locking/refcount: Add refcount_t API kernel-doc comments

Signed-off-by: David Windsor <dwindsor@gmail.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: elena.reshetova@intel.com
Cc: kernel-hardening@lists.openwall.com
Link: http://lkml.kernel.org/r/1489160052-20293-1-git-send-email-dwindsor@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

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);