Re: [PATCH v2] chardev: add nodelay option

[Markus Armbruster <armbru@redhat.com>]

Paolo Bonzini <pbonzini@redhat.com> writes:

> The "delay" option was introduced as a way to enable Nagle's algorithm
> with ",nodelay".  Since the short form for boolean options has now been
> deprecated, introduce a more properly named "nodelay" option.  The "delay"
> option remains as an undocumented option.
>
> "delay" and "nodelay" are mutually exclusive.  Because the check is
> done at consumption time, the code also rejects them if one of the
> two is specified via -set.
>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  chardev/char-socket.c | 13 +++++++++++--
>  gdbstub.c             |  2 +-
>  qemu-options.hx       | 14 +++++++-------
>  3 files changed, 19 insertions(+), 10 deletions(-)

I believe this is
Based-on: <20210226080526.651705-1-pbonzini@redhat.com>

>
> diff --git a/chardev/char-socket.c b/chardev/char-socket.c
> index 06a37c0cc8..c8bced76b7 100644
> --- a/chardev/char-socket.c
> +++ b/chardev/char-socket.c
> @@ -1472,8 +1472,17 @@ static void qemu_chr_parse_socket(QemuOpts *opts, ChardevBackend *backend,
>      sock = backend->u.socket.data = g_new0(ChardevSocket, 1);
>      qemu_chr_parse_common(opts, qapi_ChardevSocket_base(sock));
>  
> -    sock->has_nodelay = qemu_opt_get(opts, "delay");
> -    sock->nodelay = !qemu_opt_get_bool(opts, "delay", true);
> +    if (qemu_opt_get(opts, "delay") && qemu_opt_get(opts, "nodelay")) {
> +        error_setg(errp, "'delay' and 'nodelay' are mutually exclusive");
> +        return;
> +    }
> +    sock->has_nodelay =
> +        qemu_opt_get(opts, "delay") ||
> +        qemu_opt_get(opts, "nodelay");
> +    sock->nodelay =
> +        !qemu_opt_get_bool(opts, "delay", true) ||
> +        qemu_opt_get_bool(opts, "nodelay", false);
> +
>      /*
>       * We have different default to QMP for 'server', hence
>       * we can't just check for existence of 'server'

$ qemu-system-x86_64 -chardev socket,id=chr0,path=sock,nodelay=on
qemu-system-x86_64: -chardev socket,id=chr0,path=sock,nodelay=on: Invalid parameter 'nodelay'

You forgot to update qemu_chardev_opts:

   diff --git a/chardev/char.c b/chardev/char.c
   index 288efebd12..e6128c046f 100644
   --- a/chardev/char.c
   +++ b/chardev/char.c
   @@ -864,6 +864,9 @@ QemuOptsList qemu_chardev_opts = {
            },{
                .name = "server",
                .type = QEMU_OPT_BOOL,
   +        },{
   +            .name = "nodelay",
   +            .type = QEMU_OPT_BOOL,
            },{
                .name = "delay",
                .type = QEMU_OPT_BOOL,

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