Merge remote-tracking branch 'torvalds/master' into perf-tools-next

To pick up fixes sent via perf-tools, by Namhyung Kim.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 17 insertions, 1 deletions

diff --git a/net/unix/garbage.c b/net/unix/garbage.c
index fa39b6265238..6433a414acf8 100644
--- a/net/unix/garbage.c
+++ b/net/unix/garbage.c
@@ -274,11 +274,22 @@ static void __unix_gc(struct work_struct *work)
 	 * receive queues.  Other, non candidate sockets _can_ be
 	 * added to queue, so we must make sure only to touch
 	 * candidates.
+	 *
+	 * Embryos, though never candidates themselves, affect which
+	 * candidates are reachable by the garbage collector.  Before
+	 * being added to a listener's queue, an embryo may already
+	 * receive data carrying SCM_RIGHTS, potentially making the
+	 * passed socket a candidate that is not yet reachable by the
+	 * collector.  It becomes reachable once the embryo is
+	 * enqueued.  Therefore, we must ensure that no SCM-laden
+	 * embryo appears in a (candidate) listener's queue between
+	 * consecutive scan_children() calls.
 	 */
 	list_for_each_entry_safe(u, next, &gc_inflight_list, link) {
+		struct sock *sk = &u->sk;
 		long total_refs;
 
-		total_refs = file_count(u->sk.sk_socket->file);
+		total_refs = file_count(sk->sk_socket->file);
 
 		WARN_ON_ONCE(!u->inflight);
 		WARN_ON_ONCE(total_refs < u->inflight);
@@ -286,6 +297,11 @@ static void __unix_gc(struct work_struct *work)
 			list_move_tail(&u->link, &gc_candidates);
 			__set_bit(UNIX_GC_CANDIDATE, &u->gc_flags);
 			__set_bit(UNIX_GC_MAYBE_CYCLE, &u->gc_flags);
+
+			if (sk->sk_state == TCP_LISTEN) {
+				unix_state_lock(sk);
+				unix_state_unlock(sk);
+			}
 		}
 	}