[PATCH] tcp: documents timewait refcnt tricks

Adds kerneldoc for inet_twsk_unhash() & inet_twsk_bind_unhash().

With help from Randy Dunlap.

Suggested-by: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/inet_timewait_sock.c b/net/ipv4/inet_timewait_sock.c
index bf4b1e2..cc94cc2 100644 (file)
--- a/net/ipv4/inet_timewait_sock.c
+++ b/net/ipv4/inet_timewait_sock.c
@@ -15,9 +15,13 @@
 #include <net/ip.h>
 
 
-/*
- * unhash a timewait socket from established hash
- * lock must be hold by caller
+/**
+ *     inet_twsk_unhash - unhash a timewait socket from established hash
+ *     @tw: timewait socket
+ *
+ *     unhash a timewait socket from established hash, if hashed.
+ *     ehash lock must be held by caller.
+ *     Returns 1 if caller should call inet_twsk_put() after lock release.
  */
 int inet_twsk_unhash(struct inet_timewait_sock *tw)
 {
@@ -26,12 +30,21 @@ int inet_twsk_unhash(struct inet_timewait_sock *tw)
 
        hlist_nulls_del_rcu(&tw->tw_node);
        sk_nulls_node_init(&tw->tw_node);
+       /*
+        * We cannot call inet_twsk_put() ourself under lock,
+        * caller must call it for us.
+        */
        return 1;
 }
 
-/*
- * unhash a timewait socket from bind hash
- * lock must be hold by caller
+/**
+ *     inet_twsk_bind_unhash - unhash a timewait socket from bind hash
+ *     @tw: timewait socket
+ *     @hashinfo: hashinfo pointer
+ *
+ *     unhash a timewait socket from bind hash, if hashed.
+ *     bind hash lock must be held by caller.
+ *     Returns 1 if caller should call inet_twsk_put() after lock release.
  */
 int inet_twsk_bind_unhash(struct inet_timewait_sock *tw,
                          struct inet_hashinfo *hashinfo)
@@ -44,6 +57,10 @@ int inet_twsk_bind_unhash(struct inet_timewait_sock *tw,
        __hlist_del(&tw->tw_bind_node);
        tw->tw_tb = NULL;
        inet_bind_bucket_destroy(hashinfo->bind_bucket_cachep, tb);
+       /*
+        * We cannot call inet_twsk_put() ourself under lock,
+        * caller must call it for us.
+        */
        return 1;
 }
 
@@ -139,7 +156,7 @@ void __inet_twsk_hashdance(struct inet_timewait_sock *tw, struct sock *sk,
 
        /*
         * Notes :
-        * - We initially set tw_refcnt to 0 in inet_twsk_alloc()
+        * - We initially set tw_refcnt to 0 in inet_twsk_alloc()
         * - We add one reference for the bhash link
         * - We add one reference for the ehash link
         * - We want this refcnt update done before allowing other
@@ -149,7 +166,6 @@ void __inet_twsk_hashdance(struct inet_timewait_sock *tw, struct sock *sk,
 
        spin_unlock(lock);
 }
-
 EXPORT_SYMBOL_GPL(__inet_twsk_hashdance);
 
 struct inet_timewait_sock *inet_twsk_alloc(const struct sock *sk, const int state)
@@ -190,7 +206,6 @@ struct inet_timewait_sock *inet_twsk_alloc(const struct sock *sk, const int stat
 
        return tw;
 }
-
 EXPORT_SYMBOL_GPL(inet_twsk_alloc);
 
 /* Returns non-zero if quota exceeded.  */
@@ -269,7 +284,6 @@ void inet_twdr_hangman(unsigned long data)
 out:
        spin_unlock(&twdr->death_lock);
 }
-
 EXPORT_SYMBOL_GPL(inet_twdr_hangman);
 
 void inet_twdr_twkill_work(struct work_struct *work)
@@ -300,7 +314,6 @@ void inet_twdr_twkill_work(struct work_struct *work)
                spin_unlock_bh(&twdr->death_lock);
        }
 }
-
 EXPORT_SYMBOL_GPL(inet_twdr_twkill_work);
 
 /* These are always called from BH context.  See callers in
@@ -320,7 +333,6 @@ void inet_twsk_deschedule(struct inet_timewait_sock *tw,
        spin_unlock(&twdr->death_lock);
        __inet_twsk_kill(tw, twdr->hashinfo);
 }
-
 EXPORT_SYMBOL(inet_twsk_deschedule);
 
 void inet_twsk_schedule(struct inet_timewait_sock *tw,
@@ -401,7 +413,6 @@ void inet_twsk_schedule(struct inet_timewait_sock *tw,
                mod_timer(&twdr->tw_timer, jiffies + twdr->period);
        spin_unlock(&twdr->death_lock);
 }
-
 EXPORT_SYMBOL_GPL(inet_twsk_schedule);
 
 void inet_twdr_twcal_tick(unsigned long data)
@@ -462,7 +473,6 @@ out:
 #endif
        spin_unlock(&twdr->death_lock);
 }
-
 EXPORT_SYMBOL_GPL(inet_twdr_twcal_tick);
 
 void inet_twsk_purge(struct inet_hashinfo *hashinfo,