X-Git-Url: http://pilppa.org/gitweb/gitweb.cgi?a=blobdiff_plain;f=net%2Funix%2Fgarbage.c;h=5a0061d6b9bc903bd5f74c789555588634b3da8d;hb=6b41e7dd90c6a628ab5fb8d781302d60a243b2ce;hp=2a27b84f740bc836a8c4d3debb5031209bf8441d;hpb=bc588df79ebfb710abc27342fccf336a68ed1216;p=linux-2.6-omap-h63xx.git

diff --git a/net/unix/garbage.c b/net/unix/garbage.c
index 2a27b84f740..5a0061d6b9b 100644
--- a/net/unix/garbage.c
+++ b/net/unix/garbage.c
@@ -104,8 +104,8 @@ static struct sock *unix_get_socket(struct file *filp)
 	 *	Socket ?
 	 */
 	if (S_ISSOCK(inode->i_mode)) {
-		struct socket * sock = SOCKET_I(inode);
-		struct sock * s = sock->sk;
+		struct socket *sock = SOCKET_I(inode);
+		struct sock *s = sock->sk;
 
 		/*
 		 *	PF_UNIX ?
@@ -124,7 +124,7 @@ static struct sock *unix_get_socket(struct file *filp)
 void unix_inflight(struct file *fp)
 {
 	struct sock *s = unix_get_socket(fp);
-	if(s) {
+	if (s) {
 		struct unix_sock *u = unix_sk(s);
 		spin_lock(&unix_gc_lock);
 		if (atomic_long_inc_return(&u->inflight) == 1) {
@@ -141,7 +141,7 @@ void unix_inflight(struct file *fp)
 void unix_notinflight(struct file *fp)
 {
 	struct sock *s = unix_get_socket(fp);
-	if(s) {
+	if (s) {
 		struct unix_sock *u = unix_sk(s);
 		spin_lock(&unix_gc_lock);
 		BUG_ON(list_empty(&u->link));
@@ -154,7 +154,7 @@ void unix_notinflight(struct file *fp)
 
 static inline struct sk_buff *sock_queue_head(struct sock *sk)
 {
-	return (struct sk_buff *) &sk->sk_receive_queue;
+	return (struct sk_buff *)&sk->sk_receive_queue;
 }
 
 #define receive_queue_for_each_skb(sk, next, skb) \
@@ -186,8 +186,17 @@ static void scan_inflight(struct sock *x, void (*func)(struct unix_sock *),
 				 */
 				struct sock *sk = unix_get_socket(*fp++);
 				if (sk) {
-					hit = true;
-					func(unix_sk(sk));
+					struct unix_sock *u = unix_sk(sk);
+
+					/*
+					 * Ignore non-candidates, they could
+					 * have been added to the queues after
+					 * starting the garbage collection
+					 */
+					if (u->gc_candidate) {
+						hit = true;
+						func(u);
+					}
 				}
 			}
 			if (hit && hitlist != NULL) {
@@ -249,11 +258,11 @@ static void inc_inflight_move_tail(struct unix_sock *u)
 {
 	atomic_long_inc(&u->inflight);
 	/*
-	 * If this is still a candidate, move it to the end of the
-	 * list, so that it's checked even if it was already passed
-	 * over
+	 * If this still might be part of a cycle, move it to the end
+	 * of the list, so that it's checked even if it was already
+	 * passed over
 	 */
-	if (u->gc_candidate)
+	if (u->gc_maybe_cycle)
 		list_move_tail(&u->link, &gc_candidates);
 }
 
@@ -267,6 +276,7 @@ void unix_gc(void)
 	struct unix_sock *next;
 	struct sk_buff_head hitlist;
 	struct list_head cursor;
+	LIST_HEAD(not_cycle_list);
 
 	spin_lock(&unix_gc_lock);
 
@@ -282,10 +292,14 @@ void unix_gc(void)
 	 *
 	 * Holding unix_gc_lock will protect these candidates from
 	 * being detached, and hence from gaining an external
-	 * reference.  This also means, that since there are no
-	 * possible receivers, the receive queues of these sockets are
-	 * static during the GC, even though the dequeue is done
-	 * before the detach without atomicity guarantees.
+	 * reference.  Since there are no possible receivers, all
+	 * buffers currently on the candidates' queues stay there
+	 * during the garbage collection.
+	 *
+	 * We also know that no new candidate can be added onto the
+	 * receive queues.  Other, non candidate sockets _can_ be
+	 * added to queue, so we must make sure only to touch
+	 * candidates.
 	 */
 	list_for_each_entry_safe(u, next, &gc_inflight_list, link) {
 		long total_refs;
@@ -299,6 +313,7 @@ void unix_gc(void)
 		if (total_refs == inflight_refs) {
 			list_move_tail(&u->link, &gc_candidates);
 			u->gc_candidate = 1;
+			u->gc_maybe_cycle = 1;
 		}
 	}
 
@@ -325,13 +340,23 @@ void unix_gc(void)
 		list_move(&cursor, &u->link);
 
 		if (atomic_long_read(&u->inflight) > 0) {
-			list_move_tail(&u->link, &gc_inflight_list);
-			u->gc_candidate = 0;
+			list_move_tail(&u->link, &not_cycle_list);
+			u->gc_maybe_cycle = 0;
 			scan_children(&u->sk, inc_inflight_move_tail, NULL);
 		}
 	}
 	list_del(&cursor);
 
+	/*
+	 * not_cycle_list contains those sockets which do not make up a
+	 * cycle.  Restore these to the inflight list.
+	 */
+	while (!list_empty(&not_cycle_list)) {
+		u = list_entry(not_cycle_list.next, struct unix_sock, link);
+		u->gc_candidate = 0;
+		list_move_tail(&u->link, &gc_inflight_list);
+	}
+
 	/*
 	 * Now gc_candidates contains only garbage.  Restore original
 	 * inflight counters for these as well, and remove the skbuffs
@@ -339,7 +364,7 @@ void unix_gc(void)
 	 */
 	skb_queue_head_init(&hitlist);
 	list_for_each_entry(u, &gc_candidates, link)
-		scan_children(&u->sk, inc_inflight, &hitlist);
+	scan_children(&u->sk, inc_inflight, &hitlist);
 
 	spin_unlock(&unix_gc_lock);