[RFC][PATCH 5/7] asm-generic/atomic: Add try_cmpxchg() fallbacks

Peter Zijlstra
2020-08-27T16:22:10Z

Only x86 provides try_cmpxchg() outside of the atomic_t interfaces,
provide generic fallbacks to create this interface from the widely
available cmpxchg() function.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Will Deacon <will@kernel.org>
---
arch/x86/include/asm/atomic.h | 2
arch/x86/include/asm/atomic64_64.h | 2
arch/x86/include/asm/cmpxchg.h | 2
include/asm-generic/atomic-instrumented.h | 216 ++++++++++++++++++------------
include/linux/atomic-arch-fallback.h | 90 +++++++++++-
include/linux/atomic-fallback.h | 90 +++++++++++-
scripts/atomic/gen-atomic-fallback.sh | 63 +++++++-
scripts/atomic/gen-atomic-instrumented.sh | 29 +++-
8 files changed, 372 insertions(+), 122 deletions(-)

--- a/arch/x86/include/asm/atomic.h
+++ b/arch/x86/include/asm/atomic.h
@@ -199,7 +199,7 @@ static __always_inline int arch_atomic_c

static __always_inline bool arch_atomic_try_cmpxchg(atomic_t *v, int *old, int new)
{
- return try_cmpxchg(&v->counter, old, new);
+ return arch_try_cmpxchg(&v->counter, old, new);
}
#define arch_atomic_try_cmpxchg arch_atomic_try_cmpxchg

--- a/arch/x86/include/asm/atomic64_64.h
+++ b/arch/x86/include/asm/atomic64_64.h
@@ -187,7 +187,7 @@ static inline s64 arch_atomic64_cmpxchg(

static __always_inline bool arch_atomic64_try_cmpxchg(atomic64_t *v, s64 *old, s64 new)
{
- return try_cmpxchg(&v->counter, old, new);
+ return arch_try_cmpxchg(&v->counter, old, new);
}
#define arch_atomic64_try_cmpxchg arch_atomic64_try_cmpxchg

--- a/arch/x86/include/asm/cmpxchg.h
+++ b/arch/x86/include/asm/cmpxchg.h
@@ -221,7 +221,7 @@ extern void __add_wrong_size(void)
#define __try_cmpxchg(ptr, pold, new, size) \
__raw_try_cmpxchg((ptr), (pold), (new), (size), LOCK_PREFIX)

-#define try_cmpxchg(ptr, pold, new) \
+#define arch_try_cmpxchg(ptr, pold, new) \
__try_cmpxchg((ptr), (pold), (new), sizeof(*(ptr)))

/*
--- a/include/asm-generic/atomic-instrumented.h
+++ b/include/asm-generic/atomic-instrumented.h
@@ -1642,148 +1642,192 @@ atomic64_dec_if_positive(atomic64_t *v)
#endif

#if !defined(arch_xchg_relaxed) || defined(arch_xchg)
-#define xchg(ptr, ...) \
-({ \
- typeof(ptr) __ai_ptr = (ptr); \
- instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
- arch_xchg(__ai_ptr, __VA_ARGS__); \
+#define xchg(ptr, ...) \
+({ \
+ typeof(ptr) __ai_ptr = (ptr); \
+ instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
+ arch_xchg(__ai_ptr, __VA_ARGS__); \
})
#endif

#if defined(arch_xchg_acquire)
-#define xchg_acquire(ptr, ...) \
-({ \
- typeof(ptr) __ai_ptr = (ptr); \
- instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
- arch_xchg_acquire(__ai_ptr, __VA_ARGS__); \
+#define xchg_acquire(ptr, ...) \
+({ \
+ typeof(ptr) __ai_ptr = (ptr); \
+ instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
+ arch_xchg_acquire(__ai_ptr, __VA_ARGS__); \
})
#endif

#if defined(arch_xchg_release)
-#define xchg_release(ptr, ...) \
-({ \
- typeof(ptr) __ai_ptr = (ptr); \
- instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
- arch_xchg_release(__ai_ptr, __VA_ARGS__); \
+#define xchg_release(ptr, ...) \
+({ \
+ typeof(ptr) __ai_ptr = (ptr); \
+ instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
+ arch_xchg_release(__ai_ptr, __VA_ARGS__); \
})
#endif

