[PATCH 03/26] locking/atomic: hexagon: remove redundant arch_atomic_cmpxchg

Mark Rutland
2023-05-22T12:27:12Z

Hexagon's implementation of arch_atomic_cmpxchg() is identical to its
implementation of arch_cmpxchg(). Have it define arch_atomic_cmpxchg()
in terms of arch_cmpxchg(), matching what it does for arch_atomic_xchg()
and arch_xchg().

At the same time, remove the kerneldoc comments for hexagon's
arch_atomic_xchg() and arch_atomic_cmpxchg(). The arch_atomic_*()
namespace is shared by all architectures and the API should be
documented centrally, and the comments aren't all that helpful as-is.

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
---
arch/hexagon/include/asm/atomic.h | 46 +++----------------------------
1 file changed, 4 insertions(+), 42 deletions(-)

diff --git a/arch/hexagon/include/asm/atomic.h b/arch/hexagon/include/asm/atomic.h
index 6e94f8d04146f..738857e10d6ec 100644
--- a/arch/hexagon/include/asm/atomic.h
+++ b/arch/hexagon/include/asm/atomic.h
@@ -36,49 +36,11 @@ static inline void arch_atomic_set(atomic_t *v, int new)
*/
#define arch_atomic_read(v) READ_ONCE((v)->counter)

-/**
- * arch_atomic_xchg - atomic
- * @v: pointer to memory to change
- * @new: new value (technically passed in a register -- see xchg)
- */
-#define arch_atomic_xchg(v, new) (arch_xchg(&((v)->counter), (new)))
-
-
-/**
- * arch_atomic_cmpxchg - atomic compare-and-exchange values
- * @v: pointer to value to change
- * @old: desired old value to match
- * @new: new value to put in
- *
- * Parameters are then pointer, value-in-register, value-in-register,
- * and the output is the old value.
- *
- * Apparently this is complicated for archs that don't support
- * the memw_locked like we do (or it's broken or whatever).
- *
- * Kind of the lynchpin of the rest of the generically defined routines.
- * Remember V2 had that bug with dotnew predicate set by memw_locked.
- *
- * "old" is "expected" old val, __oldval is actual old value
- */
-static inline int arch_atomic_cmpxchg(atomic_t *v, int old, int new)
-{
- int __oldval;
+#define arch_atomic_xchg(v, new) \
+ (arch_xchg(&((v)->counter), (new)))

- asm volatile(
- "1: %0 = memw_locked(%1);\n"
- " { P0 = cmp.eq(%0,%2);\n"
- " if (!P0.new) jump:nt 2f; }\n"
- " memw_locked(%1,P0) = %3;\n"
- " if (!P0) jump 1b;\n"
- "2:\n"
- : "=&r" (__oldval)
- : "r" (&v->counter), "r" (old), "r" (new)
- : "memory", "p0"
- );
-
- return __oldval;
-}
+#define arch_atomic_cmpxchg(v, old, new) \
+ (arch_cmpxchg(&((v)->counter), (old), (new)))

#define ATOMIC_OP(op) \
static inline void arch_atomic_##op(int i, atomic_t *v) \
--
2.30.2