[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, 10 insertions, 15 deletions

diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c
index 7ee120e85913..3d036cdfae41 100644
--- a/net/sctp/protocol.c
+++ b/net/sctp/protocol.c
@@ -224,7 +224,7 @@ int sctp_copy_local_addr_list(struct sctp_bind_addr *bp, sctp_scope_t scope,
                               (copy_flags & SCTP_ADDR6_ALLOWED) &&
                               (copy_flags & SCTP_ADDR6_PEERSUPP)))) {
                                 error = sctp_add_bind_addr(bp, &addr->a, 1,
-                                                           GFP_ATOMIC);
+                                                    GFP_ATOMIC);
                                 if (error)
                                         goto end_copy;
                         }
@@ -428,9 +428,7 @@ static struct dst_entry *sctp_v4_get_dst(struct sctp_association *asoc,
         struct rtable *rt;
         struct flowi fl;
         struct sctp_bind_addr *bp;
-        rwlock_t *addr_lock;
         struct sctp_sockaddr_entry *laddr;
-        struct list_head *pos;
         struct dst_entry *dst = NULL;
         union sctp_addr dst_saddr;
 
@@ -459,23 +457,20 @@ static struct dst_entry *sctp_v4_get_dst(struct sctp_association *asoc,
                 goto out;
 
         bp = &asoc->base.bind_addr;
-        addr_lock = &asoc->base.addr_lock;
 
         if (dst) {
                 /* Walk through the bind address list and look for a bind
                  * address that matches the source address of the returned dst.
                  */
-                sctp_read_lock(addr_lock);
-                list_for_each(pos, &bp->address_list) {
-                        laddr = list_entry(pos, struct sctp_sockaddr_entry,
-                                           list);
-                        if (!laddr->use_as_src)
+                rcu_read_lock();
+                list_for_each_entry_rcu(laddr, &bp->address_list, list) {
+                        if (!laddr->valid || !laddr->use_as_src)
                                 continue;
                         sctp_v4_dst_saddr(&dst_saddr, dst, htons(bp->port));
                         if (sctp_v4_cmp_addr(&dst_saddr, &laddr->a))
                                 goto out_unlock;
                 }
-                sctp_read_unlock(addr_lock);
+                rcu_read_unlock();
 
                 /* None of the bound addresses match the source address of the
                  * dst. So release it.
@@ -487,10 +482,10 @@ static struct dst_entry *sctp_v4_get_dst(struct sctp_association *asoc,
         /* Walk through the bind address list and try to get a dst that
          * matches a bind address as the source address.
          */
-        sctp_read_lock(addr_lock);
-        list_for_each(pos, &bp->address_list) {
-                laddr = list_entry(pos, struct sctp_sockaddr_entry, list);
-
+        rcu_read_lock();
+        list_for_each_entry_rcu(laddr, &bp->address_list, list) {
+                if (!laddr->valid)
+                        continue;
                 if ((laddr->use_as_src) &&
                     (AF_INET == laddr->a.sa.sa_family)) {
                         fl.fl4_src = laddr->a.v4.sin_addr.s_addr;
@@ -502,7 +497,7 @@ static struct dst_entry *sctp_v4_get_dst(struct sctp_association *asoc,
         }
 
 out_unlock:
-        sctp_read_unlock(addr_lock);
+        rcu_read_unlock();
 out:
         if (dst)
                 SCTP_DEBUG_PRINTK("rt_dst:%u.%u.%u.%u, rt_src:%u.%u.%u.%u\n",