locking/atomics: Switch to generated fallbacks

As a step to ensuring the atomic* APIs are consistent, switch to fallbacks
generated by gen-atomic-fallback.sh.

These are checked in rather than generated with Kbuild, since:

* This allows inspection of the atomics with git grep and ctags on a
  pristine tree, which Linus strongly prefers being able to do.

* The fallbacks are not affected by machine details or configuration
  options, so it is not necessary to regenerate them to take these into
  account.

* These are included by files required *very* early in the build process
  (e.g. for generating bounds.h), and we'd rather not complicate the
  top-level Kbuild file with dependencies.

The new fallback header should be equivalent to the old fallbacks in
<linux/atomic.h>, but:

* It is formatted a little differently due to scripting ensuring things
  are more regular than they used to be.

* Fallbacks are now expanded in-place as static inline functions rather
  than macros.

* The prototypes for fallbacks are arragned consistently with the return
  type on a separate line to try to keep to a sensible line length.

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>
Acked-by: Will Deacon <will.deacon@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: catalin.marinas@arm.com
Cc: linuxdrivers@attotech.com
Cc: dvyukov@google.com
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: arnd@arndb.de
Cc: aryabinin@virtuozzo.com
Cc: glider@google.com
Link: http://lkml.kernel.org/r/20180904104830.2975-3-mark.rutland@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

