On Thu, May 21, 2009 at 09:27:29PM -0700, Joe Perches wrote:
> The printk_once macro in kernel.h is limited to printk
>
> This generalizes the functionality of printk_once and
> allows statements like DO_ONCE(pr_info("foo\n"))
> and DO_ONCE(initialize(foo));
Sigh... Please, don't do introduce new control structures without extremely
good reasons.
printk_once() has syntax of function call; it's far more tolerable for
casual reader (e.g. somebody looking through the code while trying to
localize a bug) since it doesn't interrupt the flow - it parses as
"some function call, apparently doing some debugging output, let's see
if there are any obvious side effects in the arguments and move on".
Your DO_ONCE(....) parses as "what the fuck is that?" followed by
grepping for definition, and the cost is much higher.
Don't do that. Staying close to normal syntax is a very good thing;
preprocessor can be used in a lot of ways that are harmful and introduction
of (effectively) new kinds of statements is a prime example. It *does*
have its place, but it should be done very sparingly.
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