[SCTP]: Convert bind_addr_list locking to RCU

Since the sctp_sockaddr_entry is now RCU enabled as part of
the patch to synchronize sctp_localaddr_list, it makes sense to
change all handling of these entries to RCU.  This includes the
sctp_bind_addrs structure and it's list of bound addresses.

This list is currently protected by an external rw_lock and that
looks like an overkill.  There are only 2 writers to the list:
bind()/bindx() calls, and BH processing of ASCONF-ACK chunks.
These are already seriealized via the socket lock, so they will
not step on each other.  These are also relatively rare, so we
should be good with RCU.

The readers are varied and they are easily converted to RCU.

Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Sridhar Samdurala <sri@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 6 insertions, 12 deletions

diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c
index 79856c924525..2e34220d94cd 100644
--- a/net/sctp/sm_make_chunk.c
+++ b/net/sctp/sm_make_chunk.c
@@ -1531,7 +1531,7 @@ no_hmac:
 	/* Also, add the destination address. */
 	if (list_empty(&retval->base.bind_addr.address_list)) {
 		sctp_add_bind_addr(&retval->base.bind_addr, &chunk->dest, 1,
-				   GFP_ATOMIC);
+				GFP_ATOMIC);
 	}
 
 	retval->next_tsn = retval->c.initial_tsn;
@@ -2613,22 +2613,16 @@ static int sctp_asconf_param_success(struct sctp_association *asoc,
 
 	switch (asconf_param->param_hdr.type) {
 	case SCTP_PARAM_ADD_IP:
-		sctp_local_bh_disable();
-		sctp_write_lock(&asoc->base.addr_lock);
-		list_for_each(pos, &bp->address_list) {
-			saddr = list_entry(pos, struct sctp_sockaddr_entry, list);
+		/* This is always done in BH context with a socket lock
+		 * held, so the list can not change.
+		 */
+		list_for_each_entry(saddr, &bp->address_list, list) {
 			if (sctp_cmp_addr_exact(&saddr->a, &addr))
 				saddr->use_as_src = 1;
 		}
-		sctp_write_unlock(&asoc->base.addr_lock);
-		sctp_local_bh_enable();
 		break;
 	case SCTP_PARAM_DEL_IP:
-		sctp_local_bh_disable();
-		sctp_write_lock(&asoc->base.addr_lock);
-		retval = sctp_del_bind_addr(bp, &addr);
-		sctp_write_unlock(&asoc->base.addr_lock);
-		sctp_local_bh_enable();
+		retval = sctp_del_bind_addr(bp, &addr, call_rcu_bh);
 		list_for_each(pos, &asoc->peer.transport_addr_list) {
 			transport = list_entry(pos, struct sctp_transport,
 						 transports);