#if defined(arch_xchg_relaxed)
-#define xchg_relaxed(ptr, ...) \
-({ \
- typeof(ptr) __ai_ptr = (ptr); \
- instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
- arch_xchg_relaxed(__ai_ptr, __VA_ARGS__); \
+#define xchg_relaxed(ptr, ...) \
+({ \
+ typeof(ptr) __ai_ptr = (ptr); \
+ instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
+ arch_xchg_relaxed(__ai_ptr, __VA_ARGS__); \
})
#endif

#if !defined(arch_cmpxchg_relaxed) || defined(arch_cmpxchg)
-#define cmpxchg(ptr, ...) \
-({ \
- typeof(ptr) __ai_ptr = (ptr); \
- instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
- arch_cmpxchg(__ai_ptr, __VA_ARGS__); \
+#define cmpxchg(ptr, ...) \
+({ \
+ typeof(ptr) __ai_ptr = (ptr); \
+ instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
+ arch_cmpxchg(__ai_ptr, __VA_ARGS__); \
})
#endif

#if defined(arch_cmpxchg_acquire)
-#define cmpxchg_acquire(ptr, ...) \
-({ \
- typeof(ptr) __ai_ptr = (ptr); \
- instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
- arch_cmpxchg_acquire(__ai_ptr, __VA_ARGS__); \
+#define cmpxchg_acquire(ptr, ...) \
+({ \
+ typeof(ptr) __ai_ptr = (ptr); \
+ instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
+ arch_cmpxchg_acquire(__ai_ptr, __VA_ARGS__); \
})
#endif

#if defined(arch_cmpxchg_release)
-#define cmpxchg_release(ptr, ...) \
-({ \
- typeof(ptr) __ai_ptr = (ptr); \
- instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
- arch_cmpxchg_release(__ai_ptr, __VA_ARGS__); \
+#define cmpxchg_release(ptr, ...) \
+({ \
+ typeof(ptr) __ai_ptr = (ptr); \
+ instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
+ arch_cmpxchg_release(__ai_ptr, __VA_ARGS__); \
})
#endif

#if defined(arch_cmpxchg_relaxed)
-#define cmpxchg_relaxed(ptr, ...) \
-({ \
- typeof(ptr) __ai_ptr = (ptr); \
- instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
- arch_cmpxchg_relaxed(__ai_ptr, __VA_ARGS__); \
+#define cmpxchg_relaxed(ptr, ...) \
+({ \
+ typeof(ptr) __ai_ptr = (ptr); \
+ instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
+ arch_cmpxchg_relaxed(__ai_ptr, __VA_ARGS__); \
})
#endif

#if !defined(arch_cmpxchg64_relaxed) || defined(arch_cmpxchg64)
-#define cmpxchg64(ptr, ...) \
-({ \
- typeof(ptr) __ai_ptr = (ptr); \
- instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
- arch_cmpxchg64(__ai_ptr, __VA_ARGS__); \
+#define cmpxchg64(ptr, ...) \
+({ \
+ typeof(ptr) __ai_ptr = (ptr); \
+ instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
+ arch_cmpxchg64(__ai_ptr, __VA_ARGS__); \
})
#endif

#if defined(arch_cmpxchg64_acquire)
-#define cmpxchg64_acquire(ptr, ...) \
-({ \
- typeof(ptr) __ai_ptr = (ptr); \
- instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
- arch_cmpxchg64_acquire(__ai_ptr, __VA_ARGS__); \
+#define cmpxchg64_acquire(ptr, ...) \
+({ \
+ typeof(ptr) __ai_ptr = (ptr); \
+ instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
+ arch_cmpxchg64_acquire(__ai_ptr, __VA_ARGS__); \
})
#endif

#if defined(arch_cmpxchg64_release)
-#define cmpxchg64_release(ptr, ...) \
-({ \
- typeof(ptr) __ai_ptr = (ptr); \
- instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
- arch_cmpxchg64_release(__ai_ptr, __VA_ARGS__); \
+#define cmpxchg64_release(ptr, ...) \
+({ \
+ typeof(ptr) __ai_ptr = (ptr); \
+ instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
+ arch_cmpxchg64_release(__ai_ptr, __VA_ARGS__); \
})
#endif

