linux-kernel - Re: [PATCH 3/4] bitmap: define a cleanup function for bitmaps

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Date:   Sun, 13 Aug 2023 18:02:50 -0700
From:   Yury Norov <yury.norov@...il.com>
To:     Bartosz Golaszewski <brgl@...ev.pl>
Cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org,
        Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH 3/4] bitmap: define a cleanup function for bitmaps

On Sat, Aug 12, 2023 at 09:44:56PM +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..6709807ebb59 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 *, if (_T) bitmap_free(_T))

bitmap_free() is a wrapper around kfree(), and kfree() checks against
NULL, and returns immediately. Why this tests again?