Re: [PATCH 2/2] tracing/events: simplify system_enable_read()

[Andrew Morton <akpm@linux-foundation.org>]

On Fri, 08 May 2009 10:32:05 +0800
Li Zefan <lizf@cn.fujitsu.com> wrote:

> A smarter way to figure out the output of an enable file.
> 
> [ Impact: clean up ]
> 
> Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
> ---
>  kernel/trace/trace_events.c |   40 ++++++----------------------------------
>  1 files changed, 6 insertions(+), 34 deletions(-)
> 
> diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
> index 45f1099..df394bc 100644
> --- a/kernel/trace/trace_events.c
> +++ b/kernel/trace/trace_events.c
> @@ -414,10 +414,11 @@ static ssize_t
>  system_enable_read(struct file *filp, char __user *ubuf, size_t cnt,
>  		   loff_t *ppos)
>  {
> +	const char set_to_char[4] = { '?', '0', '1', 'X' };

I always worry when I see this, but gcc does manage to add the missing
`static' all by itself.  For which versions of gcc that is true I don't
know.

> +	buf[0] = set_to_char[set];

Meh.  Real men do

	buf[0] = "?01X"[set];