#if defined(arch_cmpxchg64_relaxed)
-#define cmpxchg64_relaxed(ptr, ...) \
-({ \
- typeof(ptr) __ai_ptr = (ptr); \
- instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
- arch_cmpxchg64_relaxed(__ai_ptr, __VA_ARGS__); \
+#define cmpxchg64_relaxed(ptr, ...) \
+({ \
+ typeof(ptr) __ai_ptr = (ptr); \
+ instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
+ arch_cmpxchg64_relaxed(__ai_ptr, __VA_ARGS__); \
})
#endif

-#define cmpxchg_local(ptr, ...) \
-({ \
- typeof(ptr) __ai_ptr = (ptr); \
- instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
- arch_cmpxchg_local(__ai_ptr, __VA_ARGS__); \
+#if !defined(arch_try_cmpxchg_relaxed) || defined(arch_try_cmpxchg)
+#define try_cmpxchg(ptr, oldp, ...) \
+({ \
+ typeof(ptr) __ai_ptr = (ptr); \
+ typeof(oldp) __ai_oldp = (oldp); \
+ instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
+ instrument_atomic_write(__ai_oldp, sizeof(*__ai_oldp)); \
+ arch_try_cmpxchg(__ai_ptr, __ai_oldp, __VA_ARGS__); \
+})
+#endif
+
+#if defined(arch_try_cmpxchg_acquire)
+#define try_cmpxchg_acquire(ptr, oldp, ...) \
+({ \
+ typeof(ptr) __ai_ptr = (ptr); \
+ typeof(oldp) __ai_oldp = (oldp); \
+ instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
+ instrument_atomic_write(__ai_oldp, sizeof(*__ai_oldp)); \
+ arch_try_cmpxchg_acquire(__ai_ptr, __ai_oldp, __VA_ARGS__); \
+})
+#endif
+
+#if defined(arch_try_cmpxchg_release)
+#define try_cmpxchg_release(ptr, oldp, ...) \
+({ \
+ typeof(ptr) __ai_ptr = (ptr); \
+ typeof(oldp) __ai_oldp = (oldp); \
+ instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
+ instrument_atomic_write(__ai_oldp, sizeof(*__ai_oldp)); \
+ arch_try_cmpxchg_release(__ai_ptr, __ai_oldp, __VA_ARGS__); \
+})
+#endif
+
+#if defined(arch_try_cmpxchg_relaxed)
+#define try_cmpxchg_relaxed(ptr, oldp, ...) \
+({ \
+ typeof(ptr) __ai_ptr = (ptr); \
+ typeof(oldp) __ai_oldp = (oldp); \
+ instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
+ instrument_atomic_write(__ai_oldp, sizeof(*__ai_oldp)); \
+ arch_try_cmpxchg_relaxed(__ai_ptr, __ai_oldp, __VA_ARGS__); \
+})
+#endif
+
+#define cmpxchg_local(ptr, ...) \
+({ \
+ typeof(ptr) __ai_ptr = (ptr); \
+ instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
+ arch_cmpxchg_local(__ai_ptr, __VA_ARGS__); \
})

-#define cmpxchg64_local(ptr, ...) \
-({ \
- typeof(ptr) __ai_ptr = (ptr); \
- instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
- arch_cmpxchg64_local(__ai_ptr, __VA_ARGS__); \
+#define cmpxchg64_local(ptr, ...) \
+({ \
+ typeof(ptr) __ai_ptr = (ptr); \
+ instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
+ arch_cmpxchg64_local(__ai_ptr, __VA_ARGS__); \
})

-#define sync_cmpxchg(ptr, ...) \
-({ \
- typeof(ptr) __ai_ptr = (ptr); \
- instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
- arch_sync_cmpxchg(__ai_ptr, __VA_ARGS__); \
+#define sync_cmpxchg(ptr, ...) \
+({ \
+ typeof(ptr) __ai_ptr = (ptr); \
+ instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \
+ arch_sync_cmpxchg(__ai_ptr, __VA_ARGS__); \
})

-#define cmpxchg_double(ptr, ...) \
-({ \
- typeof(ptr) __ai_ptr = (ptr); \
- instrument_atomic_write(__ai_ptr, 2 * sizeof(*__ai_ptr)); \
- arch_cmpxchg_double(__ai_ptr, __VA_ARGS__); \
+#define cmpxchg_double(ptr, ...) \
+({ \
+ typeof(ptr) __ai_ptr = (ptr); \
+ instrument_atomic_write(__ai_ptr, 2 * sizeof(*__ai_ptr)); \
+ arch_cmpxchg_double(__ai_ptr, __VA_ARGS__); \
})

