Re: [External] Re: [RFC 3/4] vduse: grab the module's references until there is no vduse device

[谢永吉 <xieyongji@bytedance.com>]

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On Mon, Oct 19, 2020 at 11:05 PM Michael S. Tsirkin <mst@redhat.com> wrote:

> On Mon, Oct 19, 2020 at 10:56:22PM +0800, Xie Yongji wrote:
> > The module should not be unloaded if any vduse device exists.
> > So increase the module's reference count when creating vduse
> > device. And the reference count is kept until the device is
> > destroyed.
> >
> > Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
> > ---
> >  drivers/vdpa/vdpa_user/vduse_dev.c | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c
> b/drivers/vdpa/vdpa_user/vduse_dev.c
> > index 6787ba66725c..f04aa02de8c1 100644
> > --- a/drivers/vdpa/vdpa_user/vduse_dev.c
> > +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> > @@ -887,6 +887,7 @@ static int vduse_destroy_dev(u32 id)
> >       kfree(dev->vqs);
> >       vduse_iova_domain_destroy(dev->domain);
> >       vduse_dev_destroy(dev);
> > +     module_put(THIS_MODULE);
> >
> >       return 0;
> >  }
> > @@ -931,6 +932,7 @@ static int vduse_create_dev(struct vduse_dev_config
> *config)
> >
> >       dev->connected = true;
> >       list_add(&dev->list, &vduse_devs);
> > +     __module_get(THIS_MODULE);
> >
> >       return fd;
> >  err_fd:
>
> This kind of thing is usually an indicator of a bug. E.g.
> if the refcount drops to 0 on module_put(THIS_MODULE) it
> will be unloaded and the following return will not run.
>
>
Should this happen?  The refcount should be only decreased to 0 after the
misc_device is closed?

Thanks,
Yongji

>
>

> > --
> > 2.25.1
>
>

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