sctp: Add RCU protection to assoc->transport_addr_list

peer.transport_addr_list is currently only protected by sk_sock
which is inpractical to acquire for procfs dumping purposes.

This patch adds RCU protection allowing for the procfs readers to
enter RCU read-side critical sections.

Modification of the list continues to be serialized via sk_lock.

V2: Use list_del_rcu() in sctp_association_free() to be safe
    Skip transports marked dead when dumping for procfs

Cc: Vlad Yasevich <vyasevich@gmail.com>
Cc: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Acked-by: Vlad Yasevich <vyasevich@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 3 deletions

diff --git a/net/sctp/associola.c b/net/sctp/associola.c
index ba3f9cc4c047..b45ed1f96921 100644
--- a/net/sctp/associola.c
+++ b/net/sctp/associola.c
@@ -448,7 +448,7 @@ void sctp_association_free(struct sctp_association *asoc)
         /* Release the transport structures. */
         list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
                 transport = list_entry(pos, struct sctp_transport, transports);
-                list_del(pos);
+                list_del_rcu(pos);
                 sctp_transport_free(transport);
         }
 
@@ -568,7 +568,7 @@ void sctp_assoc_rm_peer(struct sctp_association *asoc,
                 sctp_assoc_update_retran_path(asoc);
 
         /* Remove this peer from the list. */
-        list_del(&peer->transports);
+        list_del_rcu(&peer->transports);
 
         /* Get the first transport of asoc. */
         pos = asoc->peer.transport_addr_list.next;
@@ -769,7 +769,7 @@ struct sctp_transport *sctp_assoc_add_peer(struct sctp_association *asoc,
         peer->state = peer_state;
 
         /* Attach the remote transport to our asoc.  */
-        list_add_tail(&peer->transports, &asoc->peer.transport_addr_list);
+        list_add_tail_rcu(&peer->transports, &asoc->peer.transport_addr_list);
         asoc->peer.transport_count++;
 
         /* If we do not yet have a primary path, set one.  */