linux-kernel - Re: [PATCH 1/4] bitmap: define a cleanup function for bitmaps

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Date:   Tue, 12 Sep 2023 16:28:21 +0200
From:   Bartosz Golaszewski <brgl@...ev.pl>
To:     Yury Norov <yury.norov@...il.com>
Cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Thomas Gleixner <tglx@...utronix.de>,
        Marc Zyngier <marc.zyngier@....com>,
        linux-kernel@...r.kernel.org,
        Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH 1/4] bitmap: define a cleanup function for bitmaps

On Tue, Sep 12, 2023 at 3:43 PM Yury Norov <yury.norov@...il.com> wrote:
>
> On Tue, Sep 12, 2023 at 10:55:38AM +0200, Bartosz Golaszewski wrote:
> > From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> >
> > Add support for autopointers for bitmaps allocated with bitmap_alloc()
> > et al.
> >
> > Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> > ---
> >  include/linux/bitmap.h | 3 +++
> >  1 file changed, 3 insertions(+)
> >
> > diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
> > index 03644237e1ef..ba8c0d733842 100644
> > --- a/include/linux/bitmap.h
> > +++ b/include/linux/bitmap.h
> > @@ -6,6 +6,7 @@
> >
> >  #include <linux/align.h>
> >  #include <linux/bitops.h>
> > +#include <linux/cleanup.h>
> >  #include <linux/find.h>
> >  #include <linux/limits.h>
> >  #include <linux/string.h>
> > @@ -125,6 +126,8 @@ unsigned long *bitmap_alloc_node(unsigned int nbits, gfp_t flags, int node);
> >  unsigned long *bitmap_zalloc_node(unsigned int nbits, gfp_t flags, int node);
> >  void bitmap_free(const unsigned long *bitmap);
> >
> > +DEFINE_FREE(bitmap, unsigned long *, bitmap_free(_T))
>
> So now it doesn't do weird  "if (_T) bitmap_free(_T)". Have you got any
> feedback from Peter for that?
>

I did get feedback from Peter. Unfortunately it was right *after* I
sent this. Turns out the NULL-pointer check is there for a reason,
please see the comment in this patch:
https://lore.kernel.org/all/169451499208.27769.5856056754166699857.tip-bot2@tip-bot2/T/#u

That means I will have to resend this one.

Bart

> My point is that if the above is correct, all the following
> declarations need to be revisited:
>
> yury:linux$ git grep DEFINE_FREE|grep if
> include/linux/cleanup.h:25: * DEFINE_FREE(kfree, void *, if (_T) kfree(_T))
> include/linux/device.h:1058:DEFINE_FREE(device_del, struct device *, if (_T) device_del(_T))
> include/linux/device.h:1228:DEFINE_FREE(put_device, struct device *, if (_T) put_device(_T))
> include/linux/mutex.h:224:DEFINE_FREE(mutex, struct mutex *, if (_T) mutex_unlock(_T))
> include/linux/rwsem.h:208:DEFINE_FREE(up_read, struct rw_semaphore *, if (_T) up_read(_T))
> include/linux/rwsem.h:209:DEFINE_FREE(up_write, struct rw_semaphore *, if (_T) up_write(_T))
> include/linux/sched/task.h:164:DEFINE_FREE(put_task, struct task_struct *, if (_T) put_task_struct(_T))
> include/linux/slab.h:231:DEFINE_FREE(kfree, void *, if (_T) kfree(_T))
>
> For the patch:
> Acked-by: Yury Norov <yury.norov@...il.com>