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From:   Allen <allen.lkml@gmail.com>
Date:   Wed, 19 Aug 2020 16:18:16 +0530
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Subject: Re: [PATCH] block: convert tasklets to use new tasklet_setup() API
To:     Kees Cook <keescook@chromium.org>
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        Jens Axboe <axboe@kernel.dk>,
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> > > > > > > >
> > > > > > > > In preparation for unconditionally passing the
> > > > > > > > struct tasklet_struct pointer to all tasklet
> > > > > > > > callbacks, switch to using the new tasklet_setup()
> > > > > > > > and from_tasklet() to pass the tasklet pointer explicitly.
> > > > > > >
> > > > > > > Who came up with the idea to add a macro 'from_tasklet' that
> > > > > > > is just container_of? container_of in the code would be
> > > > > > > _much_ more readable, and not leave anyone guessing wtf
> > > > > > > from_tasklet is doing.
> > > > > > >
> > > > > > > I'd fix that up now before everything else goes in...
> > > > > >
> > > > > > As I mentioned in the other thread, I think this makes things
> > > > > > much more readable. It's the same thing that the timer_struct
> > > > > > conversion did (added a container_of wrapper) to avoid the
> > > > > > ever-repeating use of typeof(), long lines, etc.
> > > > >
> > > > > But then it should use a generic name, instead of each sub-system
> > > > > using some random name that makes people look up exactly what it
> > > > > does. I'm not huge fan of the container_of() redundancy, but
> > > > > adding private variants of this doesn't seem like the best way
> > > > > forward. Let's have a generic helper that does this, and use it
> > > > > everywhere.
> > > >
> > > > I'm open to suggestions, but as things stand, these kinds of
> > > > treewide
> > >
> > > On naming? Implementation is just as it stands, from_tasklet() is
> > > totally generic which is why I objected to it. from_member()? Not
> > > great with naming... But I can see this going further and then we'll
> > > suddenly have tons of these. It's not good for readability.
> >
> > Since both threads seem to have petered out, let me suggest in
> > kernel.h:
> >
> > #define cast_out(ptr, container, member) \
> >       container_of(ptr, typeof(*container), member)
> >
> > It does what you want, the argument order is the same as container_of
> > with the only difference being you name the containing structure
> > instead of having to specify its type.
>
> I like this! Shall I send this to Linus to see if this can land in -rc2
> for use going forward?
>

Cool, I shall wait for it to be accepted and then spin out V2 with cast_out()

-- 
       - Allen