On 7/10/2015 6:39 AM, Peter Zijlstra wrote:

On Fri, Jul 10, 2015 at 11:10:33AM +0200, Geert Uytterhoeven wrote:

quoted

Hi Peter,

On Thu, Jul 9, 2015 at 7:29 PM, Peter Zijlstra [off-list ref] wrote:

quoted

--- a/include/linux/atomic.h
+++ b/include/linux/atomic.h

@@ -28,6 +28,23 @@ static inline int atomic_add_unless(atom
  #define atomic_inc_not_zero(v)         atomic_add_unless((v), 1, 0)
  #endif

+#ifndef atomic_nand
+static inline void atomic_nand(int i, atomic_t *v)
+{
+       atomic_and(~i, v);

That sounds like a misnomer...

Your NAND is "A & ~B", while my[*] NAND is "~(A & B)"?

[*] https://en.wikipedia.org/wiki/NAND_logic

Right you are.

quoted

What about atomic_clear()? (Is atomic_bic() too ARM-centric?)

atomic_and_not() ?

I've seen this as ANDN (as opposed to NAND).  That's the name I used in
the tilepro atomics as the thing that implements the bitmask clear operation.
SPARC also has an "andn" instruction with this semantics.

-- 
Chris Metcalf, EZChip Semiconductor
http://www.ezchip.com