[PATCHv2 04/16] atomics/treewide: make atomic_fetch_add_unless() optional

From: Mark Rutland
Date: Tue May 29 2018 - 11:48:28 EST

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Several architectures these have a near-identical implementation based
on atomic_read() and atomic_cmpxchg() that we can instead define in
<linux/atomic.h>, so let's do so, using something close to the existing
x86 implementation with try_cmpxchg().

Where an architecture provides its own atomic_fetch_add_unless(), it
must define a preprocessor symbol for it. The instrumented atomics are
updated accordingly.

Note that arch/arc's existing atomic_fetch_add_unless() had redundant
barriers, as these are already present in its atomic_cmpxchg()
implementation.

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

Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx>
Reviewed-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Acked-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Boqun Feng <boqun.feng@xxxxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: Vineet Gupta <vgupta@xxxxxxxxxxxx>
---
arch/alpha/include/asm/atomic.h | 2 +-
arch/arc/include/asm/atomic.h | 28 ----------------------------
arch/arm/include/asm/atomic.h | 11 +----------
arch/arm64/include/asm/atomic.h | 1 -
arch/h8300/include/asm/atomic.h | 1 +
arch/hexagon/include/asm/atomic.h | 1 +
arch/ia64/include/asm/atomic.h | 16 ----------------
arch/m68k/include/asm/atomic.h | 15 ---------------
arch/mips/include/asm/atomic.h | 24 ------------------------
arch/parisc/include/asm/atomic.h | 24 ------------------------
arch/powerpc/include/asm/atomic.h | 1 +
arch/riscv/include/asm/atomic.h | 1 +
arch/s390/include/asm/atomic.h | 15 ---------------
arch/sh/include/asm/atomic.h | 25 -------------------------
arch/sparc/include/asm/atomic_32.h | 2 ++
arch/sparc/include/asm/atomic_64.h | 15 ---------------
arch/x86/include/asm/atomic.h | 21 ---------------------
arch/xtensa/include/asm/atomic.h | 24 ------------------------
include/asm-generic/atomic-instrumented.h | 4 +++-
include/asm-generic/atomic.h | 11 -----------
include/linux/atomic.h | 23 +++++++++++++++++++++++
21 files changed, 34 insertions(+), 231 deletions(-)

diff --git a/arch/alpha/include/asm/atomic.h b/arch/alpha/include/asm/atomic.h
index eb0f25e4c5dd..4a800a3424a3 100644
--- a/arch/alpha/include/asm/atomic.h
+++ b/arch/alpha/include/asm/atomic.h
@@ -235,7 +235,7 @@ static __inline__ int atomic_fetch_add_unless(atomic_t *v, int a, int u)
smp_mb();
return old;
}
-
+#define atomic_fetch_add_unless atomic_fetch_add_unless

/**
* atomic64_add_unless - add unless the number is a given value
diff --git a/arch/arc/include/asm/atomic.h b/arch/arc/include/asm/atomic.h
index 1406825b5e7d..60da80481c5d 100644
--- a/arch/arc/include/asm/atomic.h
+++ b/arch/arc/include/asm/atomic.h
@@ -308,34 +308,6 @@ ATOMIC_OPS(xor, ^=, CTOP_INST_AXOR_DI_R2_R2_R3)
#undef ATOMIC_OP_RETURN
#undef ATOMIC_OP

-/**
- * atomic_fetch_add_unless - add unless the number is a given value
- * @v: pointer of type atomic_t
- * @a: the amount to add to v...
- * @u: ...unless v is equal to u.
- *
- * Atomically adds @a to @v, so long as it was not @u.
- * Returns the old value of @v
- */
-#define atomic_fetch_add_unless(v, a, u) \
-({ \
- int c, old; \
- \
- /* \
- * Explicit full memory barrier needed before/after as \
- * LLOCK/SCOND thmeselves don't provide any such semantics \
- */ \
- smp_mb(); \
- \
- c = atomic_read(v); \
- while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c)\
- c = old; \
- \
- smp_mb(); \
- \
- c; \
-})
-
#define atomic_inc(v) atomic_add(1, v)
#define atomic_dec(v) atomic_sub(1, v)

diff --git a/arch/arm/include/asm/atomic.h b/arch/arm/include/asm/atomic.h
index 02f3894faa48..74460aa00fa0 100644
--- a/arch/arm/include/asm/atomic.h
+++ b/arch/arm/include/asm/atomic.h
@@ -156,6 +156,7 @@ static inline int atomic_fetch_add_unless(atomic_t *v, int a, int u)

return oldval;
}
+#define atomic_fetch_add_unless atomic_fetch_add_unless

#else /* ARM_ARCH_6 */

@@ -215,16 +216,6 @@ static inline int atomic_cmpxchg(atomic_t *v, int old, int new)
return ret;
}

