locking/atomic: scripts: simplify raw_atomic*() definitions

Currently each ordering variant has several potential definitions,
with a mixture of preprocessor and C definitions, including several
copies of its C prototype, e.g.

| #if defined(arch_atomic_fetch_andnot_acquire)
| #define raw_atomic_fetch_andnot_acquire arch_atomic_fetch_andnot_acquire
| #elif defined(arch_atomic_fetch_andnot_relaxed)
| static __always_inline int
| raw_atomic_fetch_andnot_acquire(int i, atomic_t *v)
| {
|       int ret = arch_atomic_fetch_andnot_relaxed(i, v);
|       __atomic_acquire_fence();
|       return ret;
| }
| #elif defined(arch_atomic_fetch_andnot)
| #define raw_atomic_fetch_andnot_acquire arch_atomic_fetch_andnot
| #else
| static __always_inline int
| raw_atomic_fetch_andnot_acquire(int i, atomic_t *v)
| {
|       return raw_atomic_fetch_and_acquire(~i, v);
| }
| #endif

Make this a bit simpler by defining the C prototype once, and writing
the various potential definitions as plain C code guarded by ifdeffery.
For example, the above becomes:

| static __always_inline int
| raw_atomic_fetch_andnot_acquire(int i, atomic_t *v)
| {
| #if defined(arch_atomic_fetch_andnot_acquire)
|         return arch_atomic_fetch_andnot_acquire(i, v);
| #elif defined(arch_atomic_fetch_andnot_relaxed)
|         int ret = arch_atomic_fetch_andnot_relaxed(i, v);
|         __atomic_acquire_fence();
|         return ret;
| #elif defined(arch_atomic_fetch_andnot)
|         return arch_atomic_fetch_andnot(i, v);
| #else
|         return raw_atomic_fetch_and_acquire(~i, v);
| #endif
| }

Which is far easier to read. As we now always have a single copy of the
C prototype wrapping all the potential definitions, we now have an
obvious single location for kerneldoc comments.

At the same time, the fallbacks for raw_atomic*_xhcg() are made to use
'new' rather than 'i' as the name of the new value. This is what the
existing fallback template used, and is more consistent with the
raw_atomic{_try,}cmpxchg() fallbacks.

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

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230605070124.3741859-24-mark.rutland@arm.com

1 files changed, 13 insertions, 13 deletions

diff --git a/include/linux/atomic/atomic-long.h b/include/linux/atomic/atomic-long.h
index 63e0b4078ebd..f564f71ff8af 100644
--- a/include/linux/atomic/atomic-long.h
+++ b/include/linux/atomic/atomic-long.h
@@ -622,42 +622,42 @@ raw_atomic_long_fetch_xor_relaxed(long i, atomic_long_t *v)
 }
 
 static __always_inline long
-raw_atomic_long_xchg(atomic_long_t *v, long i)
+raw_atomic_long_xchg(atomic_long_t *v, long new)
 {
 #ifdef CONFIG_64BIT
-	return raw_atomic64_xchg(v, i);
+	return raw_atomic64_xchg(v, new);
 #else
-	return raw_atomic_xchg(v, i);
+	return raw_atomic_xchg(v, new);
 #endif
 }
 
 static __always_inline long
-raw_atomic_long_xchg_acquire(atomic_long_t *v, long i)
+raw_atomic_long_xchg_acquire(atomic_long_t *v, long new)
 {
 #ifdef CONFIG_64BIT
-	return raw_atomic64_xchg_acquire(v, i);
+	return raw_atomic64_xchg_acquire(v, new);
 #else
-	return raw_atomic_xchg_acquire(v, i);
+	return raw_atomic_xchg_acquire(v, new);
 #endif
 }
 
 static __always_inline long
-raw_atomic_long_xchg_release(atomic_long_t *v, long i)
+raw_atomic_long_xchg_release(atomic_long_t *v, long new)
 {
 #ifdef CONFIG_64BIT
-	return raw_atomic64_xchg_release(v, i);
+	return raw_atomic64_xchg_release(v, new);
 #else
-	return raw_atomic_xchg_release(v, i);
+	return raw_atomic_xchg_release(v, new);
 #endif
 }
 
 static __always_inline long
-raw_atomic_long_xchg_relaxed(atomic_long_t *v, long i)
+raw_atomic_long_xchg_relaxed(atomic_long_t *v, long new)
 {
 #ifdef CONFIG_64BIT
-	return raw_atomic64_xchg_relaxed(v, i);
+	return raw_atomic64_xchg_relaxed(v, new);
 #else
-	return raw_atomic_xchg_relaxed(v, i);
+	return raw_atomic_xchg_relaxed(v, new);
 #endif
 }
 
@@ -872,4 +872,4 @@ raw_atomic_long_dec_if_positive(atomic_long_t *v)
 }
 
 #endif /* _LINUX_ATOMIC_LONG_H */
-// ad09f849db0db5b30c82e497eeb9056a394c5f22
+// e785d25cc3f220b7d473d36aac9da85dd7eb13a8