Re: [Qemu-devel] [PATCH 1/4] net: ensure "socket" backend uses non-blocking fds

[Juan Quintela <quintela@redhat.com>]

Stefan Hajnoczi <stefanha@redhat.com> wrote:
> There are several code paths in net_init_socket() depending on how the
> socket is created: file descriptor passing, UDP multicast, TCP, or UDP.
> Some of these support both listen and connect.
>
> Not all code paths set the socket to non-blocking.  This patch addresses
> the file descriptor passing and UDP cases which were missing
> socket_set_nonblock(fd) calls.
>
> I considered moving socket_set_nonblock(fd) to a central location but it
> turns out the code paths are different enough to require non-blocking at
> different places.
>
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
>  net/socket.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/net/socket.c b/net/socket.c
> index 6c3752b..4a88142 100644
> --- a/net/socket.c
> +++ b/net/socket.c
> @@ -674,6 +674,7 @@ static int net_socket_udp_init(NetClientState *peer,
>          closesocket(fd);
>          return -1;
>      }
> +    socket_set_nonblock(fd);
>  
>      s = net_socket_fd_init(peer, model, name, fd, 0);
>      if (!s) {
> @@ -712,6 +713,7 @@ int net_init_socket(const NetClientOptions *opts, const char *name,
>          int fd;
>  
>          fd = monitor_handle_fd_param(cur_mon, sock->fd);
> +        socket_set_nonblock(fd);
>          if (fd == -1 || !net_socket_fd_init(peer, "socket", name, fd, 1)) {

Shouldn't be better to refactor the code to _not_ call
socket_set_nonblock() in the case that fd == -1?  It will just clobber
errno?

>              return -1;
>          }