-static inline int atomic_fetch_add_unless(atomic_t *v, int a, int u)
-{
- int c, old;
-
- c = atomic_read(v);
- while (c != u && (old = atomic_cmpxchg((v), c, c + a)) != c)
- c = old;
- return c;
-}
-
#endif /* __LINUX_ARM_ARCH__ */

#define ATOMIC_OPS(op, c_op, asm_op) \
diff --git a/arch/arm64/include/asm/atomic.h b/arch/arm64/include/asm/atomic.h
index ad50412889c5..22c8c43d6689 100644
--- a/arch/arm64/include/asm/atomic.h
+++ b/arch/arm64/include/asm/atomic.h
@@ -125,7 +125,6 @@
#define atomic_dec_and_test(v) (atomic_dec_return(v) == 0)
#define atomic_sub_and_test(i, v) (atomic_sub_return((i), (v)) == 0)
#define atomic_add_negative(i, v) (atomic_add_return((i), (v)) < 0)
-#define atomic_fetch_add_unless(v, a, u) ___atomic_add_unless(v, a, u,)
#define atomic_andnot atomic_andnot

/*
diff --git a/arch/h8300/include/asm/atomic.h b/arch/h8300/include/asm/atomic.h
index 4465cfc30a3a..250bb3baac23 100644
--- a/arch/h8300/include/asm/atomic.h
+++ b/arch/h8300/include/asm/atomic.h
@@ -106,5 +106,6 @@ static inline int atomic_fetch_add_unless(atomic_t *v, int a, int u)
arch_local_irq_restore(flags);
return ret;
}
+#define atomic_fetch_add_unless atomic_fetch_add_unless

#endif /* __ARCH_H8300_ATOMIC __ */
diff --git a/arch/hexagon/include/asm/atomic.h b/arch/hexagon/include/asm/atomic.h
index d2feeba93c44..86c67e9adbfa 100644
--- a/arch/hexagon/include/asm/atomic.h
+++ b/arch/hexagon/include/asm/atomic.h
@@ -196,6 +196,7 @@ static inline int atomic_fetch_add_unless(atomic_t *v, int a, int u)
);
return __oldval;
}
+#define atomic_fetch_add_unless atomic_fetch_add_unless

#define atomic_inc(v) atomic_add(1, (v))
#define atomic_dec(v) atomic_sub(1, (v))
diff --git a/arch/ia64/include/asm/atomic.h b/arch/ia64/include/asm/atomic.h
index 93d48b823220..cfe44086338e 100644
--- a/arch/ia64/include/asm/atomic.h
+++ b/arch/ia64/include/asm/atomic.h
@@ -215,22 +215,6 @@ ATOMIC64_FETCH_OP(xor, ^)
(cmpxchg(&((v)->counter), old, new))
#define atomic64_xchg(v, new) (xchg(&((v)->counter), new))

-static __inline__ int atomic_fetch_add_unless(atomic_t *v, int a, int u)
-{
- int c, old;
- c = atomic_read(v);
- for (;;) {
- if (unlikely(c == (u)))
- break;
- old = atomic_cmpxchg((v), c, c + (a));
- if (likely(old == c))
- break;
- c = old;
- }
- return c;
-}
-
-
static __inline__ long atomic64_add_unless(atomic64_t *v, long a, long u)
{
long c, old;
diff --git a/arch/m68k/include/asm/atomic.h b/arch/m68k/include/asm/atomic.h
index 8022d9ea1213..596882cda224 100644
--- a/arch/m68k/include/asm/atomic.h
+++ b/arch/m68k/include/asm/atomic.h
@@ -211,19 +211,4 @@ static inline int atomic_add_negative(int i, atomic_t *v)
return c != 0;
}

