futex: Add some more function commentry

Add some more comments and reformat existing ones to kernel doc style.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Darren Hart <dvhart@linux.intel.com>
Link: http://lkml.kernel.org/r/1464770609-30168-1-git-send-email-bigeasy@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

kernel/futex.c

@@ -381,8 +381,12 @@ static inline int hb_waiters_pending(struct futex_hash_bucket *hb)
 #endif
 }
 
-/*
- * We hash on the keys returned from get_futex_key (see below).
+/**
+ * hash_futex - Return the hash bucket in the global hash
+ * @key:	Pointer to the futex key for which the hash is calculated
+ *
+ * We hash on the keys returned from get_futex_key (see below) and return the
+ * corresponding hash bucket in the global hash.
  */
 static struct futex_hash_bucket *hash_futex(union futex_key *key)
 {
@@ -392,7 +396,12 @@ static struct futex_hash_bucket *hash_futex(union futex_key *key)
 	return &futex_queues[hash & (futex_hashsize - 1)];
 }
 
-/*
+
+/**
+ * match_futex - Check whether two futex keys are equal
+ * @key1:	Pointer to key1
+ * @key2:	Pointer to key2
+ *
  * Return 1 if two futex_keys are equal, 0 otherwise.
  */
 static inline int match_futex(union futex_key *key1, union futex_key *key2)