Messages in this thread | | | From | "Stefan Monnier" <monnier+lists/linux/kernel/news/@tequila.cs.yale.edu> | Subject | Re: [PATCH] *(int*)0 = 0 & variations | Date | 24 Jun 1999 14:06:12 -0400 |
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>>>>> "Jeff" == Jeff Garzik <jgarzik@pobox.com> writes: > AC posted in this thread, saying that assert code already exists in the > kernel, in the networking code (grep for BUG_TRAP). Guess what? It > evaluates to null. In fact, grepping around, every assert macro I could > find in the kernel (not many, granted) evaluates to null in its > non-debug form.
I completely agree. The only reason why people want the expr to be evaluated in the no-debug case is that some broken kasserts might have side effects. This argument is specious: fix the asserts. One way to make such broken asserts a bit easier to find is to do something like
#define kassert(cond) \ if ((cond) && ((cond) == (cond))) {} else {burp}
It doesn't catch all cases, far from that, but has the advantage of only slowing down the debug case. There could be several kassert behaviors (even changeable at run time):
- default: just do the check and print any error - no debug: replace kassert with (void)0 - debug asserts: use the multiple-eval trick above to increase the chances of catching buggy asserts.
and orthogonal to that, you could choose whether to oops/panic/donothing in case of an actual failure.
Stefan
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