Re: module: Ensure a module's state is set accordingly during module coming cleanup code

[Jessica Yu]

+++ Miroslav Benes [16/11/16 16:49 +0100]:
> On Wed, 9 Nov 2016, Jessica Yu wrote:
>
> > +++ Rusty Russell [26/10/16 11:24 +1030]:
> > > Aaron Tomlin <atomlin@xxxxxxxxxx> writes:
> > > > In load_module() in the event of an error, for e.g. unknown module
> > > > parameter(s) specified we go to perform some module coming clean up
> > > > operations. At this point the module is still in a "formed" state
> > > > when it is actually going away.
> > > >
> > > > This patch updates the module's state accordingly to ensure anyone on the
> > > > module_notify_list waiting for a module going away notification will be
> > > > notified accordingly.
> > >
> > > I recall a similar proposal before.
> > >
> > > I've audited all the subscribers to check they didn't look at
> > > mod->state; they seem OK.
> > >
> > > We actually do this in the init-failed path, so this should be OK.
> >
> > We did discuss a similar proposal before:
> >
> >    https://lkml.kernel.org/r/87a8m7ko6j.fsf@xxxxxxxxxxxxxxx
> >
> > The complaint back then was that we need to be in the COMING state for
> > strong_try_module_get() to fail. But it will also correctly fail for GOING
> > modules in the module_is_live() check in the subsequent call to
> > try_module_get(), so I believe we are still OK here.
>
> FWIW, I looked and this is true. Even the error -ENOENT could be better in
> this case than -EBUSY (since the module is going away).
>
> Reviewed-by: Miroslav Benes <mbenes@xxxxxxx>
>
> for the patch, if you want it.
>
> Anyway, the comment above strong_try_module_get() is not true for almost 9
> nine years. So how about something like:
>
> -->8--
>
> From 872e11394fdaba8fb9a333e114dc92273d2d1bf5 Mon Sep 17 00:00:00 2001
> From: Miroslav Benes <mbenes@xxxxxxx>
> Date: Wed, 16 Nov 2016 16:45:48 +0100
> Subject: [PATCH] module: Fix a comment above strong_try_module_get()
>
> The comment above strong_try_module_get() function is not true anymore.
> Return values changed with commit c9a3ba55bb5d ("module: wait for
> dependent modules doing init.").
>
> Signed-off-by: Miroslav Benes <mbenes@xxxxxxx>

Thanks Miroslav, that comment was confusing and needed updating. I've
queued this on top of the other patches.

Jessica