Re: [PATCH net-next] devlink: Make devlink_register to be void

Leon Romanovsky
2021-09-22T08:56:15Z

On Tue, Sep 21, 2021 at 05:39:56AM -0700, Jakub Kicinski wrote:
> On Tue, 21 Sep 2021 05:19:06 +0300 Leon Romanovsky wrote:
> > On Mon, Sep 20, 2021 at 02:04:07PM -0700, Jakub Kicinski wrote:
> > > On Mon, 20 Sep 2021 13:39:15 -0700 Jakub Kicinski wrote:
> > > > On Mon, 20 Sep 2021 17:41:44 +0300 Leon Romanovsky wrote:
> > [...]
> > > >
> > > > Unlike unused functions bringing back error handling may be
> > > > non-trivial. I'd rather you deferred such cleanups until you're
> > > > ready to post your full rework and therefore give us some confidence
> > > > the revert will not be needed.
> > >
> > > If you disagree you gotta repost, new devlink_register call got added
> > > in the meantime.
> >
> > This is exactly what I afraid, new devlink API users are added faster
> > than I can cleanup them.
> >
> > For example, let's take a look on newly added ipc_devlink_init(), it is
> > called conditionally "if (stage == IPC_MEM_EXEC_STAGE_BOOT) {". How can
> > it be different stage if we are in driver .probe() routine?
> >
> > They also introduced devlink_sio.devlink_read_pend and
> > devlink_sio.read_sem to protect from something that right position of
> > devlink_register() will fix. I also have serious doubts that their
> > current protection is correct, once they called to devlink_params_publish()
> > the user can crash the system, because he can access the parameters before
> > they initialized their protection.
> >
> > So yes, I disagree. We will need to make sure that devlink_register()
> > can't fail and it will make life easier for everyone (no need to unwind)
> > while we put that command being last in probe sequence.
>
> Remains to be seen if return type makes people follow correct ordering.

They will :)

After I'll fix all drivers that uses devlink_register :(, I'll add annotation to
all exported devlink calls will have one of three options:
1. WARN_ON(!xa_get_mark(&devlinks, devlink->index, DEVLINK_REGISTERED)) - call must be after devlink_register().
2. WARN_ON(xa_get_mark(&devlinks, devlink->index, DEVLINK_REGISTERED)) - call must be before devlink_register().
3. don't care - should be small number of such APIs and very good rationale why.
>
> > If I repost, will you take it? I don't want to waste anyone time if it
> > is not.
>
> Yeah, go for it.