-#define cmpxchg_double_local(ptr, ...) \
-({ \
- typeof(ptr) __ai_ptr = (ptr); \
- instrument_atomic_write(__ai_ptr, 2 * sizeof(*__ai_ptr)); \
- arch_cmpxchg_double_local(__ai_ptr, __VA_ARGS__); \
+#define cmpxchg_double_local(ptr, ...) \
+({ \
+ typeof(ptr) __ai_ptr = (ptr); \
+ instrument_atomic_write(__ai_ptr, 2 * sizeof(*__ai_ptr)); \
+ arch_cmpxchg_double_local(__ai_ptr, __VA_ARGS__); \
})

#endif /* _ASM_GENERIC_ATOMIC_INSTRUMENTED_H */
-// 89bf97f3a7509b740845e51ddf31055b48a81f40
+// ff0fe7f81ee97f01f13bb78b0e3ce800bc56d9dd
--- a/include/linux/atomic-arch-fallback.h
+++ b/include/linux/atomic-arch-fallback.h
@@ -9,9 +9,9 @@
#include <linux/compiler.h>

#ifndef arch_xchg_relaxed
-#define arch_xchg_relaxed arch_xchg
-#define arch_xchg_acquire arch_xchg
-#define arch_xchg_release arch_xchg
+#define arch_xchg_acquire arch_xchg
+#define arch_xchg_release arch_xchg
+#define arch_xchg_relaxed arch_xchg
#else /* arch_xchg_relaxed */

#ifndef arch_xchg_acquire
@@ -32,9 +32,9 @@
#endif /* arch_xchg_relaxed */

#ifndef arch_cmpxchg_relaxed
-#define arch_cmpxchg_relaxed arch_cmpxchg
-#define arch_cmpxchg_acquire arch_cmpxchg
-#define arch_cmpxchg_release arch_cmpxchg
+#define arch_cmpxchg_acquire arch_cmpxchg
+#define arch_cmpxchg_release arch_cmpxchg
+#define arch_cmpxchg_relaxed arch_cmpxchg
#else /* arch_cmpxchg_relaxed */

#ifndef arch_cmpxchg_acquire
@@ -55,9 +55,9 @@
#endif /* arch_cmpxchg_relaxed */

#ifndef arch_cmpxchg64_relaxed
-#define arch_cmpxchg64_relaxed arch_cmpxchg64
-#define arch_cmpxchg64_acquire arch_cmpxchg64
-#define arch_cmpxchg64_release arch_cmpxchg64
+#define arch_cmpxchg64_acquire arch_cmpxchg64
+#define arch_cmpxchg64_release arch_cmpxchg64
+#define arch_cmpxchg64_relaxed arch_cmpxchg64
#else /* arch_cmpxchg64_relaxed */

