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Subject[PATCH] locking/atomics: Combine the atomic_andnot() and atomic64_andnot() API definitions

* Ingo Molnar <mingo@kernel.org> wrote:

> Note that the simplest definition block is now:
>
> #ifndef atomic_cmpxchg_relaxed
> # define atomic_cmpxchg_relaxed atomic_cmpxchg
> # define atomic_cmpxchg_acquire atomic_cmpxchg
> # define atomic_cmpxchg_release atomic_cmpxchg
> #else
> # ifndef atomic_cmpxchg
> # define atomic_cmpxchg(...) __atomic_op_fence(atomic_cmpxchg, __VA_ARGS__)
> # define atomic_cmpxchg_acquire(...) __atomic_op_acquire(atomic_cmpxchg, __VA_ARGS__)
> # define atomic_cmpxchg_release(...) __atomic_op_release(atomic_cmpxchg, __VA_ARGS__)
> # endif
> #endif
>
> ... which is very readable!
>
> The total linecount reduction of the two patches is pretty significant as well:
>
> include/linux/atomic.h | 1063 ++++++++++++++++--------------------------------
> 1 file changed, 343 insertions(+), 720 deletions(-)

BTW., I noticed two asymmetries while cleaning up this code:

==============>

#ifdef atomic_andnot

#ifndef atomic_fetch_andnot_relaxed
# define atomic_fetch_andnot_relaxed atomic_fetch_andnot
# define atomic_fetch_andnot_acquire atomic_fetch_andnot
# define atomic_fetch_andnot_release atomic_fetch_andnot
#else
# ifndef atomic_fetch_andnot
# define atomic_fetch_andnot(...) __atomic_op_fence(atomic_fetch_andnot, __VA_ARGS__)
# define atomic_fetch_andnot_acquire(...) __atomic_op_acquire(atomic_fetch_andnot, __VA_ARGS__)
# define atomic_fetch_andnot_release(...) __atomic_op_release(atomic_fetch_andnot, __VA_ARGS__)
# endif
#endif

#endif /* atomic_andnot */

...

#ifdef atomic64_andnot

#ifndef atomic64_fetch_andnot_relaxed
# define atomic64_fetch_andnot_relaxed atomic64_fetch_andnot
# define atomic64_fetch_andnot_acquire atomic64_fetch_andnot
# define atomic64_fetch_andnot_release atomic64_fetch_andnot
#else
# ifndef atomic64_fetch_andnot
# define atomic64_fetch_andnot(...) __atomic_op_fence(atomic64_fetch_andnot, __VA_ARGS__)
# define atomic64_fetch_andnot_acquire(...) __atomic_op_acquire(atomic64_fetch_andnot, __VA_ARGS__)
# define atomic64_fetch_andnot_release(...) __atomic_op_release(atomic64_fetch_andnot, __VA_ARGS__)
# endif
#endif

#endif /* atomic64_andnot */

<==============

Why do these two API groups have an outer condition, i.e.:

#ifdef atomic_andnot
...
#endif /* atomic_andnot */
...
#ifdef atomic64_andnot
...
#endif /* atomic64_andnot */

because the base APIs themselves are optional and have a default implementation:

#ifndef atomic_andnot
...
#endif
...
#ifndef atomic64_andnot
...
#endif

I think it's overall cleaner if we combine them into continous blocks, defining
all variants of an API group in a single place:

#ifdef atomic_andnot
#else
#endif

etc.

The patch below implements this.

Thanks,

Ingo

===================>
From f5efafa83af8c46b9e81b010b46caeeadb450179 Mon Sep 17 00:00:00 2001
From: Ingo Molnar <mingo@kernel.org>
Date: Sat, 5 May 2018 10:46:41 +0200
Subject: [PATCH] locking/atomics: Combine the atomic_andnot() and atomic64_andnot() API definitions

The atomic_andnot() and atomic64_andnot() are defined in 4 separate groups
spred out in the atomic.h header:

#ifdef atomic_andnot
...
#endif /* atomic_andnot */
...
#ifndef atomic_andnot
...
#endif
...
#ifdef atomic64_andnot
...
#endif /* atomic64_andnot */
...
#ifndef atomic64_andnot
...
#endif

Combine them into unify them into two groups:

#ifdef atomic_andnot
#else
#endif

...

#ifdef atomic64_andnot
#else
#endif

So that one API group is defined in a single place within the header.

Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
include/linux/atomic.h | 72 +++++++++++++++++++++++++-------------------------
1 file changed, 36 insertions(+), 36 deletions(-)

diff --git a/include/linux/atomic.h b/include/linux/atomic.h
index 352ecc72d7f5..1176cf7c6f03 100644
--- a/include/linux/atomic.h
+++ b/include/linux/atomic.h
@@ -205,22 +205,6 @@
# endif
#endif

-#ifdef atomic_andnot
-
-#ifndef atomic_fetch_andnot_relaxed
-# define atomic_fetch_andnot_relaxed atomic_fetch_andnot
-# define atomic_fetch_andnot_acquire atomic_fetch_andnot
-# define atomic_fetch_andnot_release atomic_fetch_andnot
-#else
-# ifndef atomic_fetch_andnot
-# define atomic_fetch_andnot(...) __atomic_op_fence(atomic_fetch_andnot, __VA_ARGS__)
-# define atomic_fetch_andnot_acquire(...) __atomic_op_acquire(atomic_fetch_andnot, __VA_ARGS__)
-# define atomic_fetch_andnot_release(...) __atomic_op_release(atomic_fetch_andnot, __VA_ARGS__)
-# endif
-#endif
-
-#endif /* atomic_andnot */
-
#ifndef atomic_fetch_xor_relaxed
# define atomic_fetch_xor_relaxed atomic_fetch_xor
# define atomic_fetch_xor_acquire atomic_fetch_xor
@@ -338,7 +322,22 @@ static inline int atomic_add_unless(atomic_t *v, int a, int u)
# define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
#endif

-#ifndef atomic_andnot
+#ifdef atomic_andnot
+
+#ifndef atomic_fetch_andnot_relaxed
+# define atomic_fetch_andnot_relaxed atomic_fetch_andnot
+# define atomic_fetch_andnot_acquire atomic_fetch_andnot
+# define atomic_fetch_andnot_release atomic_fetch_andnot
+#else
+# ifndef atomic_fetch_andnot
+# define atomic_fetch_andnot(...) __atomic_op_fence(atomic_fetch_andnot, __VA_ARGS__)
+# define atomic_fetch_andnot_acquire(...) __atomic_op_acquire(atomic_fetch_andnot, __VA_ARGS__)
+# define atomic_fetch_andnot_release(...) __atomic_op_release(atomic_fetch_andnot, __VA_ARGS__)
+# endif
+#endif
+
+#else /* !atomic_andnot: */
+
static inline void atomic_andnot(int i, atomic_t *v)
{
atomic_and(~i, v);
@@ -363,7 +362,8 @@ static inline int atomic_fetch_andnot_release(int i, atomic_t *v)
{
return atomic_fetch_and_release(~i, v);
}
-#endif
+
+#endif /* !atomic_andnot */

/**
* atomic_inc_not_zero_hint - increment if not null
@@ -600,22 +600,6 @@ static inline int atomic_dec_if_positive(atomic_t *v)
# endif
#endif

-#ifdef atomic64_andnot
-
-#ifndef atomic64_fetch_andnot_relaxed
-# define atomic64_fetch_andnot_relaxed atomic64_fetch_andnot
-# define atomic64_fetch_andnot_acquire atomic64_fetch_andnot
-# define atomic64_fetch_andnot_release atomic64_fetch_andnot
-#else
-# ifndef atomic64_fetch_andnot
-# define atomic64_fetch_andnot(...) __atomic_op_fence(atomic64_fetch_andnot, __VA_ARGS__)
-# define atomic64_fetch_andnot_acquire(...) __atomic_op_acquire(atomic64_fetch_andnot, __VA_ARGS__)
-# define atomic64_fetch_andnot_release(...) __atomic_op_release(atomic64_fetch_andnot, __VA_ARGS__)
-# endif
-#endif
-
-#endif /* atomic64_andnot */
-
#ifndef atomic64_fetch_xor_relaxed
# define atomic64_fetch_xor_relaxed atomic64_fetch_xor
# define atomic64_fetch_xor_acquire atomic64_fetch_xor
@@ -672,7 +656,22 @@ static inline int atomic_dec_if_positive(atomic_t *v)
# define atomic64_try_cmpxchg_release atomic64_try_cmpxchg
#endif

-#ifndef atomic64_andnot
+#ifdef atomic64_andnot
+
+#ifndef atomic64_fetch_andnot_relaxed
+# define atomic64_fetch_andnot_relaxed atomic64_fetch_andnot
+# define atomic64_fetch_andnot_acquire atomic64_fetch_andnot
+# define atomic64_fetch_andnot_release atomic64_fetch_andnot
+#else
+# ifndef atomic64_fetch_andnot
+# define atomic64_fetch_andnot(...) __atomic_op_fence(atomic64_fetch_andnot, __VA_ARGS__)
+# define atomic64_fetch_andnot_acquire(...) __atomic_op_acquire(atomic64_fetch_andnot, __VA_ARGS__)
+# define atomic64_fetch_andnot_release(...) __atomic_op_release(atomic64_fetch_andnot, __VA_ARGS__)
+# endif
+#endif
+
+#else /* !atomic64_andnot: */
+
static inline void atomic64_andnot(long long i, atomic64_t *v)
{
atomic64_and(~i, v);
@@ -697,7 +696,8 @@ static inline long long atomic64_fetch_andnot_release(long long i, atomic64_t *v
{
return atomic64_fetch_and_release(~i, v);
}
-#endif
+
+#endif /* !atomic64_andnot */

#define atomic64_cond_read_relaxed(v, c) smp_cond_load_relaxed(&(v)->counter, (c))
#define atomic64_cond_read_acquire(v, c) smp_cond_load_acquire(&(v)->counter, (c))
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