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| author | Peter Zijlstra <peterz@infradead.org> | 2016-04-18 01:16:03 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2016-06-16 10:48:31 +0200 |
| commit | a8bcccaba162632c3963259b8a442c6b490f4c68 (patch) | |
| tree | d44f5e4ab5ff4f56e444352a18fd00716a69a7af /arch/x86/include/asm/atomic64_32.h | |
| parent | 1af5de9af138941fb8638cf126293b16f3387de4 (diff) | |
| download | linux-0-day-a8bcccaba162632c3963259b8a442c6b490f4c68.tar.gz linux-0-day-a8bcccaba162632c3963259b8a442c6b490f4c68.tar.xz | |
locking/atomic, arch/x86: Implement atomic{,64}_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: 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>
Diffstat (limited to 'arch/x86/include/asm/atomic64_32.h')
| -rw-r--r-- | arch/x86/include/asm/atomic64_32.h | 25 |
1 files changed, 22 insertions, 3 deletions
diff --git a/arch/x86/include/asm/atomic64_32.h b/arch/x86/include/asm/atomic64_32.h index a984111135b16..71d7705fb303b 100644 --- a/arch/x86/include/asm/atomic64_32.h +++ b/arch/x86/include/asm/atomic64_32.h @@ -320,10 +320,29 @@ static inline void atomic64_##op(long long i, atomic64_t *v) \ c = old; \ } -ATOMIC64_OP(and, &) -ATOMIC64_OP(or, |) -ATOMIC64_OP(xor, ^) +#define ATOMIC64_FETCH_OP(op, c_op) \ +static inline long long atomic64_fetch_##op(long long i, atomic64_t *v) \ +{ \ + long long old, c = 0; \ + while ((old = atomic64_cmpxchg(v, c, c c_op i)) != c) \ + c = old; \ + return old; \ +} + +ATOMIC64_FETCH_OP(add, +) + +#define atomic64_fetch_sub(i, v) atomic64_fetch_add(-(i), (v)) + +#define ATOMIC64_OPS(op, c_op) \ + ATOMIC64_OP(op, c_op) \ + ATOMIC64_FETCH_OP(op, c_op) + +ATOMIC64_OPS(and, &) +ATOMIC64_OPS(or, |) +ATOMIC64_OPS(xor, ^) +#undef ATOMIC64_OPS +#undef ATOMIC64_FETCH_OP #undef ATOMIC64_OP #endif /* _ASM_X86_ATOMIC64_32_H */ |