#ifndef arch_cmpxchg64_acquire
@@ -77,6 +77,76 @@

#endif /* arch_cmpxchg64_relaxed */

+#ifndef arch_try_cmpxchg_relaxed
+#ifdef arch_try_cmpxchg
+#define arch_try_cmpxchg_acquire arch_try_cmpxchg
+#define arch_try_cmpxchg_release arch_try_cmpxchg
+#define arch_try_cmpxchg_relaxed arch_try_cmpxchg
+#endif /* arch_try_cmpxchg */
+
+#ifndef arch_try_cmpxchg
+#define arch_try_cmpxchg(_ptr, _oldp, _new) \
+({ \
+ typeof(*(_ptr)) *___op = (_oldp), ___o = *___op, ___r; \
+ ___r = arch_cmpxchg((_ptr), ___o, (_new)); \
+ if (unlikely(___r != ___o)) \
+ *___op = ___r; \
+ likely(___r == ___o); \
+})
+#endif /* arch_try_cmpxchg */
+
+#ifndef arch_try_cmpxchg_acquire
+#define arch_try_cmpxchg_acquire(_ptr, _oldp, _new) \
+({ \
+ typeof(*(_ptr)) *___op = (_oldp), ___o = *___op, ___r; \
+ ___r = arch_cmpxchg_acquire((_ptr), ___o, (_new)); \
+ if (unlikely(___r != ___o)) \
+ *___op = ___r; \
+ likely(___r == ___o); \
+})
+#endif /* arch_try_cmpxchg_acquire */
+
+#ifndef arch_try_cmpxchg_release
+#define arch_try_cmpxchg_release(_ptr, _oldp, _new) \
+({ \
+ typeof(*(_ptr)) *___op = (_oldp), ___o = *___op, ___r; \
+ ___r = arch_cmpxchg_release((_ptr), ___o, (_new)); \
+ if (unlikely(___r != ___o)) \
+ *___op = ___r; \
+ likely(___r == ___o); \
+})
+#endif /* arch_try_cmpxchg_release */
+
+#ifndef arch_try_cmpxchg_relaxed
+#define arch_try_cmpxchg_relaxed(_ptr, _oldp, _new) \
+({ \
+ typeof(*(_ptr)) *___op = (_oldp), ___o = *___op, ___r; \
+ ___r = arch_cmpxchg_relaxed((_ptr), ___o, (_new)); \
+ if (unlikely(___r != ___o)) \
+ *___op = ___r; \
+ likely(___r == ___o); \
+})
+#endif /* arch_try_cmpxchg_relaxed */
+
+#else /* arch_try_cmpxchg_relaxed */
+
+#ifndef arch_try_cmpxchg_acquire
+#define arch_try_cmpxchg_acquire(...) \
+ __atomic_op_acquire(arch_try_cmpxchg, __VA_ARGS__)
+#endif
+
+#ifndef arch_try_cmpxchg_release
+#define arch_try_cmpxchg_release(...) \
+ __atomic_op_release(arch_try_cmpxchg, __VA_ARGS__)
+#endif
+
+#ifndef arch_try_cmpxchg
+#define arch_try_cmpxchg(...) \
+ __atomic_op_fence(arch_try_cmpxchg, __VA_ARGS__)
+#endif
+
+#endif /* arch_try_cmpxchg_relaxed */
+
#ifndef arch_atomic_read_acquire
static __always_inline int
arch_atomic_read_acquire(const atomic_t *v)
@@ -2288,4 +2358,4 @@ arch_atomic64_dec_if_positive(atomic64_t
#endif

#endif /* _LINUX_ATOMIC_FALLBACK_H */
-// 90cd26cfd69d2250303d654955a0cc12620fb91b
+// cca554917d7ea73d5e3e7397dd70c484cad9b2c4
--- a/include/linux/atomic-fallback.h
+++ b/include/linux/atomic-fallback.h
@@ -9,9 +9,9 @@
#include <linux/compiler.h>

#ifndef xchg_relaxed
-#define xchg_relaxed xchg
-#define xchg_acquire xchg
-#define xchg_release xchg
+#define xchg_acquire xchg
+#define xchg_release xchg
+#define xchg_relaxed xchg
#else /* xchg_relaxed */

#ifndef xchg_acquire
@@ -32,9 +32,9 @@
#endif /* xchg_relaxed */

#ifndef cmpxchg_relaxed
-#define cmpxchg_relaxed cmpxchg
-#define cmpxchg_acquire cmpxchg
-#define cmpxchg_release cmpxchg
+#define cmpxchg_acquire cmpxchg
+#define cmpxchg_release cmpxchg
+#define cmpxchg_relaxed cmpxchg
#else /* cmpxchg_relaxed */

#ifndef cmpxchg_acquire
@@ -55,9 +55,9 @@
#endif /* cmpxchg_relaxed */

#ifndef cmpxchg64_relaxed
-#define cmpxchg64_relaxed cmpxchg64
-#define cmpxchg64_acquire cmpxchg64
-#define cmpxchg64_release cmpxchg64
+#define cmpxchg64_acquire cmpxchg64
+#define cmpxchg64_release cmpxchg64
+#define cmpxchg64_relaxed cmpxchg64
#else /* cmpxchg64_relaxed */

