#ifndef _ASM_GENERIC_LOCAL_H
#define _ASM_GENERIC_LOCAL_H
+#include <linux/config.h>
#include <linux/percpu.h>
#include <linux/hardirq.h>
-#include <asm/atomic.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 atomic_long_t. Which is
- * rather pointless. The whole point behind local_t is that some processors
- * can perform atomic adds and subtracts in a manner which is atomic wrt IRQs
- * running on this CPU. local_t allows exploitation of such capabilities.
- */
+/* An unsigned long type for operations which are atomic for a single
+ * CPU. Usually used in combination with per-cpu variables. */
+#if BITS_PER_LONG == 32
/* Implement in terms of atomics. */
/* Don't use typedef: don't want them to be mixed with atomic_t's. */
typedef struct
{
- atomic_long_t a;
+ atomic_t a;
} local_t;
-#define LOCAL_INIT(i) { ATOMIC_LONG_INIT(i) }
+#define LOCAL_INIT(i) { ATOMIC_INIT(i) }
-#define local_read(l) atomic_long_read(&(l)->a)
-#define local_set(l,i) atomic_long_set((&(l)->a),(i))
-#define local_inc(l) atomic_long_inc(&(l)->a)
-#define local_dec(l) atomic_long_dec(&(l)->a)
-#define local_add(i,l) atomic_long_add((i),(&(l)->a))
-#define local_sub(i,l) atomic_long_sub((i),(&(l)->a))
+#define local_read(l) ((unsigned long)atomic_read(&(l)->a))
+#define local_set(l,i) atomic_set((&(l)->a),(i))
+#define local_inc(l) atomic_inc(&(l)->a)
+#define local_dec(l) atomic_dec(&(l)->a)
+#define local_add(i,l) atomic_add((i),(&(l)->a))
+#define local_sub(i,l) atomic_sub((i),(&(l)->a))
/* Non-atomic variants, ie. preemption disabled and won't be touched
* in interrupt, etc. Some archs can optimize this case well. */
#define __local_add(i,l) local_set((l), local_read(l) + (i))
#define __local_sub(i,l) local_set((l), local_read(l) - (i))
+#else /* ... can't use atomics. */
+/* Implement in terms of three variables.
+ Another option would be to use local_irq_save/restore. */
+
+typedef struct
+{
+ /* 0 = in hardirq, 1 = in softirq, 2 = usermode. */
+ unsigned long v[3];
+} local_t;
+
+#define _LOCAL_VAR(l) ((l)->v[!in_interrupt() + !in_irq()])
+
+#define LOCAL_INIT(i) { { (i), 0, 0 } }
+
+static inline unsigned long local_read(local_t *l)
+{
+ return l->v[0] + l->v[1] + l->v[2];
+}
+
+static inline void local_set(local_t *l, unsigned long v)
+{
+ l->v[0] = v;
+ l->v[1] = l->v[2] = 0;
+}
+
+static inline void local_inc(local_t *l)
+{
+ preempt_disable();
+ _LOCAL_VAR(l)++;
+ preempt_enable();
+}
+
+static inline void local_dec(local_t *l)
+{
+ preempt_disable();
+ _LOCAL_VAR(l)--;
+ preempt_enable();
+}
+
+static inline void local_add(unsigned long v, local_t *l)
+{
+ preempt_disable();
+ _LOCAL_VAR(l) += v;
+ preempt_enable();
+}
+
+static inline void local_sub(unsigned long v, local_t *l)
+{
+ preempt_disable();
+ _LOCAL_VAR(l) -= v;
+ preempt_enable();
+}
+
+/* Non-atomic variants, ie. preemption disabled and won't be touched
+ * in interrupt, etc. Some archs can optimize this case well. */
+#define __local_inc(l) ((l)->v[0]++)
+#define __local_dec(l) ((l)->v[0]--)
+#define __local_add(i,l) ((l)->v[0] += (i))
+#define __local_sub(i,l) ((l)->v[0] -= (i))
+
+#endif /* Non-atomic implementation */
+
/* Use these for per-cpu local_t variables: on some archs they are
* much more efficient than these naive implementations. Note they take
* a variable (eg. mystruct.foo), not an address.