[PATCH -v2 23/33] locking,tile: Implement atomic{,64}_fetch_{add,sub,and,or,xor}()

From: Peter Zijlstra
Date: Tue May 31 2016 - 06:36:00 EST

Implement FETCH-OP atomic primitives, these are very similar to the
existing OP-RETURN primitives we already have, except they return the
value of the atomic variable _before_ modification.

This is especially useful for irreversible operations -- such as
bitops (because it becomes impossible to reconstruct the state prior
to modification).

Acked-by: Chris Metcalf <cmetcalf@xxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
---
arch/tile/include/asm/atomic.h | 4 +
arch/tile/include/asm/atomic_32.h | 60 +++++++++++++------
arch/tile/include/asm/atomic_64.h | 115 +++++++++++++++++++++++++-------------
arch/tile/include/asm/bitops_32.h | 18 ++---
arch/tile/lib/atomic_32.c | 42 ++++++-------
arch/tile/lib/atomic_asm_32.S | 14 ++--
6 files changed, 159 insertions(+), 94 deletions(-)

--- a/arch/tile/include/asm/atomic.h
+++ b/arch/tile/include/asm/atomic.h
@@ -46,6 +46,10 @@ static inline int atomic_read(const atom
*/
#define atomic_sub_return(i, v) atomic_add_return((int)(-(i)), (v))

+#define atomic_fetch_sub(i, v) atomic_fetch_add(-(int)(i), (v))
+
+#define atomic_fetch_or atomic_fetch_or
+
/**
* atomic_sub - subtract integer from atomic variable
* @i: integer value to subtract
--- a/arch/tile/include/asm/atomic_32.h
+++ b/arch/tile/include/asm/atomic_32.h
@@ -34,18 +34,29 @@ static inline void atomic_add(int i, ato
_atomic_xchg_add(&v->counter, i);
}

-#define ATOMIC_OP(op) \
-unsigned long _atomic_##op(volatile unsigned long *p, unsigned long mask); \
+#define ATOMIC_OPS(op) \
+unsigned long _atomic_fetch_##op(volatile unsigned long *p, unsigned long mask); \
static inline void atomic_##op(int i, atomic_t *v) \
{ \
- _atomic_##op((unsigned long *)&v->counter, i); \
+ _atomic_fetch_##op((unsigned long *)&v->counter, i); \
+} \
+static inline int atomic_fetch_##op(int i, atomic_t *v) \
+{ \
+ smp_mb(); \
+ return _atomic_fetch_##op((unsigned long *)&v->counter, i); \
}

-ATOMIC_OP(and)
-ATOMIC_OP(or)
-ATOMIC_OP(xor)
+ATOMIC_OPS(and)
+ATOMIC_OPS(or)
+ATOMIC_OPS(xor)
+
+#undef ATOMIC_OPS

-#undef ATOMIC_OP
+static inline int atomic_fetch_add(int i, atomic_t *v)
+{
+ smp_mb();
+ return _atomic_xchg_add(&v->counter, i);
+}

/**
* atomic_add_return - add integer and return
@@ -126,17 +137,30 @@ static inline void atomic64_add(long lon
_atomic64_xchg_add(&v->counter, i);
}

-#define ATOMIC64_OP(op) \
-long long _atomic64_##op(long long *v, long long n); \
+#define ATOMIC64_OPS(op) \
+long long _atomic64_fetch_##op(long long *v, long long n); \
+static inline void atomic64_##op(long long i, atomic64_t *v) \
+{ \
+ _atomic64_fetch_##op(&v->counter, i); \
+} \
static inline void atomic64_##op(long long i, atomic64_t *v) \
{ \
- _atomic64_##op(&v->counter, i); \
+ smp_mb(); \
+ return _atomic64_fetch_##op(&v->counter, i); \
}

ATOMIC64_OP(and)
ATOMIC64_OP(or)
ATOMIC64_OP(xor)

