X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=include%2Fasm-generic%2Flocal.h;fp=include%2Fasm-generic%2Flocal.h;h=16fc00360f7582eef14a9934c9d6fe7f3abf7f7c;hb=64ba3f394c830ec48a1c31b53dcae312c56f1604;hp=ab469297272c1da3e8cee1d77a6ab5f70a2805fc;hpb=be1e6109ac94a859551f8e1774eb9a8469fe055c;p=linux-2.6.git

diff --git a/include/asm-generic/local.h b/include/asm-generic/local.h
index ab4692972..16fc00360 100644
--- a/include/asm-generic/local.h
+++ b/include/asm-generic/local.h
@@ -1,37 +1,31 @@
 #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. */
@@ -40,6 +34,68 @@ typedef struct
 #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.