Re: [patch 09/23] Add cmpxchg_local, cmpxchg64 and cmpxchg64_local to ia64

[Keith Owens <kaos@ocs.com.au>]

Mathieu Desnoyers (on Sun, 12 Aug 2007 10:54:43 -0400) wrote:
>Add the primitives cmpxchg_local, cmpxchg64 and cmpxchg64_local to ia64. They
>use cmpxchg_acq as underlying macro, just like the already existing ia64
>cmpxchg().
>
>Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
>CC: clameter@sgi.com
>CC: tony.luck@intel.com
>---
> include/asm-ia64/intrinsics.h |    4 ++++
> 1 file changed, 4 insertions(+)
>
>Index: linux-2.6-lttng/include/asm-ia64/intrinsics.h
>===================================================================
>--- linux-2.6-lttng.orig/include/asm-ia64/intrinsics.h	2007-07-20 18:36:09.000000000 -0400
>+++ linux-2.6-lttng/include/asm-ia64/intrinsics.h	2007-07-20 19:29:17.000000000 -0400
>@@ -158,6 +158,10 @@ extern long ia64_cmpxchg_called_with_bad
> 
> /* for compatibility with other platforms: */
> #define cmpxchg(ptr,o,n)	cmpxchg_acq(ptr,o,n)
>+#define cmpxchg_local(ptr,o,n)	cmpxchg_acq(ptr,o,n)
>+
>+#define cmpxchg64(ptr,o,n)		cmpxchg_acq(ptr,o,n)
>+#define cmpxchg64_local(ptr,o,n)	cmpxchg_acq(ptr,o,n)

As a matter of coding style, I prefer

#define cmpxchg_local	cmpxchg
#define cmpxchg64_local	cmpxchg64

Which makes it absolutely clear that they are the same code.  With your
patch, humans have to do a string compare of two defines to see if they
are the same.