+#undef ATOMIC64_OPS
+
+static inline long long atomic64_fetch_add(long long i, atomic64_t *v)
+{
+ smp_mb();
+ return _atomic64_xchg_add(&v->counter, i);
+}
+
/**
* atomic64_add_return - add integer and return
* @v: pointer of type atomic64_t
@@ -186,6 +210,7 @@ static inline void atomic64_set(atomic64
#define atomic64_inc_return(v) atomic64_add_return(1LL, (v))
#define atomic64_inc_and_test(v) (atomic64_inc_return(v) == 0)
#define atomic64_sub_return(i, v) atomic64_add_return(-(i), (v))
+#define atomic64_fetch_sub(i, v) atomic64_fetch_add(-(i), (v))
#define atomic64_sub_and_test(a, v) (atomic64_sub_return((a), (v)) == 0)
#define atomic64_sub(i, v) atomic64_add(-(i), (v))
#define atomic64_dec(v) atomic64_sub(1LL, (v))
@@ -193,7 +218,6 @@ static inline void atomic64_set(atomic64
#define atomic64_dec_and_test(v) (atomic64_dec_return((v)) == 0)
#define atomic64_inc_not_zero(v) atomic64_add_unless((v), 1LL, 0LL)

-
#endif /* !__ASSEMBLY__ */

/*
@@ -248,10 +272,10 @@ extern struct __get_user __atomic_xchg(v
extern struct __get_user __atomic_xchg_add(volatile int *p, int *lock, int n);
extern struct __get_user __atomic_xchg_add_unless(volatile int *p,
int *lock, int o, int n);
-extern struct __get_user __atomic_or(volatile int *p, int *lock, int n);
-extern struct __get_user __atomic_and(volatile int *p, int *lock, int n);
-extern struct __get_user __atomic_andn(volatile int *p, int *lock, int n);
-extern struct __get_user __atomic_xor(volatile int *p, int *lock, int n);
+extern struct __get_user __atomic_fetch_or(volatile int *p, int *lock, int n);
+extern struct __get_user __atomic_fetch_and(volatile int *p, int *lock, int n);
+extern struct __get_user __atomic_fetch_andn(volatile int *p, int *lock, int n);
+extern struct __get_user __atomic_fetch_xor(volatile int *p, int *lock, int n);
extern long long __atomic64_cmpxchg(volatile long long *p, int *lock,
long long o, long long n);
extern long long __atomic64_xchg(volatile long long *p, int *lock, long long n);
@@ -259,9 +283,9 @@ extern long long __atomic64_xchg_add(vol
long long n);
extern long long __atomic64_xchg_add_unless(volatile long long *p,
int *lock, long long o, long long n);
-extern long long __atomic64_and(volatile long long *p, int *lock, long long n);
-extern long long __atomic64_or(volatile long long *p, int *lock, long long n);
-extern long long __atomic64_xor(volatile long long *p, int *lock, long long n);
+extern long long __atomic64_fetch_and(volatile long long *p, int *lock, long long n);
+extern long long __atomic64_fetch_or(volatile long long *p, int *lock, long long n);
+extern long long __atomic64_fetch_xor(volatile long long *p, int *lock, long long n);

/* Return failure from the atomic wrappers. */
struct __get_user __atomic_bad_address(int __user *addr);
--- a/arch/tile/include/asm/atomic_64.h
+++ b/arch/tile/include/asm/atomic_64.h
@@ -32,11 +32,6 @@
* on any routine which updates memory and returns a value.
*/

-static inline void atomic_add(int i, atomic_t *v)
-{
- __insn_fetchadd4((void *)&v->counter, i);
-}
-
/*
* Note a subtlety of the locking here. We are required to provide a
* full memory barrier before and after the operation. However, we
@@ -59,28 +54,39 @@ static inline int atomic_add_return(int
return val;
}

-static inline int __atomic_add_unless(atomic_t *v, int a, int u)
+#define ATOMIC_OPS(op) \
+static inline int atomic_fetch_##op(int i, atomic_t *v) \
+{ \
+ int val; \
+ smp_mb(); \
+ val = __insn_fetch##op##4((void *)&v->counter, i); \
+ smp_mb(); \
+ return val; \
+} \
+static inline void atomic_##op(int i, atomic_t *v) \
+{ \
+ __insn_fetch##op##4((void *)&v->counter, i); \
+}
+
+ATOMIC_OPS(add)
+ATOMIC_OPS(and)
+ATOMIC_OPS(or)
+
+#undef ATOMIC_OPS
+
+static inline int atomic_fetch_xor(int i, atomic_t *v)
{
int guess, oldval = v->counter;
+ smp_mb();
do {
- if (oldval == u)
- break;
guess = oldval;
- oldval = cmpxchg(&v->counter, guess, guess + a);
+ __insn_mtspr(SPR_CMPEXCH_VALUE, guess);
+ oldval = __insn_cmpexch4(&v->counter, guess ^ i);
} while (guess != oldval);
+ smp_mb();
return oldval;
}