-static __inline__ int atomic_fetch_add_unless(atomic_t *v, int a, int u)
-{
- int c, old;
- c = atomic_read(v);
- for (;;) {
- if (unlikely(c == (u)))
- break;
- old = atomic_cmpxchg((v), c, c + (a));
- if (likely(old == c))
- break;
- c = old;
- }
- return c;
-}
-
#endif /* __ARCH_M68K_ATOMIC __ */
diff --git a/arch/mips/include/asm/atomic.h b/arch/mips/include/asm/atomic.h
index 502e691c6393..794734e730d9 100644
--- a/arch/mips/include/asm/atomic.h
+++ b/arch/mips/include/asm/atomic.h
@@ -274,30 +274,6 @@ static __inline__ int atomic_sub_if_positive(int i, atomic_t * v)
#define atomic_cmpxchg(v, o, n) (cmpxchg(&((v)->counter), (o), (n)))
#define atomic_xchg(v, new) (xchg(&((v)->counter), (new)))

-/**
- * atomic_fetch_add_unless - add unless the number is a given value
- * @v: pointer of type atomic_t
- * @a: the amount to add to v...
- * @u: ...unless v is equal to u.
- *
- * Atomically adds @a to @v, so long as it was not @u.
- * Returns the old value of @v.
- */
-static __inline__ int atomic_fetch_add_unless(atomic_t *v, int a, int u)
-{
- int c, old;
- c = atomic_read(v);
- for (;;) {
- if (unlikely(c == (u)))
- break;
- old = atomic_cmpxchg((v), c, c + (a));
- if (likely(old == c))
- break;
- c = old;
- }
- return c;
-}
-
#define atomic_dec_return(v) atomic_sub_return(1, (v))
#define atomic_inc_return(v) atomic_add_return(1, (v))

diff --git a/arch/parisc/include/asm/atomic.h b/arch/parisc/include/asm/atomic.h
index 3fd0243bf405..b2b6261d05e7 100644
--- a/arch/parisc/include/asm/atomic.h
+++ b/arch/parisc/include/asm/atomic.h
@@ -77,30 +77,6 @@ static __inline__ int atomic_read(const atomic_t *v)
#define atomic_cmpxchg(v, o, n) (cmpxchg(&((v)->counter), (o), (n)))
#define atomic_xchg(v, new) (xchg(&((v)->counter), new))

-/**
- * atomic_fetch_add_unless - add unless the number is a given value
- * @v: pointer of type atomic_t
- * @a: the amount to add to v...
- * @u: ...unless v is equal to u.
- *
- * Atomically adds @a to @v, so long as it was not @u.
- * Returns the old value of @v.
- */
-static __inline__ int atomic_fetch_add_unless(atomic_t *v, int a, int u)
-{
- int c, old;
- c = atomic_read(v);
- for (;;) {
- if (unlikely(c == (u)))
- break;
- old = atomic_cmpxchg((v), c, c + (a));
- if (likely(old == c))
- break;
- c = old;
- }
- return c;
-}
-
#define ATOMIC_OP(op, c_op) \
static __inline__ void atomic_##op(int i, atomic_t *v) \
{ \
diff --git a/arch/powerpc/include/asm/atomic.h b/arch/powerpc/include/asm/atomic.h
index e59620ee4f6b..b5646c079c16 100644
--- a/arch/powerpc/include/asm/atomic.h
+++ b/arch/powerpc/include/asm/atomic.h
@@ -248,6 +248,7 @@ static __inline__ int atomic_fetch_add_unless(atomic_t *v, int a, int u)

return t;
}
+#define atomic_fetch_add_unless atomic_fetch_add_unless

/**
* atomic_inc_not_zero - increment unless the number is zero
diff --git a/arch/riscv/include/asm/atomic.h b/arch/riscv/include/asm/atomic.h
index 18259e90f57e..5f161daefcd2 100644
--- a/arch/riscv/include/asm/atomic.h
+++ b/arch/riscv/include/asm/atomic.h
@@ -349,6 +349,7 @@ static __always_inline int atomic_fetch_add_unless(atomic_t *v, int a, int u)
: "memory");
return prev;
}
+#define atomic_fetch_add_unless atomic_fetch_add_unless

#ifndef CONFIG_GENERIC_ATOMIC64
static __always_inline long __atomic64_add_unless(atomic64_t *v, long a, long u)
diff --git a/arch/s390/include/asm/atomic.h b/arch/s390/include/asm/atomic.h
index 66dac30a4fe1..26c6b713a7a3 100644
--- a/arch/s390/include/asm/atomic.h
+++ b/arch/s390/include/asm/atomic.h
@@ -90,21 +90,6 @@ static inline int atomic_cmpxchg(atomic_t *v, int old, int new)
return __atomic_cmpxchg(&v->counter, old, new);
}

