From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42579) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eriSA-0001Wh-ER for qemu-devel@nongnu.org; Fri, 02 Mar 2018 06:02:19 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eriS6-0002cL-Hq for qemu-devel@nongnu.org; Fri, 02 Mar 2018 06:02:18 -0500 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:33166 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1eriS6-0002bo-Cy for qemu-devel@nongnu.org; Fri, 02 Mar 2018 06:02:14 -0500 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 75B61E44B5 for ; Fri, 2 Mar 2018 11:02:13 +0000 (UTC) Date: Fri, 2 Mar 2018 11:02:09 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Message-ID: <20180302110209.GE26972@redhat.com> Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= References: <20180301084438.13594-1-peterx@redhat.com> <20180301084438.13594-9-peterx@redhat.com> <20180301154638.GO14643@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH v2 08/15] chardev: allow telnet gsource to switch gcontext List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: Peter Xu , qemu-devel@nongnu.org, Juan Quintela , =?utf-8?Q?Marc-Andr=C3=A9?= Lureau , Markus Armbruster , Stefan Hajnoczi , "Dr . David Alan Gilbert" On Thu, Mar 01, 2018 at 06:16:53PM +0100, Paolo Bonzini wrote: > On 01/03/2018 16:46, Daniel P. Berrang=C3=A9 wrote: > > On Thu, Mar 01, 2018 at 04:44:31PM +0800, Peter Xu wrote: > >> It was originally created by qio_channel_add_watch() so it's always > >> assigning the task to main context. Now we use the new API called > >> qio_channel_add_watch_source() so that we get the GSource handle rat= her > >> than the tag ID. > >> > >> Meanwhile, caching the gsource in SocketChardev.telnet_source so tha= t we > >> can also do dynamic context switch when update read handlers. > > I don't see why we would ever want to dynamically switch the > > GMainContext in use while in middle of reading the telnet greeting. >=20 > Maybe because the remote client hangs in the middle of the telnet > greeting? The user of the Chardev can't know that the initial handshak= e > hasn't been done yet. NB, the chardev will emit the CHR_EVENT_OPENED event once the connection is successfully established, which includes completion of the telnet and/or TLS handshake. I'm just not seeing what code in QEMU would actually trigger a decision to change the GMainContext, in between the accept() of the socket, and the CHR_EVENT_OPENED, since we don't tell anyone that the accept() has actually taken place - they first they'll know of a new client being connected is when the CHR_EVENT_OPENED is emitted. Regards, Daniel --=20 |: https://berrange.com -o- https://www.flickr.com/photos/dberran= ge :| |: https://libvirt.org -o- https://fstop138.berrange.c= om :| |: https://entangle-photo.org -o- https://www.instagram.com/dberran= ge :|