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DateThu, 14 Oct 2010 22:34:09 +0200
FromPeter Zijlstra <>
Subject[RFC][PATCH 5/7] jump_label: atomic_t interface
Add an interface to allow usage of jump_labels with atomic counters

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
include/linux/jump_label_ref.h | 44 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 44 insertions(+)
Index: linux-2.6/include/linux/jump_label_ref.h
===================================================================
--- /dev/null
+++ linux-2.6/include/linux/jump_label_ref.h
@@ -0,0 +1,44 @@
+#ifndef _LINUX_JUMP_LABEL_REF_H
+#define _LINUX_JUMP_LABEL_REF_H
+
+#include <linux/jump_label.h>
+#include <asm/atomic.h>
+
+#ifdef HAVE_JUMP_LABEL
+
+static inline void jump_label_inc(atomic_t *key)
+{
+ if (atomic_add_return(1, key) == 1)
+ jump_label_enable(key);
+}
+
+static inline void jump_label_dec(atomic_t *key)
+{
+ if (atomic_dec_and_test(key))
+ jump_label_disable(key);
+}
+
+#else /* !HAVE_JUMP_LABEL */
+
+static inline void jump_label_inc(atomic_t *key)
+{
+ atomic_inc(key);
+}
+
+static inline void jump_label_dec(atomic_t *key)
+{
+ atomic_dec(key);
+}
+
+#undef JUMP_LABEL
+#define JUMP_LABEL(key, label) \
+do { \
+ if (unlikely(__builtin_choose_expr( \
+ __builtin_types_compatible_p(typeof(key), atomic_t *), \
+ atomic_read((atomic_t *)(key)), *(key)))) \
+ goto label; \
+} while (0)
+
+#endif /* HAVE_JUMP_LABEL */
+
+#endif /* _LINUX_JUMP_LABEL_REF_H */



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