Re: spinlock assertion macros

From: Sandy Harris (pashley@storm.ca)
Date: Thu Jul 11 2002 - 18:52:45 EST


Oliver Xymoron wrote:
>
> On Thu, 11 Jul 2002, Daniel Phillips wrote:
>
> > I was thinking of something as simple as:
> >
> > #define spin_assert_locked(LOCK) BUG_ON(!spin_is_locked(LOCK))
> >
> > but in truth I'd be happy regardless of the internal implementation. A note
> > on names: Linus likes to shout the names of his BUG macros. I've never been
> > one for shouting, but it's not my kernel, and anyway, I'm happy he now likes
> > asserts. I bet he'd like it more spelled like this though:
> >
> > MUST_HOLD(&lock);
>
> I prefer that form too.

Is it worth adding MUST_NOT_HOLD(&lock) in an attempt to catch potential
deadlocks?

Say that if two or more of locks A, B and C are to be taken, then
they must be taken in that order. You might then have code like:

        MUST_NOT_HOLD(&lock_B) ;
        MUST_NOT_HOLD(&lock_C) ;
        spinlock(&lock_A) ;

I think you need a separate asertion for this !MUST_NOT_HOLD(&lock)
has different semantics.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/



This archive was generated by hypermail 2b29 : Mon Jul 15 2002 - 22:00:21 EST