tipc: optimize function tipc_node_timeout()

In single-link usage, the function tipc_node_timeout() still iterates
over the whole link array to handle each link. Given that the maximum
number of bearers are 3, there are 2 redundant iterations with lock
grab/release. Since this function is executing very frequently it makes
sense to optimize it.

This commit adds conditional checking to exit from the loop if the
known number of configured links has already been accessed.

Acked-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Tung Nguyen <tung.q.nguyen@dektech.com.au>
Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/tipc/node.c b/net/tipc/node.c
index 6a44eb812baf4a2fe31eeb55b04023f9f402666b..8972ca1c654cbb99160387a1d6d97a96ff81f786 100644 (file)
--- a/net/tipc/node.c
+++ b/net/tipc/node.c
@@ -551,21 +551,23 @@ static void tipc_node_timeout(struct timer_list *t)
        struct tipc_node *n = from_timer(n, t, timer);
        struct tipc_link_entry *le;
        struct sk_buff_head xmitq;
+       int remains = n->link_cnt;
        int bearer_id;
        int rc = 0;
 
        __skb_queue_head_init(&xmitq);
 
-       for (bearer_id = 0; bearer_id < MAX_BEARERS; bearer_id++) {
+       for (bearer_id = 0; remains && (bearer_id < MAX_BEARERS); bearer_id++) {
                tipc_node_read_lock(n);
                le = &n->links[bearer_id];
-               spin_lock_bh(&le->lock);
                if (le->link) {
+                       spin_lock_bh(&le->lock);
                        /* Link tolerance may change asynchronously: */
                        tipc_node_calculate_timer(n, le->link);
                        rc = tipc_link_timeout(le->link, &xmitq);
+                       spin_unlock_bh(&le->lock);
+                       remains--;
                }
-               spin_unlock_bh(&le->lock);
                tipc_node_read_unlock(n);
                tipc_bearer_xmit(n->net, bearer_id, &xmitq, &le->maddr);
                if (rc & TIPC_LINK_DOWN_EVT)