Re: better patch for linux/bitops.h

From: Sandy Harris
Date: Thu May 05 2016 - 17:34:59 EST

On Wed, May 4, 2016 at 11:50 PM, Theodore Ts'o <tytso@xxxxxxx> wrote:

> Instead of arguing over who's "sane" or "insane", can we come up with
> a agreed upon set of tests, and a set of compiler and compiler
> versions ...

I completely fail to see why tests or compiler versions should be
part of the discussion. The C standard says the behaviour in
certain cases is undefined, so a standard-compliant compiler
can generate more-or-less any code there.

As long as any of portability, reliability or security are among our
goals, any code that can give undefined behaviour should be
considered problematic.

> But instead of arguing over what works and doesn't, let's just create
> the the test set and just try it on a wide range of compilers and
> architectures, hmmm?

No. Let's just fix the code so that undefined behaviour cannot occur.

Creating test cases for a fix and trying them on a range of systems
would be useful, perhaps essential, work. Doing tests without a fix
would be a complete waste of time.