Re: [PATCH v12 01/16] tracing: Use str_has_prefix() in synth_event_create()

[Joe Perches]

On Tue, 2019-01-15 at 16:05 -0600, Tom Zanussi wrote:
> Since we now have a str_has_prefix() that returns the length, we can
> use that instead of explicitly calculating it.
[]
> diff --git a/kernel/trace/trace_events_hist.c 
> b/kernel/trace/trace_events_hist.c
[]
> @@ -1200,8 +1200,7 @@ static int synth_event_create(int argc, const char 
> **argv)
>  
>       /* This interface accepts group name prefix */
>       if (strchr(name, '/')) {
> -             len = sizeof(SYNTH_SYSTEM "/") - 1;
> -             if (strncmp(name, SYNTH_SYSTEM "/", len))
> +             if ((len = str_has_prefix(name, SYNTH_SYSTEM "/")) == 0)

Since this is a single test, and not multiple if/else if
blocks, I believe this would read better on two lines

                len = str_has_prefix(name, SYNTH_SYSTEM "/");
                if (len == 0)

>                       return -EINVAL;
>               name += len;
>       }