From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44806) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bIVc0-0002EL-Lv for qemu-devel@nongnu.org; Thu, 30 Jun 2016 02:38:09 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bIVbw-0002Za-E0 for qemu-devel@nongnu.org; Thu, 30 Jun 2016 02:38:07 -0400 Received: from mga09.intel.com ([134.134.136.24]:32647) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bIVbw-0002ZK-7a for qemu-devel@nongnu.org; Thu, 30 Jun 2016 02:38:04 -0400 Date: Thu, 30 Jun 2016 14:38:33 +0800 From: Yuanhan Liu Message-ID: <20160630063833.GG2831@yliu-dev.sh.intel.com> References: <20160624135110.17260-1-marcandre.lureau@redhat.com> <20160624135110.17260-23-marcandre.lureau@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20160624135110.17260-23-marcandre.lureau@redhat.com> Subject: Re: [Qemu-devel] [PATCH v2 22/23] vhost-user: wait until backend init is completed List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: marcandre.lureau@redhat.com Cc: qemu-devel@nongnu.org, mukawa@igel.co.jp, victork@redhat.com, jonshin@cisco.com, mst@redhat.com On Fri, Jun 24, 2016 at 03:51:09PM +0200, marcandre.lureau@redhat.com wrote: > From: Marc-André Lureau > > The chardev waits for an initial connection before starting qemu, > vhost-user wants the backend negotiation to be completed. vhost-user is > started in the net_vhost_user_event callback, which is synchronously > called after the socket is connected. > > Signed-off-by: Marc-André Lureau > --- > net/vhost-user.c | 12 +++++++++++- > 1 file changed, 11 insertions(+), 1 deletion(-) > > diff --git a/net/vhost-user.c b/net/vhost-user.c > index 95ed2d2..4badd9e 100644 > --- a/net/vhost-user.c > +++ b/net/vhost-user.c > @@ -24,6 +24,7 @@ typedef struct VhostUserState { > VHostNetState *vhost_net; > int watch; > uint64_t acked_features; > + bool started; > } VhostUserState; > > typedef struct VhostUserChardevProps { > @@ -211,6 +212,7 @@ static void net_vhost_user_event(void *opaque, int event) > return; > } > qmp_set_link(name, true, &err); > + s->started = true; > break; > case CHR_EVENT_CLOSED: > qmp_set_link(name, false, &err); > @@ -248,7 +250,15 @@ static int net_vhost_user_init(NetClientState *peer, const char *device, > s->chr = chr; > } > > - qemu_chr_add_handlers(chr, NULL, NULL, net_vhost_user_event, nc[0].name); > + do { > + Error *err = NULL; > + if (qemu_chr_wait_connected(chr, &err) < 0) { > + error_report_err(err); > + return -1; > + } > + qemu_chr_add_handlers(chr, NULL, NULL, > + net_vhost_user_event, nc[0].name); > + } while (!s->started); I haven't looked at your patchset carefully yet, but I did a quick test, and showed that above code piece just breaks vhost-user: it's a dead loop that vhost-user net will be initiated again and again. The dead loop is due to, we check "s->started" corresponding to last nc, while we set "s->started" corresponding to the first nc. --yliu