IPoIB/cm: Optimize stale connection detection

In the presence of some running RX connections, we repeat
queue_delayed_work calls each 4 RX WRs, which is a waste.  It's enough
to start stale task when a first passive connection is added, and
rerun it every IPOIB_CM_RX_DELAY as long as there are outstanding
passive connections.

This removes some code from RX data path.

Signed-off-by: Michael S. Tsirkin <mst@dev.mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

diff --git a/drivers/infiniband/ulp/ipoib/ipoib_cm.c b/drivers/infiniband/ulp/ipoib/ipoib_cm.c
index 785bc85..eec833b 100644 (file)
--- a/drivers/infiniband/ulp/ipoib/ipoib_cm.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_cm.c
@@ -257,10 +257,11 @@ static int ipoib_cm_req_handler(struct ib_cm_id *cm_id, struct ib_cm_event *even
        cm_id->context = p;
        p->jiffies = jiffies;
        spin_lock_irq(&priv->lock);
+       if (list_empty(&priv->cm.passive_ids))
+               queue_delayed_work(ipoib_workqueue,
+                                  &priv->cm.stale_task, IPOIB_CM_RX_DELAY);
        list_add(&p->list, &priv->cm.passive_ids);
        spin_unlock_irq(&priv->lock);
-       queue_delayed_work(ipoib_workqueue,
-                          &priv->cm.stale_task, IPOIB_CM_RX_DELAY);
        return 0;
 
 err_rep:
@@ -378,8 +379,6 @@ void ipoib_cm_handle_rx_wc(struct net_device *dev, struct ib_wc *wc)
                        if (!list_empty(&p->list))
                                list_move(&p->list, &priv->cm.passive_ids);
                        spin_unlock_irqrestore(&priv->lock, flags);
-                       queue_delayed_work(ipoib_workqueue,
-                                          &priv->cm.stale_task, IPOIB_CM_RX_DELAY);
                }
        }
 
@@ -1100,6 +1099,10 @@ static void ipoib_cm_stale_task(struct work_struct *work)
                kfree(p);
                spin_lock_irq(&priv->lock);
        }
+
+       if (!list_empty(&priv->cm.passive_ids))
+               queue_delayed_work(ipoib_workqueue,
+                                  &priv->cm.stale_task, IPOIB_CM_RX_DELAY);
        spin_unlock_irq(&priv->lock);
 }