From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50282) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dXSEF-0008Pf-I3 for qemu-devel@nongnu.org; Tue, 18 Jul 2017 09:07:56 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dXSEA-0007y2-Ph for qemu-devel@nongnu.org; Tue, 18 Jul 2017 09:07:55 -0400 Received: from mx1.redhat.com ([209.132.183.28]:33488) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dXSEA-0007xm-GZ for qemu-devel@nongnu.org; Tue, 18 Jul 2017 09:07:50 -0400 References: <20170621132340.27686-1-kraxel@redhat.com> <20170621132340.27686-6-kraxel@redhat.com> From: Laurent Vivier Message-ID: Date: Tue, 18 Jul 2017 15:07:39 +0200 MIME-Version: 1.0 In-Reply-To: <20170621132340.27686-6-kraxel@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PULL 5/6] console: remove do_safe_dpy_refresh List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Gerd Hoffmann , qemu-devel@nongnu.org Cc: =?UTF-8?Q?Alex_Benn=c3=a9e?= , Peter Maydell On 21/06/2017 15:23, Gerd Hoffmann wrote: > Drop the temporary workaround for the broken display updates. > All display adapters are updated, so this should be safe without > causing regressions. It seems it breaks QMP command 'migrate "exec:cat>mig"'. The command hangs and doesn't create the file. It happens with qemu-system-ppc64 on x86 (so TCG mode). my command: ./ppc64-softmmu/qemu-system-ppc64 -serial mon:stdio I wait SLOF fails to find an OS, and: Ctrl-a c (qemu) migrate -d "exec:cat>mig" The file is not created and the command hangs: #0 in __lll_lock_wait #1 in pthread_mutex_lock #2 in qemu_mutex_lock #3 in rcu_init_lock #4 in fork #5 in qemu_fork #6 in qio_channel_command_new_spawn #7 in exec_start_outgoing_migration #8 in qmp_migrate ... It looks like a deadlock. Laurent > Signed-off-by: Gerd Hoffmann > Acked-by: Alex Benn=C3=A9e > Message-id: 20170614084538.32480-1-kraxel@redhat.com > --- > ui/console.c | 25 +------------------------ > 1 file changed, 1 insertion(+), 24 deletions(-) >=20 > diff --git a/ui/console.c b/ui/console.c > index d914cced53..af0c56c600 100644 > --- a/ui/console.c > +++ b/ui/console.c > @@ -1579,36 +1579,13 @@ bool dpy_gfx_check_format(QemuConsole *con, > return true; > } > =20 > -/* > - * Safe DPY refresh for TCG guests. We use the exclusive mechanism to > - * ensure the TCG vCPUs are quiescent so we can avoid races between > - * dirty page tracking for direct frame-buffer access by the guest. > - * > - * This is a temporary stopgap until we've fixed the dirty tracking > - * races in display adapters. > - */ > -static void do_safe_dpy_refresh(DisplayChangeListener *dcl) > -{ > - qemu_mutex_unlock_iothread(); > - start_exclusive(); > - qemu_mutex_lock_iothread(); > - dcl->ops->dpy_refresh(dcl); > - qemu_mutex_unlock_iothread(); > - end_exclusive(); > - qemu_mutex_lock_iothread(); > -} > - > static void dpy_refresh(DisplayState *s) > { > DisplayChangeListener *dcl; > =20 > QLIST_FOREACH(dcl, &s->listeners, next) { > if (dcl->ops->dpy_refresh) { > - if (tcg_enabled()) { > - do_safe_dpy_refresh(dcl); > - } else { > - dcl->ops->dpy_refresh(dcl); > - } > + dcl->ops->dpy_refresh(dcl); > } > } > } >=20