-static inline void atomic_and(int i, atomic_t *v)
-{
- __insn_fetchand4((void *)&v->counter, i);
-}
-
-static inline void atomic_or(int i, atomic_t *v)
-{
- __insn_fetchor4((void *)&v->counter, i);
-}
-
static inline void atomic_xor(int i, atomic_t *v)
{
int guess, oldval = v->counter;
@@ -91,6 +97,18 @@ static inline void atomic_xor(int i, ato
} while (guess != oldval);
}

+static inline int __atomic_add_unless(atomic_t *v, int a, int u)
+{
+ int guess, oldval = v->counter;
+ do {
+ if (oldval == u)
+ break;
+ guess = oldval;
+ oldval = cmpxchg(&v->counter, guess, guess + a);
+ } while (guess != oldval);
+ return oldval;
+}
+
/* Now the true 64-bit operations. */

#define ATOMIC64_INIT(i) { (i) }
@@ -98,11 +116,6 @@ static inline void atomic_xor(int i, ato
#define atomic64_read(v) READ_ONCE((v)->counter)
#define atomic64_set(v, i) WRITE_ONCE((v)->counter, (i))

-static inline void atomic64_add(long i, atomic64_t *v)
-{
- __insn_fetchadd((void *)&v->counter, i);
-}
-
static inline long atomic64_add_return(long i, atomic64_t *v)
{
int val;
@@ -112,26 +125,37 @@ static inline long atomic64_add_return(l
return val;
}

-static inline long atomic64_add_unless(atomic64_t *v, long a, long u)
+#define ATOMIC64_OPS(op) \
+static inline long atomic64_fetch_##op(long i, atomic64_t *v) \
+{ \
+ long val; \
+ smp_mb(); \
+ val = __insn_fetch##op((void *)&v->counter, i); \
+ smp_mb(); \
+ return val; \
+} \
+static inline void atomic64_##op(long i, atomic64_t *v) \
+{ \
+ __insn_fetch##op((void *)&v->counter, i); \
+}
+
+ATOMIC64_OPS(add)
+ATOMIC64_OPS(and)
+ATOMIC64_OPS(or)
+
+#undef ATOMIC64_OPS
+
+static inline long atomic64_fetch_xor(long i, atomic64_t *v)
{
long guess, oldval = v->counter;
+ smp_mb();
do {
- if (oldval == u)
- break;
guess = oldval;
- oldval = cmpxchg(&v->counter, guess, guess + a);
+ __insn_mtspr(SPR_CMPEXCH_VALUE, guess);
+ oldval = __insn_cmpexch(&v->counter, guess ^ i);
} while (guess != oldval);
- return oldval != u;
-}
-
-static inline void atomic64_and(long i, atomic64_t *v)
-{
- __insn_fetchand((void *)&v->counter, i);
-}
-
-static inline void atomic64_or(long i, atomic64_t *v)
-{
- __insn_fetchor((void *)&v->counter, i);
+ smp_mb();
+ return oldval;
}

static inline void atomic64_xor(long i, atomic64_t *v)
@@ -144,7 +168,20 @@ static inline void atomic64_xor(long i,
} while (guess != oldval);
}

+static inline long atomic64_add_unless(atomic64_t *v, long a, long u)
+{
+ long guess, oldval = v->counter;
+ do {
+ if (oldval == u)
+ break;
+ guess = oldval;
+ oldval = cmpxchg(&v->counter, guess, guess + a);
+ } while (guess != oldval);
+ return oldval != u;
+}
+
#define atomic64_sub_return(i, v) atomic64_add_return(-(i), (v))
+#define atomic64_fetch_sub(i, v) atomic64_fetch_add(-(i), (v))
#define atomic64_sub(i, v) atomic64_add(-(i), (v))
#define atomic64_inc_return(v) atomic64_add_return(1, (v))
#define atomic64_dec_return(v) atomic64_sub_return(1, (v))
--- a/arch/tile/include/asm/bitops_32.h
+++ b/arch/tile/include/asm/bitops_32.h
@@ -19,9 +19,9 @@
#include <asm/barrier.h>

