summaryrefslogtreecommitdiff
path: root/include/linux/kref.h
diff options
context:
space:
mode:
authorPeter Zijlstra <a.p.zijlstra@chello.nl>2011-12-13 13:36:20 +0400
committerGreg Kroah-Hartman <gregkh@suse.de>2011-12-13 20:18:25 +0400
commit4af679cd7cbb0a0d8774b5cdb34bffcaa4e86e52 (patch)
treeb97bd32f0af95d22133e98a774966ced2eee0664 /include/linux/kref.h
parent175cad266774d09c57a62c65baa6b4e1edafdf3a (diff)
downloadlinux-4af679cd7cbb0a0d8774b5cdb34bffcaa4e86e52.tar.xz
kref: Inline all functions
These are tiny functions, there's no point in having them out-of-line. Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/n/tip-8eccvi2ur2fzgi00xdjlbf5z@git.kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'include/linux/kref.h')
-rw-r--r--include/linux/kref.h80
1 files changed, 75 insertions, 5 deletions
diff --git a/include/linux/kref.h b/include/linux/kref.h
index d4a62ab2ee5e..1cbae9f2ef77 100644
--- a/include/linux/kref.h
+++ b/include/linux/kref.h
@@ -16,15 +16,85 @@
#define _KREF_H_
#include <linux/types.h>
+#include <linux/slab.h>
struct kref {
atomic_t refcount;
};
-void kref_init(struct kref *kref);
-void kref_get(struct kref *kref);
-int kref_put(struct kref *kref, void (*release) (struct kref *kref));
-int kref_sub(struct kref *kref, unsigned int count,
- void (*release) (struct kref *kref));
+/**
+ * kref_init - initialize object.
+ * @kref: object in question.
+ */
+static inline void kref_init(struct kref *kref)
+{
+ atomic_set(&kref->refcount, 1);
+ smp_mb();
+}
+
+/**
+ * kref_get - increment refcount for object.
+ * @kref: object.
+ */
+static inline void kref_get(struct kref *kref)
+{
+ WARN_ON(!atomic_read(&kref->refcount));
+ atomic_inc(&kref->refcount);
+ smp_mb__after_atomic_inc();
+}
+
+/**
+ * kref_put - decrement refcount for object.
+ * @kref: object.
+ * @release: pointer to the function that will clean up the object when the
+ * last reference to the object is released.
+ * This pointer is required, and it is not acceptable to pass kfree
+ * in as this function.
+ *
+ * Decrement the refcount, and if 0, call release().
+ * Return 1 if the object was removed, otherwise return 0. Beware, if this
+ * function returns 0, you still can not count on the kref from remaining in
+ * memory. Only use the return value if you want to see if the kref is now
+ * gone, not present.
+ */
+static inline int kref_put(struct kref *kref, void (*release)(struct kref *kref))
+{
+ WARN_ON(release == NULL);
+ WARN_ON(release == (void (*)(struct kref *))kfree);
+
+ if (atomic_dec_and_test(&kref->refcount)) {
+ release(kref);
+ return 1;
+ }
+ return 0;
+}
+
+
+/**
+ * kref_sub - subtract a number of refcounts for object.
+ * @kref: object.
+ * @count: Number of recounts to subtract.
+ * @release: pointer to the function that will clean up the object when the
+ * last reference to the object is released.
+ * This pointer is required, and it is not acceptable to pass kfree
+ * in as this function.
+ *
+ * Subtract @count from the refcount, and if 0, call release().
+ * Return 1 if the object was removed, otherwise return 0. Beware, if this
+ * function returns 0, you still can not count on the kref from remaining in
+ * memory. Only use the return value if you want to see if the kref is now
+ * gone, not present.
+ */
+static inline int kref_sub(struct kref *kref, unsigned int count,
+ void (*release)(struct kref *kref))
+{
+ WARN_ON(release == NULL);
+ WARN_ON(release == (void (*)(struct kref *))kfree);
+ if (atomic_sub_and_test((int) count, &kref->refcount)) {
+ release(kref);
+ return 1;
+ }
+ return 0;
+}
#endif /* _KREF_H_ */