PATCH] vhost: fix connect hang in client mode

[Yuanhan Liu <yuanhan.liu@linux.intel.com>]

On Thu, Jul 21, 2016 at 02:14:59PM +0300, Ilya Maximets wrote:
> > Hmm, how about this fixup:
> > ------------------------------------------------------------------------------
> > diff --git a/lib/librte_vhost/vhost_user/vhost-net-user.c b/lib/librte_vhost/vhost_user/vhost-net-user.c
> > index 8626d13..b0f45e6 100644
> > --- a/lib/librte_vhost/vhost_user/vhost-net-user.c
> > +++ b/lib/librte_vhost/vhost_user/vhost-net-user.c
> > @@ -537,18 +537,7 @@ vhost_user_connect_nonblock(int fd, struct sockaddr *un, size_t sz)
> >  	errno = EINVAL;
> >  
> >  	ret = connect(fd, un, sz);
> > -	if (ret == -1 && errno != EINPROGRESS)
> > -		return -1;
> > -	if (ret == 0)
> > -		goto connected;
> > -
> > -	FD_ZERO(&fdset);
> > -	FD_SET(fd, &fdset);
> > -
> > -	ret = select(fd + 1, NULL, &fdset, NULL, &tv);
> > -	if (!ret)
> > -		errno = ETIMEDOUT;
> > -	if (ret != 1)
> > +	if (ret < 0 && errno != EISCONN)
> >  		return -1;
> >  
> >  	ret = getsockopt(fd, SOL_SOCKET, SO_ERROR, &so_error, &len);
> > @@ -558,7 +547,6 @@ vhost_user_connect_nonblock(int fd, struct sockaddr *un, size_t sz)
> >  		return -1;
> >  	}
> >  
> > -connected:
> >  	flags = fcntl(fd, F_GETFL, 0);
> >  	if (flags < 0) {
> >  		RTE_LOG(ERR, VHOST_CONFIG,
> > ------------------------------------------------------------------------------
> > ?
> > 
> > We will not check the EINPROGRESS, but subsequent 'connect()' will return
> > EISCONN if connection already established. getsockopt() is kept just in
> > case. Subsequent 'connect()' will happen on the next iteration of
> > reconnection cycle (1 second sleep).
> 
> I've sent v2 with this changes.

Thanks. But still, it doesn't look clean to me. I was thinking following
might be cleaner?

    diff --git a/lib/librte_vhost/vhost_user/vhost-net-user.c
    b/lib/librte_vhost/vhost_user/vhost-net-user.
    index f0f92f8..c0ef290 100644
    --- a/lib/librte_vhost/vhost_user/vhost-net-user.c
    +++ b/lib/librte_vhost/vhost_user/vhost-net-user.c
    @@ -532,6 +532,10 @@ vhost_user_client_reconnect(void *arg __rte_unused)
                         reconn != NULL; reconn = next) {
                            next = TAILQ_NEXT(reconn, next);
    
    +                       if (reconn->conn_inprogress) {
    +                               /* do connect check here */
    +                       }
    +
                            if (connect(reconn->fd, (struct sockaddr *)&reconn->un,
                                        sizeof(reconn->un)) < 0)
                                    continue;
    @@ -605,6 +609,7 @@ vhost_user_create_client(struct vhost_user_socket *vsocket)
            reconn->un = un;
            reconn->fd = fd;
            reconn->vsocket = vsocket;
    +       reconn->conn_inprogress = errno == EINPROGRESS;
            pthread_mutex_lock(&reconn_list.mutex);
            TAILQ_INSERT_TAIL(&reconn_list.head, reconn, next);
            pthread_mutex_unlock(&reconn_list.mutex);

It's just a rough diff, hopefully it shows my idea clearly. And of
course, we should not call connect() anymore when conn_inprogress
is set.

What do you think of it?

	--yliu