linux-kernel - Re: [PATCH v1 1/1] bitops: Share BYTES_TO

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Message-ID: <a5574786-0a49-454d-67e3-571983e6a6e8@intel.com>
Date:   Fri, 25 Aug 2023 16:49:07 +0200
From:   Alexander Lobakin <aleksander.lobakin@...el.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
CC:     Yury Norov <yury.norov@...il.com>, Uros Bizjak <ubizjak@...il.com>,
        "Masami Hiramatsu (Google)" <mhiramat@...nel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-trace-kernel@...r.kernel.org>,
        "Steven Rostedt" <rostedt@...dmis.org>
Subject: Re: [PATCH v1 1/1] bitops: Share BYTES_TO_BITS() for everyone

From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Date: Thu, 24 Aug 2023 15:37:28 +0300

> It may be new callers for the same macro, share it.
> 
> Note, it's unknown why it's represented in the current form instead of
> simple multiplication and commit 1ff511e35ed8 ("tracing/kprobes: Add
> bitfield type") doesn't explain that neither. Let leave it as is and
> we may improve it in the future.

Maybe symmetrical change in tools/ like I did[0] an aeon ago?

> 
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
>  include/linux/bitops.h     | 2 ++
>  kernel/trace/trace_probe.c | 3 +--
>  2 files changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/bitops.h b/include/linux/bitops.h
> index 2ba557e067fe..66dc091e0c28 100644
> --- a/include/linux/bitops.h
> +++ b/include/linux/bitops.h
> @@ -21,6 +21,8 @@
>  #define BITS_TO_U32(nr)		__KERNEL_DIV_ROUND_UP(nr, BITS_PER_TYPE(u32))
>  #define BITS_TO_BYTES(nr)	__KERNEL_DIV_ROUND_UP(nr, BITS_PER_TYPE(char))
>  
> +#define BYTES_TO_BITS(nb)	((BITS_PER_LONG * (nb)) / sizeof(long))
> +
>  extern unsigned int __sw_hweight8(unsigned int w);
>  extern unsigned int __sw_hweight16(unsigned int w);
>  extern unsigned int __sw_hweight32(unsigned int w);
> diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
> index c68a72707852..da6297d24d61 100644
> --- a/kernel/trace/trace_probe.c
> +++ b/kernel/trace/trace_probe.c
> @@ -11,6 +11,7 @@
>   */
>  #define pr_fmt(fmt)	"trace_probe: " fmt
>  
> +#include <linux/bitops.h>
>  #include <linux/bpf.h>
>  
>  #include "trace_probe.h"
> @@ -830,8 +831,6 @@ parse_probe_arg(char *arg, const struct fetch_type *type,
>  	return ret;
>  }
>  
> -#define BYTES_TO_BITS(nb)	((BITS_PER_LONG * (nb)) / sizeof(long))
> -
>  /* Bitfield type needs to be parsed into a fetch function */
>  static int __parse_bitfield_probe_arg(const char *bf,
>  				      const struct fetch_type *t,

[0]
https://github.com/alobakin/linux/commit/fd308001fe6d38837fe820427209a6a99e4850a8

Thanks,
Olek