From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:60730) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bYSCj-0002mF-KH for qemu-devel@nongnu.org; Sat, 13 Aug 2016 02:13:58 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bYSCe-0000wD-Ag for qemu-devel@nongnu.org; Sat, 13 Aug 2016 02:13:56 -0400 Received: from mx6-phx2.redhat.com ([209.132.183.39]:37372) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bYSCd-0000vf-Pv for qemu-devel@nongnu.org; Sat, 13 Aug 2016 02:13:52 -0400 Date: Sat, 13 Aug 2016 02:13:46 -0400 (EDT) From: =?utf-8?Q?Marc-Andr=C3=A9?= Lureau Message-ID: <938177459.2407653.1471068826179.JavaMail.zimbra@redhat.com> In-Reply-To: <20160813001158-mutt-send-email-mst@kernel.org> References: <1470842980-32481-1-git-send-email-mst@redhat.com> <1470842980-32481-4-git-send-email-mst@redhat.com> <20160812063828.GG2759@al.usersys.redhat.com> <1956404709.2011431.1470986456062.JavaMail.zimbra@redhat.com> <20160812184549-mutt-send-email-mst@kernel.org> <2113870924.2312015.1471017294088.JavaMail.zimbra@redhat.com> <20160813001158-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PULL 3/3] vhost-user: Attempt to fix a race with set_mem_table. List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Michael S. Tsirkin" Cc: Prerna Saxena , Fam Zheng , qemu-devel@nongnu.org, Peter Maydell , marcandre lureau Hi ----- Original Message ----- > On Fri, Aug 12, 2016 at 11:54:54AM -0400, Marc-Andr=C3=A9 Lureau wrote: > > Hi > >=20 > > ----- Original Message ----- > > > On Fri, Aug 12, 2016 at 03:20:56AM -0400, Marc-Andr=C3=A9 Lureau wrot= e: > > > > Hi > > > >=20 > > > > ----- Original Message ----- > > > > > sent a follow-up response to GET_FEATURES), I am now wondering if > > > > > this > > > > > patch > > > > > may break existing vhost applications too ? If so, reverting it > > > > > possibly > > > > > better. > > > > > What confuses me is why it doesn=E2=80=99t fail all the time, but= only about > > > > > 20% > > > > > to > > > > > 30% time as Fam reports. > > > > >=20 > > > > > Thoughts : Michael, Fam, MarcAndre ? > > > >=20 > > > > Indeed, I didn't ack that patch in the first place for that kind of > > > > reasons, so I would revert it. > > > >=20 > > > > thanks > > >=20 > > > I guess that's the safest thing to do for 2.7. > > > At least that's not any worse than 2.6. > > > I still think it's a good idea long term and test should be fixed, > > > but let's revert for now. > > >=20 > >=20 > > What about other backends that may have similar expectations from the > > protocol. > >=20 > > This patch is a hack, there is no reason to have it upstream. >=20 > The reason is to avoid crashes with existing backends. Which backend? I had a similar issue, it wasn't about crashes, and Prerna d= idn't mention crashes either, but anyway there is not guarantee that adding= a GET_FEATURES message will solve it... > > The solution is provided with the REPLY_ACK patch. >=20 > It needs a backend update though. >=20 > But the issue is old, it's not a regression. I think we lose nothing > by pushing the work-around out until after 2.7. >=20 > -- > MST >=20