> -----Original Message-----
> From: Wang, YuanX <yuanx.w...@intel.com>
> Sent: Friday, June 17, 2022 10:42 AM
> To: maxime.coque...@redhat.com; Xia, Chenbo <chenbo....@intel.com>;
> dev@dpdk.org
> Cc: Hu, Jiayu <jiayu...@intel.com>; He, Xingguang <xingguang...@intel.com>;
> Wang, YuanX <yuanx.w...@intel.com>; sta...@dpdk.org
> Subject: [PATCH] net/virtio: fix socket nonblocking mode affects
> initialization
>
> The virtio-user initialization requires unix socket to receive backend
> messages in block mode. However, vhost_user_update_link_state() sets
> the same socket to nonblocking via fcntl, which affects all threads.
> Enabling the rxq interrupt can causes both of these behaviors to occur
> concurrently, with the result that the initialization may fail
> because no messages are received in nonblocking socket.
>
> Thread 1:
> virtio_init_device()
> --> virtio_user_start_device()
> --> vhost_user_set_memory_table()
> --> vhost_user_check_reply_ack()
>
> Thread 2:
> virtio_interrupt_handler()
> --> vhost_user_update_link_state()
>
> Fix that by replacing O_NONBLOCK with the recv per-call option
> MSG_DONTWAIT.
>
> Fixes: ef53b6030039 ("net/virtio-user: support LSC")
> Cc: sta...@dpdk.org
>
> Signed-off-by: Yuan Wang <yuanx.w...@intel.com>
> ---
> drivers/net/virtio/virtio_user/vhost_user.c | 15 +--------------
> 1 file changed, 1 insertion(+), 14 deletions(-)
>
> diff --git a/drivers/net/virtio/virtio_user/vhost_user.c
> b/drivers/net/virtio/virtio_user/vhost_user.c
> index 7d1749114d..198bd63d3c 100644
> --- a/drivers/net/virtio/virtio_user/vhost_user.c
> +++ b/drivers/net/virtio/virtio_user/vhost_user.c
> @@ -940,15 +940,8 @@ vhost_user_update_link_state(struct virtio_user_dev
> *dev)
>
> if (data->vhostfd >= 0) {
> int r;
> - int flags;
>
> - flags = fcntl(data->vhostfd, F_GETFL);
> - if (fcntl(data->vhostfd, F_SETFL, flags | O_NONBLOCK) == -1) {
> - PMD_DRV_LOG(ERR, "error setting O_NONBLOCK flag");
> - return -1;
> - }
> -
> - r = recv(data->vhostfd, buf, 128, MSG_PEEK);
> + r = recv(data->vhostfd, buf, 128, MSG_PEEK | MSG_DONTWAIT);
> if (r == 0 || (r < 0 && errno != EAGAIN)) {
> dev->net_status &= (~VIRTIO_NET_S_LINK_UP);
> PMD_DRV_LOG(ERR, "virtio-user port %u is down", dev-
> >hw.port_id);
> @@ -963,12 +956,6 @@ vhost_user_update_link_state(struct virtio_user_dev
> *dev)
> } else {
> dev->net_status |= VIRTIO_NET_S_LINK_UP;
> }
> -
> - if (fcntl(data->vhostfd, F_SETFL,
> - flags & ~O_NONBLOCK) == -1) {
> - PMD_DRV_LOG(ERR, "error clearing O_NONBLOCK flag");
> - return -1;
> - }
> } else if (dev->is_server) {
> dev->net_status &= (~VIRTIO_NET_S_LINK_UP);
> if (virtio_user_dev_server_reconnect(dev) >= 0)
> --
> 2.25.1
Reviewed-by: Chenbo Xia <chenbo....@intel.com>
