arch: Implement local64_t

[sfrench/cifs-2.6.git] / include / asm-generic / local64.h

diff --git a/include/asm-generic/local64.h b/include/asm-generic/local64.h
new file mode 100644 (file)
index 0000000..02ac760
--- /dev/null
+++ b/include/asm-generic/local64.h
@@ -0,0 +1,96 @@
+#ifndef _ASM_GENERIC_LOCAL64_H
+#define _ASM_GENERIC_LOCAL64_H
+
+#include <linux/percpu.h>
+#include <asm/types.h>
+
+/*
+ * A signed long type for operations which are atomic for a single CPU.
+ * Usually used in combination with per-cpu variables.
+ *
+ * This is the default implementation, which uses atomic64_t.  Which is
+ * rather pointless.  The whole point behind local64_t is that some processors
+ * can perform atomic adds and subtracts in a manner which is atomic wrt IRQs
+ * running on this CPU.  local64_t allows exploitation of such capabilities.
+ */
+
+/* Implement in terms of atomics. */
+
+#if BITS_PER_LONG == 64
+
+#include <asm/local.h>
+
+typedef struct {
+       local_t a;
+} local64_t;
+
+#define LOCAL64_INIT(i)        { LOCAL_INIT(i) }
+
+#define local64_read(l)                local_read(&(l)->a)
+#define local64_set(l,i)       local_set((&(l)->a),(i))
+#define local64_inc(l)         local_inc(&(l)->a)
+#define local64_dec(l)         local_dec(&(l)->a)
+#define local64_add(i,l)       local_add((i),(&(l)->a))
+#define local64_sub(i,l)       local_sub((i),(&(l)->a))
+
+#define local64_sub_and_test(i, l) local_sub_and_test((i), (&(l)->a))
+#define local64_dec_and_test(l) local_dec_and_test(&(l)->a)
+#define local64_inc_and_test(l) local_inc_and_test(&(l)->a)
+#define local64_add_negative(i, l) local_add_negative((i), (&(l)->a))
+#define local64_add_return(i, l) local_add_return((i), (&(l)->a))
+#define local64_sub_return(i, l) local_sub_return((i), (&(l)->a))
+#define local64_inc_return(l)  local_inc_return(&(l)->a)
+
+#define local64_cmpxchg(l, o, n) local_cmpxchg((&(l)->a), (o), (n))
+#define local64_xchg(l, n)     local_xchg((&(l)->a), (n))
+#define local64_add_unless(l, _a, u) local_add_unless((&(l)->a), (_a), (u))
+#define local64_inc_not_zero(l)        local_inc_not_zero(&(l)->a)
+
+/* Non-atomic variants, ie. preemption disabled and won't be touched
+ * in interrupt, etc.  Some archs can optimize this case well. */
+#define __local64_inc(l)       local64_set((l), local64_read(l) + 1)
+#define __local64_dec(l)       local64_set((l), local64_read(l) - 1)
+#define __local64_add(i,l)     local64_set((l), local64_read(l) + (i))
+#define __local64_sub(i,l)     local64_set((l), local64_read(l) - (i))
+
+#else /* BITS_PER_LONG != 64 */
+
+#include <asm/atomic.h>
+
+/* Don't use typedef: don't want them to be mixed with atomic_t's. */
+typedef struct {
+       atomic64_t a;
+} local64_t;
+
+#define LOCAL64_INIT(i)        { ATOMIC_LONG_INIT(i) }
+
+#define local64_read(l)                atomic64_read(&(l)->a)
+#define local64_set(l,i)       atomic64_set((&(l)->a),(i))
+#define local64_inc(l)         atomic64_inc(&(l)->a)
+#define local64_dec(l)         atomic64_dec(&(l)->a)
+#define local64_add(i,l)       atomic64_add((i),(&(l)->a))
+#define local64_sub(i,l)       atomic64_sub((i),(&(l)->a))
+
+#define local64_sub_and_test(i, l) atomic64_sub_and_test((i), (&(l)->a))
+#define local64_dec_and_test(l) atomic64_dec_and_test(&(l)->a)
+#define local64_inc_and_test(l) atomic64_inc_and_test(&(l)->a)
+#define local64_add_negative(i, l) atomic64_add_negative((i), (&(l)->a))
+#define local64_add_return(i, l) atomic64_add_return((i), (&(l)->a))
+#define local64_sub_return(i, l) atomic64_sub_return((i), (&(l)->a))
+#define local64_inc_return(l)  atomic64_inc_return(&(l)->a)
+
+#define local64_cmpxchg(l, o, n) atomic64_cmpxchg((&(l)->a), (o), (n))
+#define local64_xchg(l, n)     atomic64_xchg((&(l)->a), (n))
+#define local64_add_unless(l, _a, u) atomic64_add_unless((&(l)->a), (_a), (u))
+#define local64_inc_not_zero(l)        atomic64_inc_not_zero(&(l)->a)
+
+/* Non-atomic variants, ie. preemption disabled and won't be touched
+ * in interrupt, etc.  Some archs can optimize this case well. */
+#define __local64_inc(l)       local64_set((l), local64_read(l) + 1)
+#define __local64_dec(l)       local64_set((l), local64_read(l) - 1)
+#define __local64_add(i,l)     local64_set((l), local64_read(l) + (i))
+#define __local64_sub(i,l)     local64_set((l), local64_read(l) - (i))
+
+#endif /* BITS_PER_LONG != 64 */
+
+#endif /* _ASM_GENERIC_LOCAL64_H */