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

[Marc-André Lureau]

On Sat, Jul 22, 2017 at 2:35 AM Michael S. Tsirkin <address@hidden> wrote:

> On Fri, Jul 21, 2017 at 11:19:04AM +0000, Marc-André Lureau wrote:
> > Hi
> >
> > On Fri, Jul 21, 2017 at 7:18 AM w00273186 <address@hidden>
> wrote:
> >
> >     From: Yunjian Wang <address@hidden>
> >
> >     "nc" is freed after hotplug vhost-user, but the watcher don't be
> removed.
> >     The QEMU crash when the watcher access the "nc" on socket disconnect.
> >
> >
> >
> > This is actually your 3rd iteration on the patch
> >
> > Could your describe your changes since:
> > "[PATCH v2] vhost-user: fix watcher need be removed when vhost-user
> hotplug"
> >
> > Thanks
>
> Yes but it's a 3-liner. That's way below the limit where you need
> detailed change history. Does the patch make sense to you?
>
>
That's not all, the fact that he didn't come up with the same solution in
the first place, and I didn't notice a problem either with the previous
approach is enough to ask from some clarification on which approach is
best, and I bet there is something to say.

Furthermore, we would really benefit from having repeatable cases for this
kind of fixes.



> >
> >         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>
> >     ---
> >      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
> >
> >
> >
> >
> > --
> > Marc-André Lureau
>
-- 
Marc-André Lureau