2 files changed, 2295 insertions, 1240 deletions

diff --git a/include/linux/atomic-fallback.h b/include/linux/atomic-fallback.h
new file mode 100644
index 000000000000..1c02c0112fbb
--- /dev/null
+++ b/include/linux/atomic-fallback.h
@@ -0,0 +1,2294 @@
+// SPDX-License-Identifier: GPL-2.0
+
+// Generated by scripts/atomic/gen-atomic-fallback.sh
+// DO NOT MODIFY THIS FILE DIRECTLY
+
+#ifndef _LINUX_ATOMIC_FALLBACK_H
+#define _LINUX_ATOMIC_FALLBACK_H
+
+#ifndef xchg_relaxed
+#define xchg_relaxed            xchg
+#define xchg_acquire            xchg
+#define xchg_release            xchg
+#else /* xchg_relaxed */
+
+#ifndef xchg_acquire
+#define xchg_acquire(...) \
+        __atomic_op_acquire(xchg, __VA_ARGS__)
+#endif
+
+#ifndef xchg_release
+#define xchg_release(...) \
+        __atomic_op_release(xchg, __VA_ARGS__)
+#endif
+
+#ifndef xchg
+#define xchg(...) \
+        __atomic_op_fence(xchg, __VA_ARGS__)
+#endif
+
+#endif /* xchg_relaxed */
+
+#ifndef cmpxchg_relaxed
+#define cmpxchg_relaxed         cmpxchg
+#define cmpxchg_acquire         cmpxchg
+#define cmpxchg_release         cmpxchg
+#else /* cmpxchg_relaxed */
+
+#ifndef cmpxchg_acquire
+#define cmpxchg_acquire(...) \
+        __atomic_op_acquire(cmpxchg, __VA_ARGS__)
+#endif
+
+#ifndef cmpxchg_release
+#define cmpxchg_release(...) \
+        __atomic_op_release(cmpxchg, __VA_ARGS__)
+#endif
+
+#ifndef cmpxchg
+#define cmpxchg(...) \
+        __atomic_op_fence(cmpxchg, __VA_ARGS__)
+#endif
+
+#endif /* cmpxchg_relaxed */
+
+#ifndef cmpxchg64_relaxed
+#define cmpxchg64_relaxed               cmpxchg64
+#define cmpxchg64_acquire               cmpxchg64
+#define cmpxchg64_release               cmpxchg64
+#else /* cmpxchg64_relaxed */
+
+#ifndef cmpxchg64_acquire
+#define cmpxchg64_acquire(...) \
+        __atomic_op_acquire(cmpxchg64, __VA_ARGS__)
+#endif
+
+#ifndef cmpxchg64_release
+#define cmpxchg64_release(...) \
+        __atomic_op_release(cmpxchg64, __VA_ARGS__)
+#endif
+
+#ifndef cmpxchg64
+#define cmpxchg64(...) \
+        __atomic_op_fence(cmpxchg64, __VA_ARGS__)
+#endif
+
+#endif /* cmpxchg64_relaxed */
+
+#ifndef atomic_read_acquire
+static inline int
+atomic_read_acquire(const atomic_t *v)
+{
+        return smp_load_acquire(&(v)->counter);
+}
+#define atomic_read_acquire atomic_read_acquire
+#endif
+
+#ifndef atomic_set_release
+static inline void
+atomic_set_release(atomic_t *v, int i)
+{
+        smp_store_release(&(v)->counter, i);
+}
+#define atomic_set_release atomic_set_release
+#endif
+
+#ifndef atomic_add_return_relaxed
+#define atomic_add_return_acquire atomic_add_return
+#define atomic_add_return_release atomic_add_return
+#define atomic_add_return_relaxed atomic_add_return
+#else /* atomic_add_return_relaxed */
+
+#ifndef atomic_add_return_acquire
+static inline int
+atomic_add_return_acquire(int i, atomic_t *v)
+{
+        int ret = atomic_add_return_relaxed(i, v);
+        __atomic_acquire_fence();
+        return ret;
+}
+#define atomic_add_return_acquire atomic_add_return_acquire
+#endif
+
+#ifndef atomic_add_return_release
+static inline int
+atomic_add_return_release(int i, atomic_t *v)
+{
+        __atomic_release_fence();
+        return atomic_add_return_relaxed(i, v);
+}
+#define atomic_add_return_release atomic_add_return_release
+#endif
+
+#ifndef atomic_add_return
+static inline int
+atomic_add_return(int i, atomic_t *v)
+{
+        int ret;
+        __atomic_pre_full_fence();
+        ret = atomic_add_return_relaxed(i, v);
+        __atomic_post_full_fence();
+        return ret;
+}
+#define atomic_add_return atomic_add_return
+#endif
+
+#endif /* atomic_add_return_relaxed */
+
+#ifndef atomic_fetch_add_relaxed
+#define atomic_fetch_add_acquire atomic_fetch_add
+#define atomic_fetch_add_release atomic_fetch_add
+#define atomic_fetch_add_relaxed atomic_fetch_add
+#else /* atomic_fetch_add_relaxed */
+
+#ifndef atomic_fetch_add_acquire
+static inline int
+atomic_fetch_add_acquire(int i, atomic_t *v)
+{
+        int ret = atomic_fetch_add_relaxed(i, v);
+        __atomic_acquire_fence();
+        return ret;
+}
+#define atomic_fetch_add_acquire atomic_fetch_add_acquire
+#endif
+
+#ifndef atomic_fetch_add_release
+static inline int
+atomic_fetch_add_release(int i, atomic_t *v)
+{
+        __atomic_release_fence();
+        return atomic_fetch_add_relaxed(i, v);
+}
+#define atomic_fetch_add_release atomic_fetch_add_release
+#endif
+
+#ifndef atomic_fetch_add
+static inline int
+atomic_fetch_add(int i, atomic_t *v)
+{
+        int ret;
+        __atomic_pre_full_fence();
+        ret = atomic_fetch_add_relaxed(i, v);
+        __atomic_post_full_fence();
+        return ret;
+}
+#define atomic_fetch_add atomic_fetch_add
+#endif
+
+#endif /* atomic_fetch_add_relaxed */
+
+#ifndef atomic_sub_return_relaxed
+#define atomic_sub_return_acquire atomic_sub_return
+#define atomic_sub_return_release atomic_sub_return
+#define atomic_sub_return_relaxed atomic_sub_return
+#else /* atomic_sub_return_relaxed */
+
+#ifndef atomic_sub_return_acquire
+static inline int
+atomic_sub_return_acquire(int i, atomic_t *v)
+{
+        int ret = atomic_sub_return_relaxed(i, v);
+        __atomic_acquire_fence();
+        return ret;
+}
+#define atomic_sub_return_acquire atomic_sub_return_acquire
+#endif
+
+#ifndef atomic_sub_return_release
+static inline int
+atomic_sub_return_release(int i, atomic_t *v)
+{
+        __atomic_release_fence();
+        return atomic_sub_return_relaxed(i, v);
+}
+#define atomic_sub_return_release atomic_sub_return_release
+#endif
+
+#ifndef atomic_sub_return