-static inline int atomic_fetch_add_unless(atomic_t *v, int a, int u)
-{
- int c, old;
- c = atomic_read(v);
- for (;;) {
- if (unlikely(c == u))
- break;
- old = atomic_cmpxchg(v, c, c + a);
- if (likely(old == c))
- break;
- c = old;
- }
- return c;
-}
-
#define ATOMIC64_INIT(i) { (i) }

static inline long atomic64_read(const atomic64_t *v)
diff --git a/arch/sh/include/asm/atomic.h b/arch/sh/include/asm/atomic.h
index ef45931ebac5..422fac764ca1 100644
--- a/arch/sh/include/asm/atomic.h
+++ b/arch/sh/include/asm/atomic.h
@@ -45,31 +45,6 @@
#define atomic_xchg(v, new) (xchg(&((v)->counter), new))
#define atomic_cmpxchg(v, o, n) (cmpxchg(&((v)->counter), (o), (n)))

-/**
- * atomic_fetch_add_unless - add unless the number is a given value
- * @v: pointer of type atomic_t
- * @a: the amount to add to v...
- * @u: ...unless v is equal to u.
- *
- * Atomically adds @a to @v, so long as it was not @u.
- * Returns the old value of @v.
- */
-static inline int atomic_fetch_add_unless(atomic_t *v, int a, int u)
-{
- int c, old;
- c = atomic_read(v);
- for (;;) {
- if (unlikely(c == (u)))
- break;
- old = atomic_cmpxchg((v), c, c + (a));
- if (likely(old == c))
- break;
- c = old;
- }
-
- return c;
-}
-
#endif /* CONFIG_CPU_J2 */

#endif /* __ASM_SH_ATOMIC_H */
diff --git a/arch/sparc/include/asm/atomic_32.h b/arch/sparc/include/asm/atomic_32.h
index a58f4b43bcc7..9d7a15acc0c5 100644
--- a/arch/sparc/include/asm/atomic_32.h
+++ b/arch/sparc/include/asm/atomic_32.h
@@ -30,6 +30,8 @@ int atomic_xchg(atomic_t *, int);
int atomic_fetch_add_unless(atomic_t *, int, int);
void atomic_set(atomic_t *, int);

+#define atomic_fetch_add_unless atomic_fetch_add_unless
+
#define atomic_set_release(v, i) atomic_set((v), (i))

#define atomic_read(v) READ_ONCE((v)->counter)
diff --git a/arch/sparc/include/asm/atomic_64.h b/arch/sparc/include/asm/atomic_64.h
index 07830a316464..e4f1c93db31f 100644
--- a/arch/sparc/include/asm/atomic_64.h
+++ b/arch/sparc/include/asm/atomic_64.h
@@ -89,21 +89,6 @@ static inline int atomic_xchg(atomic_t *v, int new)
return xchg(&v->counter, new);
}

-static inline int atomic_fetch_add_unless(atomic_t *v, int a, int u)
-{
- int c, old;
- c = atomic_read(v);
- for (;;) {
- if (unlikely(c == (u)))
- break;
- old = atomic_cmpxchg((v), c, c + (a));
- if (likely(old == c))
- break;
- c = old;
- }
- return c;
-}
-
#define atomic64_cmpxchg(v, o, n) \
((__typeof__((v)->counter))cmpxchg(&((v)->counter), (o), (n)))
#define atomic64_xchg(v, new) (xchg(&((v)->counter), new))
diff --git a/arch/x86/include/asm/atomic.h b/arch/x86/include/asm/atomic.h
index 84ed0bd76aef..616327ac9d39 100644
--- a/arch/x86/include/asm/atomic.h
+++ b/arch/x86/include/asm/atomic.h
@@ -253,27 +253,6 @@ static inline int arch_atomic_fetch_xor(int i, atomic_t *v)
return val;
}

