lockless get_write_access/deny_write_access
new helpers: atomic_inc_unless_negative()/atomic_dec_unless_positive()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/include/linux/atomic.h b/include/linux/atomic.h
index ee456c7..bc6615d 100644
--- a/include/linux/atomic.h
+++ b/include/linux/atomic.h
@@ -34,6 +34,32 @@
}
#endif
+#ifndef atomic_inc_unless_negative
+static inline int atomic_inc_unless_negative(atomic_t *p)
+{
+ int v, v1;
+ for (v = 0; v >= 0; v = v1) {
+ v1 = atomic_cmpxchg(p, v, v + 1);
+ if (likely(v1 == v))
+ return 1;
+ }
+ return 0;
+}
+#endif
+
+#ifndef atomic_dec_unless_positive
+static inline int atomic_dec_unless_positive(atomic_t *p)
+{
+ int v, v1;
+ for (v = 0; v <= 0; v = v1) {
+ v1 = atomic_cmpxchg(p, v, v - 1);
+ if (likely(v1 == v))
+ return 1;
+ }
+ return 0;
+}
+#endif
+
#ifndef CONFIG_ARCH_HAS_ATOMIC_OR
static inline void atomic_or(int i, atomic_t *v)
{