#ifndef cmpxchg64_acquire
@@ -77,6 +77,76 @@

#endif /* cmpxchg64_relaxed */

+#ifndef try_cmpxchg_relaxed
+#ifdef try_cmpxchg
+#define try_cmpxchg_acquire try_cmpxchg
+#define try_cmpxchg_release try_cmpxchg
+#define try_cmpxchg_relaxed try_cmpxchg
+#endif /* try_cmpxchg */
+
+#ifndef try_cmpxchg
+#define try_cmpxchg(_ptr, _oldp, _new) \
+({ \
+ typeof(*(_ptr)) *___op = (_oldp), ___o = *___op, ___r; \
+ ___r = cmpxchg((_ptr), ___o, (_new)); \
+ if (unlikely(___r != ___o)) \
+ *___op = ___r; \
+ likely(___r == ___o); \
+})
+#endif /* try_cmpxchg */
+
+#ifndef try_cmpxchg_acquire
+#define try_cmpxchg_acquire(_ptr, _oldp, _new) \
+({ \
+ typeof(*(_ptr)) *___op = (_oldp), ___o = *___op, ___r; \
+ ___r = cmpxchg_acquire((_ptr), ___o, (_new)); \
+ if (unlikely(___r != ___o)) \
+ *___op = ___r; \
+ likely(___r == ___o); \
+})
+#endif /* try_cmpxchg_acquire */
+
+#ifndef try_cmpxchg_release
+#define try_cmpxchg_release(_ptr, _oldp, _new) \
+({ \
+ typeof(*(_ptr)) *___op = (_oldp), ___o = *___op, ___r; \
+ ___r = cmpxchg_release((_ptr), ___o, (_new)); \
+ if (unlikely(___r != ___o)) \
+ *___op = ___r; \
+ likely(___r == ___o); \
+})
+#endif /* try_cmpxchg_release */
+
+#ifndef try_cmpxchg_relaxed
+#define try_cmpxchg_relaxed(_ptr, _oldp, _new) \
+({ \
+ typeof(*(_ptr)) *___op = (_oldp), ___o = *___op, ___r; \
+ ___r = cmpxchg_relaxed((_ptr), ___o, (_new)); \
+ if (unlikely(___r != ___o)) \
+ *___op = ___r; \
+ likely(___r == ___o); \
+})
+#endif /* try_cmpxchg_relaxed */
+
+#else /* try_cmpxchg_relaxed */
+
+#ifndef try_cmpxchg_acquire
+#define try_cmpxchg_acquire(...) \
+ __atomic_op_acquire(try_cmpxchg, __VA_ARGS__)
+#endif
+
+#ifndef try_cmpxchg_release
+#define try_cmpxchg_release(...) \
+ __atomic_op_release(try_cmpxchg, __VA_ARGS__)
+#endif
+
+#ifndef try_cmpxchg
+#define try_cmpxchg(...) \
+ __atomic_op_fence(try_cmpxchg, __VA_ARGS__)
+#endif
+
+#endif /* try_cmpxchg_relaxed */
+
#define arch_atomic_read atomic_read
#define arch_atomic_read_acquire atomic_read_acquire

@@ -2522,4 +2592,4 @@ atomic64_dec_if_positive(atomic64_t *v)
#endif

#endif /* _LINUX_ATOMIC_FALLBACK_H */
-// 9d95b56f98d82a2a26c7b79ccdd0c47572d50a6f
+// d78e6c293c661c15188f0ec05bce45188c8d5892
--- a/scripts/atomic/gen-atomic-fallback.sh
+++ b/scripts/atomic/gen-atomic-fallback.sh
@@ -144,15 +144,11 @@ gen_proto_order_variants()
printf "#endif /* ${basename}_relaxed */\n\n"
}

-gen_xchg_fallbacks()
+gen_order_fallbacks()
{
local xchg="$1"; shift
+
cat <<EOF
-#ifndef ${xchg}_relaxed
-#define ${xchg}_relaxed ${xchg}
-#define ${xchg}_acquire ${xchg}
-#define ${xchg}_release ${xchg}
-#else /* ${xchg}_relaxed */

#ifndef ${xchg}_acquire
#define ${xchg}_acquire(...) \\
@@ -169,11 +165,62 @@ cat <<EOF
__atomic_op_fence(${xchg}, __VA_ARGS__)
#endif

