diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2016-04-18 01:16:06 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2016-06-16 10:48:26 +0200 |
| commit | e39d88ea3ce4a471cd0202f4f2c8f5ee0f8d7f53 (patch) | |
| tree | 58c0348f5be7bc46d682d47956b897bce55338ea /arch/m68k | |
| parent | f649370523033c7c2adf16a9d062438c8a7758b3 (diff) | |
locking/atomic, arch/m68k: Implement atomic_fetch_{add,sub,and,or,xor}()
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).
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-m68k@lists.linux-m68k.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/m68k')
| -rw-r--r-- | arch/m68k/include/asm/atomic.h | 53 |
1 files changed, 49 insertions, 4 deletions
diff --git a/arch/m68k/include/asm/atomic.h b/arch/m68k/include/asm/atomic.h index 4858178260f9..5cf9b3b1b6ac 100644 --- a/arch/m68k/include/asm/atomic.h +++ b/arch/m68k/include/asm/atomic.h @@ -38,6 +38,13 @@ static inline void atomic_##op(int i, atomic_t *v) \ #ifdef CONFIG_RMW_INSNS +/* + * Am I reading these CAS loops right in that %2 is the old value and the first + * iteration uses an uninitialized value? + * + * Would it not make sense to add: tmp = atomic_read(v); to avoid this? + */ + #define ATOMIC_OP_RETURN(op, c_op, asm_op) \ static inline int atomic_##op##_return(int i, atomic_t *v) \ { \ @@ -53,6 +60,21 @@ static inline int atomic_##op##_return(int i, atomic_t *v) \ return t; \ } +#define ATOMIC_FETCH_OP(op, c_op, asm_op) \ +static inline int atomic_fetch_##op(int i, atomic_t *v) \ +{ \ + int t, tmp; \ + \ + __asm__ __volatile__( \ + "1: movel %2,%1\n" \ + " " #asm_op "l %3,%1\n" \ + " casl %2,%1,%0\n" \ + " jne 1b" \ + : "+m" (*v), "=&d" (t), "=&d" (tmp) \ + : "g" (i), "2" (atomic_read(v))); \ + return tmp; \ +} + #else #define ATOMIC_OP_RETURN(op, c_op, asm_op) \ @@ -68,20 +90,43 @@ static inline int atomic_##op##_return(int i, atomic_t * v) \ return t; \ } +#define ATOMIC_FETCH_OP(op, c_op, asm_op) \ +static inline int atomic_fetch_##op(int i, atomic_t * v) \ +{ \ + unsigned long flags; \ + int t; \ + \ + local_irq_save(flags); \ + t = v->counter; \ + v->counter c_op i; \ + local_irq_restore(flags); \ + \ + return t; \ +} + #endif /* CONFIG_RMW_INSNS */ #define ATOMIC_OPS(op, c_op, asm_op) \ ATOMIC_OP(op, c_op, asm_op) \ - ATOMIC_OP_RETURN(op, c_op, asm_op) + ATOMIC_OP_RETURN(op, c_op, asm_op) \ + ATOMIC_FETCH_OP(op, c_op, asm_op) ATOMIC_OPS(add, +=, add) ATOMIC_OPS(sub, -=, sub) -ATOMIC_OP(and, &=, and) -ATOMIC_OP(or, |=, or) -ATOMIC_OP(xor, ^=, eor) +#undef ATOMIC_OPS +#define ATOMIC_OPS(op, c_op, asm_op) \ + ATOMIC_OP(op, c_op, asm_op) \ + ATOMIC_FETCH_OP(op, c_op, asm_op) + +#define atomic_fetch_or atomic_fetch_or + +ATOMIC_OPS(and, &=, and) +ATOMIC_OPS(or, |=, or) +ATOMIC_OPS(xor, ^=, eor) #undef ATOMIC_OPS +#undef ATOMIC_FETCH_OP #undef ATOMIC_OP_RETURN #undef ATOMIC_OP |