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

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

[w00273186]

From: Yunjian Wang <wangyunjian@huawei.com>

"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 (obj=obj@entry=0x2) 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 (nonblocking=nonblocking@entry=0) 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 <wangyunjian@huawei.com>
---
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

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

[Marc-André Lureau]

----- Original Message -----
> From: Yunjian Wang <wangyunjian@huawei.com>
> 
> "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 (obj=obj@entry=0x2) 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 (nonblocking=nonblocking@entry=0) 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 <wangyunjian@huawei.com>

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>

> ---
> 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
> 
> 
>