On Tue, 2015-08-25 at 13:39 -0700, Andrew Morton wrote: > On Tue, 25 Aug 2015 09:53:51 -0700 Joe Perches <[email protected]> wrote: > > commit e0e817392b9a ("CRED: Add some configurable debugging [try #6]") > > added the kdebug mechanism to this file back in 2009. > > > > The kdebug macro calls no_printk which always evaluates arguments. > > > > Most of the kdebug uses have an unnecessary call of > > atomic_read(&cred->usage) > > > > Make the kdebug macro do nothing by defining it with > > do { if (0) no_printk(...); } while (0) > > when not enabled. [] > Did you consider doing this within no_printk()?
Yes. > That would break code > which is relying on side-effects in the evaluation of a printk arg but > that's pretty weird and I bet there isn't (and won't be) such code. I'll bet you there is more than a little and I don't want to experiment with it unconditionally. All printks would need to be evaluated for that side-effect. Safer would be to create a new no_eval_printk macro and convert the no_printk uses over to that as appropriate and possibly create a CONFIG_ option to use no_eval_printk instead of no_printk/printk and let the adventurous find the side-effects. Maybe a coccinelle script can be written to find all the locations with evaluated non-constant expression arguments with side-effects. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