-/**
- * arch_atomic_fetch_add_unless - add unless the number is already a given value
- * @v: pointer of type atomic_t
- * @a: the amount to add to v...
- * @u: ...unless v is equal to u.
- *
- * Atomically adds @a to @v, so long as @v was not already @u.
- * Returns the old value of @v.
- */
-static __always_inline int arch_atomic_fetch_add_unless(atomic_t *v, int a, int u)
-{
- int c = arch_atomic_read(v);
-
- do {
- if (unlikely(c == u))
- break;
- } while (!arch_atomic_try_cmpxchg(v, &c, c + a));
-
- return c;
-}
-
#ifdef CONFIG_X86_32
# include <asm/atomic64_32.h>
#else
diff --git a/arch/xtensa/include/asm/atomic.h b/arch/xtensa/include/asm/atomic.h
index 4188e56c06c9..f4c9f82c40c6 100644
--- a/arch/xtensa/include/asm/atomic.h
+++ b/arch/xtensa/include/asm/atomic.h
@@ -274,30 +274,6 @@ ATOMIC_OPS(xor)
#define atomic_cmpxchg(v, o, n) ((int)cmpxchg(&((v)->counter), (o), (n)))
#define atomic_xchg(v, new) (xchg(&((v)->counter), new))

-/**
- * atomic_fetch_add_unless - add unless the number is a given value
- * @v: pointer of type atomic_t
- * @a: the amount to add to v...
- * @u: ...unless v is equal to u.
- *
- * Atomically adds @a to @v, so long as it was not @u.
- * Returns the old value of @v.
- */
-static __inline__ int atomic_fetch_add_unless(atomic_t *v, int a, int u)
-{
- int c, old;
- c = atomic_read(v);
- for (;;) {
- if (unlikely(c == (u)))
- break;
- old = atomic_cmpxchg((v), c, c + (a));
- if (likely(old == c))
- break;
- c = old;
- }
- return c;
-}
-
#endif /* __KERNEL__ */

#endif /* _XTENSA_ATOMIC_H */
diff --git a/include/asm-generic/atomic-instrumented.h b/include/asm-generic/atomic-instrumented.h
index 52b7dcb41769..6e0818c182e2 100644
--- a/include/asm-generic/atomic-instrumented.h
+++ b/include/asm-generic/atomic-instrumented.h
@@ -84,12 +84,14 @@ static __always_inline bool atomic64_try_cmpxchg(atomic64_t *v, s64 *old, s64 ne
}
#endif

+#ifdef arch_atomic_fetch_add_unless
+#define atomic_fetch_add_unless atomic_fetch_add_unless
static __always_inline int atomic_fetch_add_unless(atomic_t *v, int a, int u)
{
kasan_check_write(v, sizeof(*v));
return arch_atomic_fetch_add_unless(v, a, u);
}
-
+#endif

static __always_inline bool atomic64_add_unless(atomic64_t *v, s64 a, s64 u)
{
diff --git a/include/asm-generic/atomic.h b/include/asm-generic/atomic.h
index 10051ed6d088..757e45821220 100644
--- a/include/asm-generic/atomic.h
+++ b/include/asm-generic/atomic.h
@@ -221,15 +221,4 @@ static inline void atomic_dec(atomic_t *v)
#define atomic_xchg(ptr, v) (xchg(&(ptr)->counter, (v)))
#define atomic_cmpxchg(v, old, new) (cmpxchg(&((v)->counter), (old), (new)))

-#ifndef atomic_fetch_add_unless
-static inline int atomic_fetch_add_unless(atomic_t *v, int a, int u)
-{
- int c, old;
- c = atomic_read(v);
- while (c != u && (old = atomic_cmpxchg(v, c, c + a)) != c)
- c = old;
- return c;
-}
-#endif
-
#endif /* __ASM_GENERIC_ATOMIC_H */
diff --git a/include/linux/atomic.h b/include/linux/atomic.h
index e83f12ec7f2d..1105c0b37f27 100644
--- a/include/linux/atomic.h
+++ b/include/linux/atomic.h
@@ -520,6 +520,29 @@
#endif /* xchg_relaxed */

/**
+ * atomic_fetch_add_unless - add unless the number is already a given value
+ * @v: pointer of type atomic_t
+ * @a: the amount to add to v...
+ * @u: ...unless v is equal to u.
+ *
+ * Atomically adds @a to @v, so long as @v was not already @u.
+ * Returns original value of @v
+ */
+#ifndef atomic_fetch_add_unless
+static inline int atomic_fetch_add_unless(atomic_t *v, int a, int u)
+{
+ int c = atomic_read(v);
+
+ do {
+ if (unlikely(c == u))
+ break;
+ } while (!atomic_try_cmpxchg(v, &c, c + a));
+
+ return c;
+}
+#endif
+
+/**
* atomic_add_unless - add unless the number is already a given value
* @v: pointer of type atomic_t
* @a: the amount to add to v...
--
2.11.0

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