Re: [Qemu-devel] [PATCH v1] chardev: fix handling of EAGAIN for TCP chardev

[Aleksey Kuleshov <rndfax@yandex.ru>]

Thank you, Daniel!

22.02.2018, 15:14, "Daniel P. Berrangé" <berrange@redhat.com>:
> When this commit was applied
>
>   commit 9894dc0cdcc397ee5b26370bc53da6d360a363c2
>   Author: Daniel P. Berrange <berrange@redhat.com>
>   Date: Tue Jan 19 11:14:29 2016 +0000
>
>     char: convert from GIOChannel to QIOChannel
>
> The tcp_chr_recv() function was changed to return QIO_CHANNEL_ERR_BLOCK
> which corresonds to -2. As such the handling for EAGAIN was able to be
> removed from tcp_chr_read(). Unfortunately in a later commit:
>
>   commit b6572b4f97a7b126c7b24e165893ed9fe3d72e1f
>   Author: Marc-André Lureau <marcandre.lureau@redhat.com>
>   Date: Fri Mar 11 18:55:24 2016 +0100
>
>     char: translate from QIOChannel error to errno
>
> The tcp_chr_recv() function was changed back to return -1, with errno
> set to EAGAIN, without also re-addding support for this to tcp_chr_read()
>
> Reported-by: Aleksey Kuleshov <rndfax@yandex.ru>
> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
> ---
>  chardev/char-socket.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/chardev/char-socket.c b/chardev/char-socket.c
> index bdd6cff5f6..b15682c362 100644
> --- a/chardev/char-socket.c
> +++ b/chardev/char-socket.c
> @@ -449,7 +449,7 @@ static gboolean tcp_chr_read(QIOChannel *chan, GIOCondition cond, void *opaque)
>          len = s->max_size;
>      }
>      size = tcp_chr_recv(chr, (void *)buf, len);
> - if (size == 0 || size == -1) {
> + if (size == 0 || (size == -1 && errno != EAGAIN)) {
>          /* connection closed */
>          tcp_chr_disconnect(chr);
>      } else if (size > 0) {
> --
> 2.14.3