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locking/atomic, arch/avr32: 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>
Acked-by: Hans-Christian Noren Egtvedt <egtvedt@samfundet.no>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Haavard Skinnemoen <hskinnemoen@gmail.com>
Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no>
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
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra 2016-04-18 01:16:08 +02:00 committed by Ingo Molnar
parent 2efe95fe69
commit 1a6eafacd4
1 changed files with 51 additions and 5 deletions
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56
arch/avr32/include/asm/atomic.h
View File

@ -41,21 +41,51 @@ static inline int __atomic_##op##_return(int i, atomic_t *v) \
return result; \
}
#define ATOMIC_FETCH_OP(op, asm_op, asm_con) \
static inline int __atomic_fetch_##op(int i, atomic_t *v) \
{ \
int result, val; \
\
asm volatile( \
"/* atomic_fetch_" #op " */\n" \
"1: ssrf 5\n" \
" ld.w %0, %3\n" \
" mov %1, %0\n" \
" " #asm_op " %1, %4\n" \
" stcond %2, %1\n" \
" brne 1b" \
: "=&r" (result), "=&r" (val), "=o" (v->counter) \
: "m" (v->counter), #asm_con (i) \
: "cc"); \
\
return result; \
}
ATOMIC_OP_RETURN(sub, sub, rKs21)
ATOMIC_OP_RETURN(add, add, r)
ATOMIC_FETCH_OP (sub, sub, rKs21)
ATOMIC_FETCH_OP (add, add, r)
#define ATOMIC_OP(op, asm_op) \
#define atomic_fetch_or atomic_fetch_or
#define ATOMIC_OPS(op, asm_op) \
ATOMIC_OP_RETURN(op, asm_op, r) \
static inline void atomic_##op(int i, atomic_t *v) \
{ \
(void)__atomic_##op##_return(i, v); \
} \
ATOMIC_FETCH_OP(op, asm_op, r) \
static inline int atomic_fetch_##op(int i, atomic_t *v) \
{ \
return __atomic_fetch_##op(i, v); \
}
ATOMIC_OP(and, and)
ATOMIC_OP(or, or)
ATOMIC_OP(xor, eor)
ATOMIC_OPS(and, and)
ATOMIC_OPS(or, or)
ATOMIC_OPS(xor, eor)
#undef ATOMIC_OP
#undef ATOMIC_OPS
#undef ATOMIC_FETCH_OP
#undef ATOMIC_OP_RETURN
/*
@ -87,6 +117,14 @@ static inline int atomic_add_return(int i, atomic_t *v)
return __atomic_add_return(i, v);
}
static inline int atomic_fetch_add(int i, atomic_t *v)
{
if (IS_21BIT_CONST(i))
return __atomic_fetch_sub(-i, v);
return __atomic_fetch_add(i, v);
}
/*
* atomic_sub_return - subtract the atomic variable
* @i: integer value to subtract
@ -102,6 +140,14 @@ static inline int atomic_sub_return(int i, atomic_t *v)
return __atomic_add_return(-i, v);
}
static inline int atomic_fetch_sub(int i, atomic_t *v)
{
if (IS_21BIT_CONST(i))
return __atomic_fetch_sub(i, v);
return __atomic_fetch_add(-i, v);
}
/*
* __atomic_add_unless - add unless the number is a given value
* @v: pointer of type atomic_t