Re: [Qemu-devel] [PATCH] socket: dont't free msgfds if error equals EAGAIN

[Peter Xu <peterx@redhat.com>]

On Tue, May 29, 2018 at 10:52:40AM +0800, linzhecheng wrote:
> Signed-off-by: linzhecheng <linzhecheng@huawei.com>
> 
> diff --git a/chardev/char-socket.c b/chardev/char-socket.c
> index 159e69c3b1..17519ec589 100644
> --- a/chardev/char-socket.c
> +++ b/chardev/char-socket.c
> @@ -134,8 +134,8 @@ static int tcp_chr_write(Chardev *chr, const uint8_t *buf, int len)
>                                          s->write_msgfds,
>                                          s->write_msgfds_num);
>  
> -        /* free the written msgfds, no matter what */
> -        if (s->write_msgfds_num) {
> +        /* free the written msgfds in any cases other than errno==EAGAIN */
> +        if (EAGAIN != errno && s->write_msgfds_num) {

This makes sense to me.

Meanwhile this reminds me that we didn't release the fds in
tcp_chr_disconnect().  I'm thinking whether we should do that no
matter what.  E.g., what if we set_msgfds() then another operation
instead of write() failed?

Then here we can only release the msgfds when write succeeded...

  if (ret >= 0 && s->write_msgfds_num) {
 
...as long as we'll also cleanup the msgfds in tcp_chr_disconnect()
always.

I'll see how Marc-Andre and Paolo see this though.

Thanks,

>              g_free(s->write_msgfds);
>              s->write_msgfds = 0;
>              s->write_msgfds_num = 0;
> -- 
> 2.12.2.windows.2
> 
> 
> 

-- 
Peter Xu