/* Tile-specific routines to support <asm/bitops.h>. */
-unsigned long _atomic_or(volatile unsigned long *p, unsigned long mask);
-unsigned long _atomic_andn(volatile unsigned long *p, unsigned long mask);
-unsigned long _atomic_xor(volatile unsigned long *p, unsigned long mask);
+unsigned long _atomic_fetch_or(volatile unsigned long *p, unsigned long mask);
+unsigned long _atomic_fetch_andn(volatile unsigned long *p, unsigned long mask);
+unsigned long _atomic_fetch_xor(volatile unsigned long *p, unsigned long mask);

/**
* set_bit - Atomically set a bit in memory
@@ -35,7 +35,7 @@ unsigned long _atomic_xor(volatile unsig
*/
static inline void set_bit(unsigned nr, volatile unsigned long *addr)
{
- _atomic_or(addr + BIT_WORD(nr), BIT_MASK(nr));
+ _atomic_fetch_or(addr + BIT_WORD(nr), BIT_MASK(nr));
}

/**
@@ -54,7 +54,7 @@ static inline void set_bit(unsigned nr,
*/
static inline void clear_bit(unsigned nr, volatile unsigned long *addr)
{
- _atomic_andn(addr + BIT_WORD(nr), BIT_MASK(nr));
+ _atomic_fetch_andn(addr + BIT_WORD(nr), BIT_MASK(nr));
}

/**
@@ -69,7 +69,7 @@ static inline void clear_bit(unsigned nr
*/
static inline void change_bit(unsigned nr, volatile unsigned long *addr)
{
- _atomic_xor(addr + BIT_WORD(nr), BIT_MASK(nr));
+ _atomic_fetch_xor(addr + BIT_WORD(nr), BIT_MASK(nr));
}

/**
@@ -85,7 +85,7 @@ static inline int test_and_set_bit(unsig
unsigned long mask = BIT_MASK(nr);
addr += BIT_WORD(nr);
smp_mb(); /* barrier for proper semantics */
- return (_atomic_or(addr, mask) & mask) != 0;
+ return (_atomic_fetch_or(addr, mask) & mask) != 0;
}

/**
@@ -101,7 +101,7 @@ static inline int test_and_clear_bit(uns
unsigned long mask = BIT_MASK(nr);
addr += BIT_WORD(nr);
smp_mb(); /* barrier for proper semantics */
- return (_atomic_andn(addr, mask) & mask) != 0;
+ return (_atomic_fetch_andn(addr, mask) & mask) != 0;
}

/**
@@ -118,7 +118,7 @@ static inline int test_and_change_bit(un
unsigned long mask = BIT_MASK(nr);
addr += BIT_WORD(nr);
smp_mb(); /* barrier for proper semantics */
- return (_atomic_xor(addr, mask) & mask) != 0;
+ return (_atomic_fetch_xor(addr, mask) & mask) != 0;
}

#include <asm-generic/bitops/ext2-atomic.h>
--- a/arch/tile/lib/atomic_32.c
+++ b/arch/tile/lib/atomic_32.c
@@ -88,29 +88,29 @@ int _atomic_cmpxchg(int *v, int o, int n
}
EXPORT_SYMBOL(_atomic_cmpxchg);

-unsigned long _atomic_or(volatile unsigned long *p, unsigned long mask)
+unsigned long _atomic_fetch_or(volatile unsigned long *p, unsigned long mask)
{
- return __atomic_or((int *)p, __atomic_setup(p), mask).val;
+ return __atomic_fetch_or((int *)p, __atomic_setup(p), mask).val;
}
-EXPORT_SYMBOL(_atomic_or);
+EXPORT_SYMBOL(_atomic_fetch_or);

-unsigned long _atomic_and(volatile unsigned long *p, unsigned long mask)
+unsigned long _atomic_fetch_and(volatile unsigned long *p, unsigned long mask)
{
- return __atomic_and((int *)p, __atomic_setup(p), mask).val;
+ return __atomic_fetch_and((int *)p, __atomic_setup(p), mask).val;
}
-EXPORT_SYMBOL(_atomic_and);
+EXPORT_SYMBOL(_atomic_fetch_and);

-unsigned long _atomic_andn(volatile unsigned long *p, unsigned long mask)
+unsigned long _atomic_fetch_andn(volatile unsigned long *p, unsigned long mask)
{
- return __atomic_andn((int *)p, __atomic_setup(p), mask).val;
+ return __atomic_fetch_andn((int *)p, __atomic_setup(p), mask).val;
}
-EXPORT_SYMBOL(_atomic_andn);
+EXPORT_SYMBOL(_atomic_fetch_andn);

