On Sat, Dec 15, 2007 at 02:52:11PM +0800, Herbert Xu wrote: > On Sat, Dec 15, 2007 at 02:04:49PM +0800, Herbert Xu wrote: > > > > I suppose we'll have to either introduce a new primitive or just > > go back to using BUG_ON. > > Let's do the conservative thing and add a new primitive. > > [PATCH] Added BARF_ON/BARF_ON_ONCE > > The description of CONFIG_BUG clearly states that both BUG and > WARN_ON may be skipped. However, our actual implementation still > checks the condition on WARN_ON if it's used as part of an if > statement or such. > > I tried to compile it away but Matt Mackall pointed out that > people may already be using it in ways that were not intended. > In particular, it may have been used for conditions that are > thought to be possible. > > So this patch adds a new pair of macros BARF_ON and BARF_ON_ONCE > that are clearly marked as such to prevent abuse. The intended > usage model is identical to WARN_ON except that they should only > be used for conditions that are thought to be impossible. In > other words, only use them to replace BUG_ON's that may be called > by an IRQ handler or within locks.
Egads, this just makes the whole bad BUG_ON vs WARN_ON situation worse. This adds yet another non-distinction, because the difference between BUG_ON and WARN_ON has absolutely nothing to do with the (perceived or actual) probability of the condition. We've got plenty of evidence that BUG_ON and WARN_ON conditions -do- happen. So choosing between BUG_ON and WARN_ON is choosing whether a box should be forcibly killed or not and nothing more. You've clearly got a use-case in mind where WARN_ON + !CONFIG_BUG isn't doing what you want, please share it with us. -- Mathematics is the supreme nostalgia of our time. -- 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/
