[Qemu-devel] [PATCH v3] vhost-user: fix watcher need be removed when vhost-user hotplug

[w00273186]

From: Yunjian Wang <address@hidden>

"nc" is freed after hotplug vhost-user, but the watcher is not removed.
The QEMU crash when the watcher access the "nc" when socket disconnects.

    Program received signal SIGSEGV, Segmentation fault.
    #0  object_get_class (address@hidden) at qom/object.c:750
    #1  0x00007f9bb4180da1 in qemu_chr_fe_disconnect (be=<optimized out>) at 
chardev/char-fe.c:372
    #2  0x00007f9bb40d1100 in net_vhost_user_watch (chan=<optimized out>, 
cond=<optimized out>, opaque=<optimized out>) at net/vhost-user.c:188
    #3  0x00007f9baf97f99a in g_main_context_dispatch () from 
/usr/lib64/libglib-2.0.so.0
    #4  0x00007f9bb41d7ebc in glib_pollfds_poll () at util/main-loop.c:213
    #5  os_host_main_loop_wait (timeout=<optimized out>) at util/main-loop.c:261
    #6  main_loop_wait (address@hidden) at util/main-loop.c:515
    #7  0x00007f9bb3e266a7 in main_loop () at vl.c:1917
    #8  main (argc=<optimized out>, argv=<optimized out>, envp=<optimized out>) 
at vl.c:4786

Signed-off-by: Yunjian Wang <address@hidden>
---
v3:
 -fix conflicts with current master.

v2:
 -move the chunk before deinit.

ps:
 reproduce steps:
    1. virsh attach-device vm0 vhost-user.xml
    2. virsh detach-device vm0 vhost-user.xml
    3. virsh attach-device vm0 vhost-user.xml
    4. service openvswitch restart
    5. repeat step 2~4

 the vhost-user xml:
    <interface type='vhostuser'>
      <mac address='00:01:01:00:10:41'/>
      <source type='unix' path='/var/run/vhost-user/tap1' mode='client'/>
      <model type='virtio'/>
      <driver queues='8'/>
    </interface>
---
 net/vhost-user.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/vhost-user.c b/net/vhost-user.c
index 36f32a2..c23927c 100644
--- a/net/vhost-user.c
+++ b/net/vhost-user.c
@@ -151,6 +151,10 @@ static void vhost_user_cleanup(NetClientState *nc)
         s->vhost_net = NULL;
     }
     if (nc->queue_index == 0) {
+        if (s->watch) {
+            g_source_remove(s->watch);
+            s->watch = 0;
+        }
         qemu_chr_fe_deinit(&s->chr, true);
     }
 
-- 
1.8.3.1