-unsigned long _atomic_xor(volatile unsigned long *p, unsigned long mask)
+unsigned long _atomic_fetch_xor(volatile unsigned long *p, unsigned long mask)
{
- return __atomic_xor((int *)p, __atomic_setup(p), mask).val;
+ return __atomic_fetch_xor((int *)p, __atomic_setup(p), mask).val;
}
-EXPORT_SYMBOL(_atomic_xor);
+EXPORT_SYMBOL(_atomic_fetch_xor);


long long _atomic64_xchg(long long *v, long long n)
@@ -142,23 +142,23 @@ long long _atomic64_cmpxchg(long long *v
}
EXPORT_SYMBOL(_atomic64_cmpxchg);

-long long _atomic64_and(long long *v, long long n)
+long long _atomic64_fetch_and(long long *v, long long n)
{
- return __atomic64_and(v, __atomic_setup(v), n);
+ return __atomic64_fetch_and(v, __atomic_setup(v), n);
}
-EXPORT_SYMBOL(_atomic64_and);
+EXPORT_SYMBOL(_atomic64_fetch_and);

-long long _atomic64_or(long long *v, long long n)
+long long _atomic64_fetch_or(long long *v, long long n)
{
- return __atomic64_or(v, __atomic_setup(v), n);
+ return __atomic64_fetch_or(v, __atomic_setup(v), n);
}
-EXPORT_SYMBOL(_atomic64_or);
+EXPORT_SYMBOL(_atomic64_fetch_or);

-long long _atomic64_xor(long long *v, long long n)
+long long _atomic64_fetch_xor(long long *v, long long n)
{
- return __atomic64_xor(v, __atomic_setup(v), n);
+ return __atomic64_fetch_xor(v, __atomic_setup(v), n);
}
-EXPORT_SYMBOL(_atomic64_xor);
+EXPORT_SYMBOL(_atomic64_fetch_xor);

/*
* If any of the atomic or futex routines hit a bad address (not in
--- a/arch/tile/lib/atomic_asm_32.S
+++ b/arch/tile/lib/atomic_asm_32.S
@@ -177,10 +177,10 @@ atomic_op _xchg, 32, "move r24, r2"
atomic_op _xchg_add, 32, "add r24, r22, r2"
atomic_op _xchg_add_unless, 32, \
"sne r26, r22, r2; { bbns r26, 3f; add r24, r22, r3 }"
-atomic_op _or, 32, "or r24, r22, r2"
-atomic_op _and, 32, "and r24, r22, r2"
-atomic_op _andn, 32, "nor r2, r2, zero; and r24, r22, r2"
-atomic_op _xor, 32, "xor r24, r22, r2"
+atomic_op _fetch_or, 32, "or r24, r22, r2"
+atomic_op _fetch_and, 32, "and r24, r22, r2"
+atomic_op _fetch_andn, 32, "nor r2, r2, zero; and r24, r22, r2"
+atomic_op _fetch_xor, 32, "xor r24, r22, r2"

atomic_op 64_cmpxchg, 64, "{ seq r26, r22, r2; seq r27, r23, r3 }; \
{ bbns r26, 3f; move r24, r4 }; { bbns r27, 3f; move r25, r5 }"
@@ -192,9 +192,9 @@ atomic_op 64_xchg_add_unless, 64, \
{ bbns r26, 3f; add r24, r22, r4 }; \
{ bbns r27, 3f; add r25, r23, r5 }; \
slt_u r26, r24, r22; add r25, r25, r26"
-atomic_op 64_or, 64, "{ or r24, r22, r2; or r25, r23, r3 }"
-atomic_op 64_and, 64, "{ and r24, r22, r2; and r25, r23, r3 }"
-atomic_op 64_xor, 64, "{ xor r24, r22, r2; xor r25, r23, r3 }"
+atomic_op 64_fetch_or, 64, "{ or r24, r22, r2; or r25, r23, r3 }"
+atomic_op 64_fetch_and, 64, "{ and r24, r22, r2; and r25, r23, r3 }"
+atomic_op 64_fetch_xor, 64, "{ xor r24, r22, r2; xor r25, r23, r3 }"

jrp lr /* happy backtracer */