Re: [PATCH] ARM: dyndbg: allow including dyndbg.h in decompressor

[Jason Baron <jbaron@akamai.com>]

On 3/10/23 9:01 AM, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> After a change to linux/module.h, dyndbg.h is now included
> indirectly from the decompressor for lz4 support, which in turn
> causes a build failure on 32-bit Arm:
> 
> In file included from include/linux/module.h:30,
>                   from arch/arm/boot/compressed/../../../../lib/lz4/lz4_decompress.c:39,
>                   from arch/arm/boot/compressed/../../../../lib/decompress_unlz4.c:10,
>                   from arch/arm/boot/compressed/decompress.c:59:
> include/linux/dynamic_debug.h: In function 'ddebug_dyndbg_module_param_cb':
> include/linux/dynamic_debug.h:307:14: error: implicit declaration of function 'strcmp' [-Werror=implicit-function-declaration]
>    307 |         if (!strcmp(param, "dyndbg")) {
>        |              ^~~~~~
> include/linux/dynamic_debug.h:1:1: note: 'strcmp' is defined in header '<string.h>'; did you forget to '#include <string.h>'?
>    +++ |+#include <string.h>
> 
> The decompressor has its own replacement for the linux/string.h contents,
> so the normal declaration is not visible here. Since the function is
> not actually called, it is sufficient to add a declaration, and this
> is in fact the correct one as it matches the definition in
> arch/arm/boot/compressed/string.c.
> 
> Fixes: 7deabd674988 ("dyndbg: use the module notifier callbacks")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> The patch that caused the problem is in linux-next, maybe fold
> the fix into that patch if possible
> ---
>   arch/arm/boot/compressed/decompress.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/arch/arm/boot/compressed/decompress.c b/arch/arm/boot/compressed/decompress.c
> index 74255e819831..0669851394f0 100644
> --- a/arch/arm/boot/compressed/decompress.c
> +++ b/arch/arm/boot/compressed/decompress.c
> @@ -31,6 +31,7 @@
>   /* Not needed, but used in some headers pulled in by decompressors */
>   extern char * strstr(const char * s1, const char *s2);
>   extern size_t strlen(const char *s);
> +extern int strcmp(const char *cs, const char *ct);
>   extern int memcmp(const void *cs, const void *ct, size_t count);
>   extern char * strchrnul(const char *, int);
>   


Hi Arnd,

Thank you for the fix up, I was about to look into this...

Acked-by: Jason Baron <jbaron@akamai.com>

Thanks,

-Jason

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