Re: [PATCH 2/7] tracing: Change strlen to sizeof for hist trigger static strings

[Joe Perches]

On Wed, 2018-12-19 at 14:16 -0600, Tom Zanussi wrote:
> 
> How's this?
> 
> [PATCH] tracing: Introduce and use strcmp_const() for hist triggers
> 
> Provide a new strcmp_const() macro and make use of it instead of the
> longer and more error-prone strncmp(str, "str", sizeof("str") - 1).
[]
> diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
[]
> @@ -22,6 +22,9 @@
>  
>  #define STR_VAR_LEN_MAX		32 /* must be multiple of sizeof(u64) */
>  
> +#define strcmp_const(str, str_const) \
> +	strncmp(str, str_const, sizeof(str_const) - 1)

Not good as it's too easy to pass a pointer as str_const
and sizeof(pointer) - 1 isn't likely the string length.