Hi Norwitz ，
Thanks for your good suggestion.
I got this fix from net/vhost-user.c, it has the same issue with this case.
Your suggestion is a good option.
I'm trying to do some work. but there is another crash issue ...
I need some time to make your idea be workable.
This is the net/vhost-user patch:
commit e7c83a885f865128ae3cf1946f8cb538b63cbfba
Author: Marc-André Lureau <marcandre.lur...@redhat.com>
Date: Mon Feb 27 14:49:56 2017 +0400
vhost-user: delay vhost_user_stop
Since commit b0a335e351103bf92f3f9d0bd5759311be8156ac, a socket write
may trigger a disconnect events, calling vhost_user_stop() and clearing
all the vhost_dev strutures holding data that vhost.c functions expect
to remain valid. Delay the cleanup to keep the vhost_dev structure
valid during the vhost.c functions.
Feng Li
Raphael Norwitz <raphael.norw...@nutanix.com> 于2020年4月17日周五 上午11:41写道：
>
> On Wed, Apr 15, 2020 at 11:28:23AM +0800, Li Feng wrote:
> >
> > switch (event) {
> > case CHR_EVENT_OPENED:
> > @@ -363,7 +376,16 @@ static void vhost_user_blk_event(void *opaque,
> > QEMUChrEvent event)
> > }
> > break;
> > case CHR_EVENT_CLOSED:
> > - vhost_user_blk_disconnect(dev);
> > + /*
> > + * a close event may happen during a read/write, but vhost
> > + * code assumes the vhost_dev remains setup, so delay the
> > + * stop & clear to idle.
> > + */
> > + ctx = qemu_get_current_aio_context();
> > +
> > + qemu_chr_fe_set_handlers(&s->chardev, NULL, NULL, NULL,
> > + NULL, NULL, NULL, false);
> > + aio_bh_schedule_oneshot(ctx, vhost_user_blk_chr_closed_bh, opaque);
>
> This seems a bit racy. What’s to stop the async operation from executing
> before
> the next read?
>
> If the issue is just that the vhost_dev state is being destroyed too early,
> why
> don’t we rather move the vhost_dev_cleanup() call from
> vhost_user_blk_disconnect()
> to vhost_user_blk_connect()? We may need to add some state to tell if this is
> the
> first connect or a reconnect so we don’t call vhost_dev_cleanup() on initial
> connect, but as long as we call vhost_dev_cleanup() before vhost_dev_init()
> every time the device reconnects it shouldn’t matter that we keep that state
> around.
>
> Thoughts?
>
> > break;
> > case CHR_EVENT_BREAK:
> > case CHR_EVENT_MUX_IN:
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