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authorDmitry Torokhov <dmitry.torokhov@gmail.com>2017-05-30 05:54:21 +0300
committerDmitry Torokhov <dmitry.torokhov@gmail.com>2017-05-30 05:54:21 +0300
commitd8f797c60661a90ee26ca9330cf85ede9aa2ec17 (patch)
tree5038609885fc3e4cb7f329d974875ac4411c6af5 /include/linux/refcount.h
parent8fd708157a592a376c4d0b3b2ba23b9e9f79caa5 (diff)
parent5ed02dbb497422bf225783f46e6eadd237d23d6b (diff)
downloadlinux-d8f797c60661a90ee26ca9330cf85ede9aa2ec17.tar.xz
Merge tag 'v4.12-rc3' into next
Sync with mainline to bring in changes in platform drovers dropping calls to sparse_keymap_free() so that we can remove it for good.
Diffstat (limited to 'include/linux/refcount.h')
-rw-r--r--include/linux/refcount.h19
1 files changed, 19 insertions, 0 deletions
diff --git a/include/linux/refcount.h b/include/linux/refcount.h
index 0023fee4bbbc..b34aa649d204 100644
--- a/include/linux/refcount.h
+++ b/include/linux/refcount.h
@@ -6,17 +6,36 @@
#include <linux/spinlock.h>
#include <linux/kernel.h>
+/**
+ * refcount_t - variant of atomic_t specialized for reference counts
+ * @refs: atomic_t counter field
+ *
+ * The counter saturates at UINT_MAX and will not move once
+ * there. This avoids wrapping the counter and causing 'spurious'
+ * use-after-free bugs.
+ */
typedef struct refcount_struct {
atomic_t refs;
} refcount_t;
#define REFCOUNT_INIT(n) { .refs = ATOMIC_INIT(n), }
+/**
+ * refcount_set - set a refcount's value
+ * @r: the refcount
+ * @n: value to which the refcount will be set
+ */
static inline void refcount_set(refcount_t *r, unsigned int n)
{
atomic_set(&r->refs, n);
}
+/**
+ * refcount_read - get a refcount's value
+ * @r: the refcount
+ *
+ * Return: the refcount's value
+ */
static inline unsigned int refcount_read(const refcount_t *r)
{
return atomic_read(&r->refs);