netdev - Re: [PATCH] net/ncsi: Fix re-registering ncsi device

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Message-ID: <CACPK8Xf2aR8wXOQK4byj_UOQUqvd8uMVTBh8UMKZn8uT6cqdOQ@mail.gmail.com>
Date:   Thu, 12 Nov 2020 01:30:43 +0000
From:   Joel Stanley <joel@....id.au>
To:     Jakub Kicinski <kuba@...nel.org>
Cc:     Samuel Mendoza-Jonas <sam@...dozajonas.com>,
        "David S . Miller" <davem@...emloft.net>,
        Andrew Jeffery <andrew@...id.au>,
        Networking <netdev@...r.kernel.org>
Subject: Re: [PATCH] net/ncsi: Fix re-registering ncsi device

On Thu, 12 Nov 2020 at 01:20, Jakub Kicinski <kuba@...nel.org> wrote:
>
> On Thu, 12 Nov 2020 01:11:04 +0000 Joel Stanley wrote:
> > On Thu, 12 Nov 2020 at 00:57, Jakub Kicinski <kuba@...nel.org> wrote:
> > >
> > > On Thu, 12 Nov 2020 11:10:21 +1030 Joel Stanley wrote:
> > > > If a user unbinds and re-binds a ncsi aware driver, the kernel will
> > > > attempt to register the netlink interface at runtime. The structure is
> > > > marked __ro_after_init so this fails at this point.
> > >
> > > netlink family should be registered at module init and unregistered at
> > > unload. That's a better fix IMO.
> >
> > I don't follow, isn't that what is implemented already?
> >
> > Perhaps I'm getting confused because the systems that use this code
> > build the drivers in. The bug I'm seeing is when we unbind and re-bind
> > the driver without any module loading or unloading.
>
> It's registered from ncsi_register_dev(), which is obviously broken,
> because there is only one family so it would never work if there was
> more than one ncsi netdev.
>
> Looks like NCSI can only be built in, so instead of module init it
> should be a subsys_initcall().
>
> Basically remove ncsi_unregister_netlink(), remove the dev parameter
> from ncsi_init_netlink() and add:
>
> subsys_initcall(ncsi_init_netlink);
>
> at the end of ncsi-netlink.c

Thanks for the explanation, I'll do that.