Re: [PATCH] WorkStruct: Implement generic UP cmpxchg() where an arch doesn't support it

[David Howells]

Christoph Lameter <clameter@xxxxxxx> wrote:

> cmpxchg is the simplest solution to realize many other atomic operations and
> its widely available on a wide variety of platforms.

But by no means all.  Where it doesn't exist it can only be properly emulated
by something such as LL/SC if they are there.  If not, then you can't do a
safe cmpxchg on SMP.

> It is the most universal atomic instruction that I know of.

I think TAS-type things and XCHG-type things are more common.

In fact I think more things have LL/SC than have CMPXCHG.

David
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/