linux-kernel - [PATCH 08/33] locking/atomic: atomic: simplify ifdeffery

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Date:   Mon, 10 May 2021 10:37:28 +0100
From:   Mark Rutland <mark.rutland@....com>
To:     linux-kernel@...r.kernel.org, will@...nel.org,
        boqun.feng@...il.com, peterz@...radead.org
Cc:     aou@...s.berkeley.edu, arnd@...db.de, bcain@...eaurora.org,
        benh@...nel.crashing.org, chris@...kel.net, dalias@...c.org,
        davem@...emloft.net, deanbo422@...il.com, deller@....de,
        geert@...ux-m68k.org, green.hu@...il.com, guoren@...nel.org,
        ink@...assic.park.msu.ru, James.Bottomley@...senPartnership.com,
        jcmvbkbc@...il.com, jonas@...thpole.se, ley.foon.tan@...el.com,
        linux@...linux.org.uk, mark.rutland@....com, mattst88@...il.com,
        monstr@...str.eu, mpe@...erman.id.au, nickhu@...estech.com,
        palmer@...belt.com, paulus@...ba.org, paul.walmsley@...ive.com,
        rth@...ddle.net, shorne@...il.com,
        stefan.kristiansson@...nalahti.fi, tsbogend@...ha.franken.de,
        vgupta@...opsys.com, ysato@...rs.sourceforge.jp
Subject: [PATCH 08/33] locking/atomic: atomic: simplify ifdeffery

Now that asm-generic/atomic.h is only used by architectures without any
architecture-specific atomic definitions, we know that there will be no
architecture-specific implementations to override, and can remove the
ifdeffery this has previously required, bringing it into line with
asm-generic/atomic64.h.

At the same time, we can implement atomic_add() and atomic_sub()
directly using ATOMIC_OP(), since we know architectures won't provide
atomic_add_return() or atomic_sub_return().

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

Signed-off-by: Mark Rutland <mark.rutland@....com>
Cc: Arnd Bergmann <arnd@...db.de>
Cc: Boqun Feng <boqun.feng@...il.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Will Deacon <will@...nel.org>
---
 include/asm-generic/atomic.h | 46 ++++----------------------------------------
 1 file changed, 4 insertions(+), 42 deletions(-)

diff --git a/include/asm-generic/atomic.h b/include/asm-generic/atomic.h
index d4bf803d6491..316c82a27b0a 100644
--- a/include/asm-generic/atomic.h
+++ b/include/asm-generic/atomic.h
@@ -93,65 +93,27 @@ static inline int atomic_fetch_##op(int i, atomic_t *v)			\
 
 #endif /* CONFIG_SMP */
 
-#ifndef atomic_add_return
 ATOMIC_OP_RETURN(add, +)
-#endif
-
-#ifndef atomic_sub_return
 ATOMIC_OP_RETURN(sub, -)
-#endif
 
-#ifndef atomic_fetch_add
 ATOMIC_FETCH_OP(add, +)
-#endif
-
-#ifndef atomic_fetch_sub
 ATOMIC_FETCH_OP(sub, -)
-#endif
-
-#ifndef atomic_fetch_and
 ATOMIC_FETCH_OP(and, &)
-#endif
-
-#ifndef atomic_fetch_or
 ATOMIC_FETCH_OP(or, |)
-#endif
-
-#ifndef atomic_fetch_xor
 ATOMIC_FETCH_OP(xor, ^)
-#endif
 
-#ifndef atomic_and
+ATOMIC_OP(add, +)
+ATOMIC_OP(sub, -)
 ATOMIC_OP(and, &)
-#endif
-
-#ifndef atomic_or
 ATOMIC_OP(or, |)
-#endif
-
-#ifndef atomic_xor
 ATOMIC_OP(xor, ^)
-#endif
 
 #undef ATOMIC_FETCH_OP
 #undef ATOMIC_OP_RETURN
 #undef ATOMIC_OP
 
-#ifndef atomic_read
-#define atomic_read(v)	READ_ONCE((v)->counter)
-#endif
-
-#define atomic_set(v, i) WRITE_ONCE(((v)->counter), (i))
-
-static inline void atomic_add(int i, atomic_t *v)
-{
-	atomic_add_return(i, v);
-}
-
-static inline void atomic_sub(int i, atomic_t *v)
-{
-	atomic_sub_return(i, v);
-}
+#define atomic_read(v)			READ_ONCE((v)->counter)
+#define atomic_set(v, i)		WRITE_ONCE(((v)->counter), (i))
 
 #define atomic_xchg(ptr, v)		(xchg(&(ptr)->counter, (v)))
 #define atomic_cmpxchg(v, old, new)	(cmpxchg(&((v)->counter), (old), (new)))
-- 
2.11.0