linux-kernel - Re: [PATCH RFC] x86, boot: add missing declaration of string functions

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Date:   Thu, 5 Jan 2017 09:02:09 +0100
From:   Ingo Molnar <mingo@...nel.org>
To:     Nicholas Mc Guire <hofrat@...dl.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFC] x86, boot: add missing declaration of string
 functions


* Nicholas Mc Guire <hofrat@...dl.org> wrote:

> Add the missing declarations of basic string functions to string.h to allow
> a clean build.
> 
> Fixes: commit 5be865661516 ("String-handling functions for the new x86 setup code.")
> Signed-off-by: Nicholas Mc Guire <hofrat@...dl.org>
> ---
> 
> sparse issues a set of warnings about missing declarations:
> arch/x86/purgatory/../boot/string.c:18:5: warning: symbol 'memcmp' was not declared. Should it be static?
> arch/x86/purgatory/../boot/string.c:26:5: warning: symbol 'strcmp' was not declared. Should it be static?
> arch/x86/purgatory/../boot/string.c:42:5: warning: symbol 'strncmp' was not declared. Should it be static?
> arch/x86/purgatory/../boot/string.c:58:8: warning: symbol 'strnlen' was not declared. Should it be static?
> arch/x86/purgatory/../boot/string.c:69:14: warning: symbol 'atou' was not declared. Should it be static?
> arch/x86/purgatory/../boot/string.c:99:20: warning: symbol 'simple_strtoull' was not declared. Should it be static?
> arch/x86/purgatory/../boot/string.c:128:8: warning: symbol 'strlen' was not declared. Should it be static?
> arch/x86/purgatory/../boot/string.c:142:6: warning: symbol 'strstr' was not declared. Should it be static?
> 
> This patch has one checkpatch warning about the use of simple_strtoul which
> is obsolete. As this is an independent implementation it is not clear if
> the changes made in simple_strtoul -> _kstrtoull might also need to be
> applied here ?
> 
> Patch was compile tested with: x86_64_defconfig
> 
> Patch is against 4.9.0 (localversion-next is next-20161223)
> 
>  arch/x86/boot/string.c |  1 +
>  arch/x86/boot/string.h |  9 +++++++++
>  2 files changed, 10 insertions(+)
> 
> diff --git a/arch/x86/boot/string.c b/arch/x86/boot/string.c
> index cc3bd58..9e240fc 100644
> --- a/arch/x86/boot/string.c
> +++ b/arch/x86/boot/string.c
> @@ -14,6 +14,7 @@
>  
>  #include <linux/types.h>
>  #include "ctype.h"
> +#include "string.h"
>  
>  int memcmp(const void *s1, const void *s2, size_t len)
>  {
> diff --git a/arch/x86/boot/string.h b/arch/x86/boot/string.h
> index 725e820..f6ee139 100644
> --- a/arch/x86/boot/string.h
> +++ b/arch/x86/boot/string.h
> @@ -18,4 +18,13 @@ int memcmp(const void *s1, const void *s2, size_t len);
>  #define memset(d,c,l) __builtin_memset(d,c,l)
>  #define memcmp	__builtin_memcmp
>  
> +int strcmp(const char *str1, const char *str2);
> +int strncmp(const char *cs, const char *ct, size_t count);
> +size_t strlen(const char *s);
> +char *strstr(const char *s1, const char *s2);
> +size_t strnlen(const char *s, size_t maxlen);
> +unsigned int atou(const char *s);
> +unsigned long long simple_strtoull(const char *cp,
> +				    char **endp, unsigned int base);

Looks good to me, but please also mark them 'extern' to highlight the API 
declarations like the rest of the kernel does - such as kernel.h which has
the kernel's simple_strtoull() declaration, etc.

It's not required syntactically, but it's a good stylistic principle to keep 
external APIs organized.

Thanks,

	Ingo