Changeset 0fad93a in mainline

Timestamp:

2006-02-21T13:18:41Z (19 years ago)

Author:

Jakub Jermar <jakub@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

c2942d8

Parents:

6f8a426

Message:

Add atomic_add() operation for sparc64.

File:

• arch/sparc64/include/atomic.h (modified) (1 diff)

arch/sparc64/include/atomic.h

@@ -34 +34 @@
 typedef struct { volatile __u64 count; } atomic_t;
 
-/*
- * TODO: these are just placeholders for real implementations of atomic_inc and atomic_dec.
- * WARNING: the following functions cause the code to be preemption-unsafe !!!
+/** Atomic add operation.
+ *
+ * Use atomic compare and swap operation to atomically add signed value.
+ *
+ * @param val Atomic variable.
+ * @param i Signed value to be added.
+ *
+ * @return Value of the atomic variable as it existed before addition.
  */
+static inline count_t atomic_add(atomic_t *val, int i)
+{
+        __u64 a, b;
+        volatile __u64 x = (__u64) &val->count;
+
+        __asm__ volatile (
+                "0:\n"
+                "ldx %0, %1\n"
+                "add %1, %3, %2\n"
+                "casx %0, %1, %2\n"
+                "cmp %1, %2\n"
+                "bne 0b\n"
+                "nop\n"
+                : "=m" (*((__u64 *)x)), "=r" (a), "=r" (b)
+                : "r" (i)
+        );
+
+        return a;
+}
 
 static inline void atomic_inc(atomic_t *val)
 {
-        val->count++;
+        (void) atomic_add(val, 1);
 }
 
 static inline void atomic_dec(atomic_t *val)
 {
-        val->count--;
+        (void) atomic_add(val, -1);
 }