Hi, Leo,
On Mon, Jul 04, 2022 at 05:23:13PM -0300, Leonardo Bras wrote:
> If flush is called when no buffer was sent with MSG_ZEROCOPY, it currently
> returns 1. This return code should be used only when Linux fails to use
> MSG_ZEROCOPY on a lot of sendmsg().
>
> Fix this by returning early from flush if no sendmsg(...,MSG_ZEROCOPY)
> was attempted.
>
> Fixes: 2bc58ffc2926 ("QIOChannelSocket: Implement io_writev zero copy flag &
> io_flush for CONFIG_LINUX")
> Signed-off-by: Leonardo Bras <leob...@redhat.com>
> ---
> io/channel-socket.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/io/channel-socket.c b/io/channel-socket.c
> index 4466bb1cd4..698c086b70 100644
> --- a/io/channel-socket.c
> +++ b/io/channel-socket.c
> @@ -716,12 +716,18 @@ static int qio_channel_socket_flush(QIOChannel *ioc,
> struct cmsghdr *cm;
> char control[CMSG_SPACE(sizeof(*serr))];
> int received;
> - int ret = 1;
> + int ret;
> +
> + if (!sioc->zero_copy_queued) {
I think I asked this in the downstream review but didn't get a
response.. shouldn't this check be "queued == sent"?
> + return 0;
> + }
>
> msg.msg_control = control;
> msg.msg_controllen = sizeof(control);
> memset(control, 0, sizeof(control));
>
> + ret = 1;
> +
> while (sioc->zero_copy_sent < sioc->zero_copy_queued) {
> received = recvmsg(sioc->fd, &msg, MSG_ERRQUEUE);
> if (received < 0) {
> --
> 2.36.1
>
--
Peter Xu
