3 files changed, 37 insertions, 1 deletions

diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-netback/common.h
index 0355f8767e3b..bef37be402b8 100644
--- a/drivers/net/xen-netback/common.h
+++ b/drivers/net/xen-netback/common.h
@@ -137,6 +137,8 @@ struct xenvif {
         u16 dealloc_ring[MAX_PENDING_REQS];
         struct task_struct *dealloc_task;
         wait_queue_head_t dealloc_wq;
+        struct timer_list dealloc_delay;
+        bool dealloc_delay_timed_out;
 
         /* Use kthread for guest RX */
         struct task_struct *task;
diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
index 9cc9f638f442..83a71ac5b93a 100644
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -408,6 +408,7 @@ struct xenvif *xenvif_alloc(struct device *parent, domid_t domid,
                           .desc = i };
                 vif->grant_tx_handle[i] = NETBACK_INVALID_HANDLE;
         }
+        init_timer(&vif->dealloc_delay);
 
         /*
          * Initialise a dummy MAC address. We choose the numerically
@@ -556,6 +557,7 @@ void xenvif_disconnect(struct xenvif *vif)
         }
 
         if (vif->dealloc_task) {
+                del_timer_sync(&vif->dealloc_delay);
                 kthread_stop(vif->dealloc_task);
                 vif->dealloc_task = NULL;
         }
diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index 8518a0d1f6f9..bc943205a691 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -133,6 +133,11 @@ static inline pending_ring_idx_t pending_index(unsigned i)
         return i & (MAX_PENDING_REQS-1);
 }
 
+static inline pending_ring_idx_t nr_free_slots(struct xen_netif_tx_back_ring *ring)
+{
+        return ring->nr_ents -  (ring->sring->req_prod - ring->rsp_prod_pvt);
+}
+
 bool xenvif_rx_ring_slots_available(struct xenvif *vif, int needed)
 {
         RING_IDX prod, cons;
@@ -1716,9 +1721,36 @@ static inline int tx_work_todo(struct xenvif *vif)
         return 0;
 }
 
+static void xenvif_dealloc_delay(unsigned long data)
+{
+        struct xenvif *vif = (struct xenvif *)data;
+
+        vif->dealloc_delay_timed_out = true;
+        wake_up(&vif->dealloc_wq);
+}
+
 static inline bool tx_dealloc_work_todo(struct xenvif *vif)
 {
-        return vif->dealloc_cons != vif->dealloc_prod;
+        if (vif->dealloc_cons != vif->dealloc_prod) {
+                if ((nr_free_slots(&vif->tx) > 2 * XEN_NETBK_LEGACY_SLOTS_MAX) &&
+                    (vif->dealloc_prod - vif->dealloc_cons < MAX_PENDING_REQS / 4) &&
+                    !vif->dealloc_delay_timed_out) {
+                        if (!timer_pending(&vif->dealloc_delay)) {
+                                vif->dealloc_delay.function =
+                                        xenvif_dealloc_delay;
+                                vif->dealloc_delay.data = (unsigned long)vif;
+                                mod_timer(&vif->dealloc_delay,
+                                          jiffies + msecs_to_jiffies(1));
+
+                        }
+                        return false;
+                }
+                del_timer_sync(&vif->dealloc_delay);
+                vif->dealloc_delay_timed_out = false;
+                return true;
+        }
+
+        return false;
 }
 
 void xenvif_unmap_frontend_rings(struct xenvif *vif)