From: Tetsuya Mukawa <mukawa@igel.co.jp>
Date: Mon, 6 Jun 2016 16:44:59 +0000 (+0200)
Subject: vhost-user: add ability to know vhost-user backend disconnection
X-Git-Url: http://git.osdn.net/view?a=commitdiff_plain;h=a6553598be42e3be899acdb153fd615cd6c3eab8;p=qmiga%2Fqemu.git

vhost-user: add ability to know vhost-user backend disconnection

Current QEMU cannot detect vhost-user backend disconnection. The
patch adds ability to know it.
To know disconnection, add watcher to detect G_IO_HUP event. When
G_IO_HUP event is detected, the disconnected socket will be read
to cause a CHR_EVENT_CLOSED.

Signed-off-by: Tetsuya Mukawa <mukawa@igel.co.jp>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Tested-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Reviewed-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Reviewed-by: Victor Kaplansky <victork@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---

diff --git a/net/vhost-user.c b/net/vhost-user.c
index 1b9e73a2dc..4a7fd5fbd5 100644
--- a/net/vhost-user.c
+++ b/net/vhost-user.c
@@ -22,6 +22,7 @@ typedef struct VhostUserState {
     NetClientState nc;
     CharDriverState *chr;
     VHostNetState *vhost_net;
+    int watch;
 } VhostUserState;
 
 typedef struct VhostUserChardevProps {
@@ -167,6 +168,20 @@ static NetClientInfo net_vhost_user_info = {
         .has_ufo = vhost_user_has_ufo,
 };
 
+static gboolean net_vhost_user_watch(GIOChannel *chan, GIOCondition cond,
+                                           void *opaque)
+{
+    VhostUserState *s = opaque;
+    uint8_t buf[1];
+
+    /* We don't actually want to read anything, but CHR_EVENT_CLOSED will be
+     * raised as a side-effect of the read.
+     */
+    qemu_chr_fe_read_all(s->chr, buf, sizeof(buf));
+
+    return FALSE;
+}
+
 static void net_vhost_user_event(void *opaque, int event)
 {
     const char *name = opaque;
@@ -184,6 +199,8 @@ static void net_vhost_user_event(void *opaque, int event)
     trace_vhost_user_event(s->chr->label, event);
     switch (event) {
     case CHR_EVENT_OPENED:
+        s->watch = qemu_chr_fe_add_watch(s->chr, G_IO_HUP,
+                                         net_vhost_user_watch, s);
         if (vhost_user_start(queues, ncs) < 0) {
             exit(1);
         }
@@ -192,6 +209,8 @@ static void net_vhost_user_event(void *opaque, int event)
     case CHR_EVENT_CLOSED:
         qmp_set_link(name, false, &err);
         vhost_user_stop(queues, ncs);
+        g_source_remove(s->watch);
+        s->watch = 0;
         break;
     }