Patch "rds: tcp: atomically purge entries from rds_tcp_conn_list during netns delete" has been added to the 4.14-stable tree

This is a note to let you know that I've just added the patch titled

rds: tcp: atomically purge entries from rds_tcp_conn_list during netns delete

to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
rds-tcp-atomically-purge-entries-from-rds_tcp_conn_list-during-netns-delete.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Sowmini Varadhan <[email protected]>
Date: Thu, 30 Nov 2017 11:11:29 -0800
Subject: rds: tcp: atomically purge entries from rds_tcp_conn_list during netns delete

From: Sowmini Varadhan <[email protected]>

commit f10b4cff98c6977668434fbf5dd58695eeca2897 upstream.

The rds_tcp_kill_sock() function parses the rds_tcp_conn_list to find the rds_connection entries marked for deletion as part of the netns deletion under the protection of the rds_tcp_conn_lock. Since the rds_tcp_conn_list tracks rds_tcp_connections (which have a 1:1 mapping with rds_conn_path), multiple tc entries in the rds_tcp_conn_list will map to a single rds_connection, and will be deleted as part of the rds_conn_destroy() operation that is done outside the rds_tcp_conn_lock.

The rds_tcp_conn_list traversal done under the protection of rds_tcp_conn_lock should not leave any doomed tc entries in the list after the rds_tcp_conn_lock is released, else another concurrently executiong netns delete (for a differnt netns) thread may trip on these entries.

---
 net/rds/tcp.c |    9 +++++++--
 net/rds/tcp.h |    1 +
 2 files changed, 8 insertions(+), 2 deletions(-)

@@ -306,7 +306,8 @@ static void rds_tcp_conn_free(void *arg)
 	rdsdebug("freeing tc %p\n", tc);
 
 	spin_lock_irqsave(&rds_tcp_conn_lock, flags);
-	list_del(&tc->t_tcp_node);
+	if (!tc->t_tcp_node_detached)
+		list_del(&tc->t_tcp_node);
 	spin_unlock_irqrestore(&rds_tcp_conn_lock, flags);
 
 	kmem_cache_free(rds_tcp_conn_slab, tc);

@@ -531,8 +532,12 @@ static void rds_tcp_kill_sock(struct net
 
 		if (net != c_net || !tc->t_sock)
 			continue;
-		if (!list_has_conn(&tmp_list, tc->t_cpath->cp_conn))
+		if (!list_has_conn(&tmp_list, tc->t_cpath->cp_conn)) {
 			list_move_tail(&tc->t_tcp_node, &tmp_list);
+		} else {
+			list_del(&tc->t_tcp_node);
+			tc->t_tcp_node_detached = true;
+		}
 	}
 	spin_unlock_irq(&rds_tcp_conn_lock);
 	list_for_each_entry_safe(tc, _tc, &tmp_list, t_tcp_node) {

@@ -12,6 +12,7 @@ struct rds_tcp_incoming {
 struct rds_tcp_connection {
 
 	struct list_head	t_tcp_node;
+	bool			t_tcp_node_detached;
 	struct rds_conn_path	*t_cpath;
 	/* t_conn_path_lock synchronizes the connection establishment between
 	 * rds_tcp_accept_one and rds_tcp_conn_path_connect

Patches currently in stable-queue which might be from [email protected] are

queue-4.14/rds-tcp-atomically-purge-entries-from-rds_tcp_conn_list-during-netns-delete.patch queue-4.14/rds-tcp-correctly-sequence-cleanup-on-netns-deletion.patch