-#endif /* ${xchg}_relaxed */
+EOF
+}
+
+gen_xchg_fallbacks()
+{
+ local xchg="$1"; shift
+ printf "#ifndef ${xchg}_relaxed\n"
+
+ gen_basic_fallbacks ${xchg}
+
+ printf "#else /* ${xchg}_relaxed */\n"
+
+ gen_order_fallbacks ${xchg}
+
+ printf "#endif /* ${xchg}_relaxed */\n\n"
+}
+
+gen_try_cmpxchg_fallback()
+{
+ local order="$1"; shift;
+
+cat <<EOF
+#ifndef ${ARCH}try_cmpxchg${order}
+#define ${ARCH}try_cmpxchg${order}(_ptr, _oldp, _new) \\
+({ \\
+ typeof(*(_ptr)) *___op = (_oldp), ___o = *___op, ___r; \\
+ ___r = ${ARCH}cmpxchg${order}((_ptr), ___o, (_new)); \\
+ if (unlikely(___r != ___o)) \\
+ *___op = ___r; \\
+ likely(___r == ___o); \\
+})
+#endif /* ${ARCH}try_cmpxchg${order} */

EOF
}

+gen_try_cmpxchg_fallbacks()
+{
+ printf "#ifndef ${ARCH}try_cmpxchg_relaxed\n"
+ printf "#ifdef ${ARCH}try_cmpxchg\n"
+
+ gen_basic_fallbacks "${ARCH}try_cmpxchg"
+
+ printf "#endif /* ${ARCH}try_cmpxchg */\n\n"
+
+ for order in "" "_acquire" "_release" "_relaxed"; do
+ gen_try_cmpxchg_fallback "${order}"
+ done
+
+ printf "#else /* ${ARCH}try_cmpxchg_relaxed */\n"
+
+ gen_order_fallbacks "${ARCH}try_cmpxchg"
+
+ printf "#endif /* ${ARCH}try_cmpxchg_relaxed */\n\n"
+}
+
cat << EOF
// SPDX-License-Identifier: GPL-2.0

@@ -191,6 +238,8 @@ for xchg in "${ARCH}xchg" "${ARCH}cmpxch
gen_xchg_fallbacks "${xchg}"
done

+gen_try_cmpxchg_fallbacks
+
grep '^[a-z]' "$1" | while read name meta args; do
gen_proto "${meta}" "${name}" "${ARCH}" "atomic" "int" ${args}
done
--- a/scripts/atomic/gen-atomic-instrumented.sh
+++ b/scripts/atomic/gen-atomic-instrumented.sh
@@ -103,14 +103,31 @@ gen_xchg()
local xchg="$1"; shift
local mult="$1"; shift

+ if [ "${xchg%${xchg#try_cmpxchg}}" = "try_cmpxchg" ] ; then
+
cat <<EOF
-#define ${xchg}(ptr, ...) \\
-({ \\
- typeof(ptr) __ai_ptr = (ptr); \\
- instrument_atomic_write(__ai_ptr, ${mult}sizeof(*__ai_ptr)); \\
- arch_${xchg}(__ai_ptr, __VA_ARGS__); \\
+#define ${xchg}(ptr, oldp, ...) \\
+({ \\
+ typeof(ptr) __ai_ptr = (ptr); \\
+ typeof(oldp) __ai_oldp = (oldp); \\
+ instrument_atomic_write(__ai_ptr, ${mult}sizeof(*__ai_ptr)); \\
+ instrument_atomic_write(__ai_oldp, ${mult}sizeof(*__ai_oldp)); \\
+ arch_${xchg}(__ai_ptr, __ai_oldp, __VA_ARGS__); \\
})
EOF
+
+ else
+
+cat <<EOF
+#define ${xchg}(ptr, ...) \\
+({ \\
+ typeof(ptr) __ai_ptr = (ptr); \\
+ instrument_atomic_write(__ai_ptr, ${mult}sizeof(*__ai_ptr)); \\
+ arch_${xchg}(__ai_ptr, __VA_ARGS__); \\
+})
+EOF
+
+ fi
}

gen_optional_xchg()
@@ -160,7 +177,7 @@ grep '^[a-z]' "$1" | while read name met
gen_proto "${meta}" "${name}" "atomic64" "s64" ${args}
done

-for xchg in "xchg" "cmpxchg" "cmpxchg64"; do
+for xchg in "xchg" "cmpxchg" "cmpxchg64" "try_cmpxchg"; do
for order in "" "_acquire" "_release" "_relaxed"; do
gen_optional_xchg "${xchg}" "${order}"
done