Hi Peter,
On Tue, May 31, 2016 at 12:19 PM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
Implement FETCH-OP atomic primitives, these are very similar to the
existing OP-RETURN primitives we already have, except they return the
value of the atomic variable _before_ modification.
This is especially useful for irreversible operations -- such as
bitops (because it becomes impossible to reconstruct the state prior
to modification).
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
---
arch/m68k/include/asm/atomic.h | 53 +++++++++++++++++++++++++++++++++++++----
1 file changed, 49 insertions(+), 4 deletions(-)
--- a/arch/m68k/include/asm/atomic.h
+++ b/arch/m68k/include/asm/atomic.h
@@ -38,6 +38,13 @@ static inline void atomic_##op(int i, at
#ifdef CONFIG_RMW_INSNS
+/*
+ * Am I reading these CAS loops right in that %2 is the old value and the first
+ * iteration uses an uninitialized value?
+ *
+ * Would it not make sense to add: tmp = atomic_read(v); to avoid this?
+ */
+
#define ATOMIC_OP_RETURN(op, c_op, asm_op) \
static inline int atomic_##op##_return(int i, atomic_t *v) \
{ \
Do we want the above comment in the code?
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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