linux-kernel - Re: [v2] lib/string: add memrchr function

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Message-ID: <20190212191219.GB22246@kroah.com>
Date:   Tue, 12 Feb 2019 20:12:19 +0100
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Xiang Xiao <xiaoxiang781216@...il.com>
Cc:     alexander.shishkin@...ux.intel.com,
        andriy.shevchenko@...ux.intel.com, linux-kernel@...r.kernel.org,
        Xiang Xiao <xiaoxiang@...omi.com>
Subject: Re: [v2] lib/string: add memrchr function

On Wed, Feb 13, 2019 at 02:54:43AM +0800, Xiang Xiao wrote:
> Here is the detailed description for memrchr:
> 
> void *memrchr(const void *s, int c, size_t n);
> 
> The memrchr() function is like the memchr() function, except
> that it searches backward from the end of the n bytes pointed
> to by s instead of forward from the beginning.
> 
> The memrchr() functions return a pointer to the matching byte
> or NULL if the character does not occur in the given memory
> area.
> 
> Signed-off-by: Xiang Xiao <xiaoxiang@...omi.com>
> ---
>  include/linux/string.h |  1 +
>  lib/string.c           | 21 +++++++++++++++++++++
>  2 files changed, 22 insertions(+)
> 
> diff --git a/include/linux/string.h b/include/linux/string.h
> index 7927b87..f380f4b 100644
> --- a/include/linux/string.h
> +++ b/include/linux/string.h
> @@ -167,6 +167,7 @@ static inline void memcpy_flushcache(void *dst, const void *src, size_t cnt)
>  	memcpy(dst, src, cnt);
>  }
>  #endif
> +void *memrchr(const void *s, int c, size_t n);
>  void *memchr_inv(const void *s, int c, size_t n);
>  char *strreplace(char *s, char old, char new);

Also, if you really need this, why not also provide the arch-specific
versions as well?

thanks,

greg k-h