1 files changed, 46 insertions, 6 deletions

diff --git a/net/core/gro_cells.c b/net/core/gro_cells.c
index e095fb871d91..a725d21159a6 100644
--- a/net/core/gro_cells.c
+++ b/net/core/gro_cells.c
@@ -3,15 +3,18 @@
 #include <linux/slab.h>
 #include <linux/netdevice.h>
 #include <net/gro_cells.h>
+#include <net/hotdata.h>
 
 struct gro_cell {
 	struct sk_buff_head	napi_skbs;
 	struct napi_struct	napi;
+	local_lock_t		bh_lock;
 };
 
 int gro_cells_receive(struct gro_cells *gcells, struct sk_buff *skb)
 {
 	struct net_device *dev = skb->dev;
+	bool have_bh_lock = false;
 	struct gro_cell *cell;
 	int res;
 
@@ -24,11 +27,13 @@ int gro_cells_receive(struct gro_cells *gcells, struct sk_buff *skb)
 		goto unlock;
 	}
 
+	local_lock_nested_bh(&gcells->cells->bh_lock);
+	have_bh_lock = true;
 	cell = this_cpu_ptr(gcells->cells);
 
-	if (skb_queue_len(&cell->napi_skbs) > netdev_max_backlog) {
+	if (skb_queue_len(&cell->napi_skbs) > READ_ONCE(net_hotdata.max_backlog)) {
 drop:
-		atomic_long_inc(&dev->rx_dropped);
+		dev_core_stats_rx_dropped_inc(dev);
 		kfree_skb(skb);
 		res = NET_RX_DROP;
 		goto unlock;
@@ -41,6 +46,8 @@ drop:
 	res = NET_RX_SUCCESS;
 
 unlock:
+	if (have_bh_lock)
+		local_unlock_nested_bh(&gcells->cells->bh_lock);
 	rcu_read_unlock();
 	return res;
 }
@@ -54,7 +61,9 @@ static int gro_cell_poll(struct napi_struct *napi, int budget)
 	int work_done = 0;
 
 	while (work_done < budget) {
+		__local_lock_nested_bh(&cell->bh_lock);
 		skb = __skb_dequeue(&cell->napi_skbs);
+		__local_unlock_nested_bh(&cell->bh_lock);
 		if (!skb)
 			break;
 		napi_gro_receive(napi, skb);
@@ -78,19 +87,34 @@ int gro_cells_init(struct gro_cells *gcells, struct net_device *dev)
 		struct gro_cell *cell = per_cpu_ptr(gcells->cells, i);
 
 		__skb_queue_head_init(&cell->napi_skbs);
+		local_lock_init(&cell->bh_lock);
 
 		set_bit(NAPI_STATE_NO_BUSY_POLL, &cell->napi.state);
 
-		netif_napi_add(dev, &cell->napi, gro_cell_poll,
-			       NAPI_POLL_WEIGHT);
+		netif_napi_add(dev, &cell->napi, gro_cell_poll);
 		napi_enable(&cell->napi);
 	}
 	return 0;
 }
 EXPORT_SYMBOL(gro_cells_init);
 
+struct percpu_free_defer {
+	struct rcu_head rcu;
+	void __percpu	*ptr;
+};
+
+static void percpu_free_defer_callback(struct rcu_head *head)
+{
+	struct percpu_free_defer *defer;
+
+	defer = container_of(head, struct percpu_free_defer, rcu);
+	free_percpu(defer->ptr);
+	kfree(defer);
+}
+
 void gro_cells_destroy(struct gro_cells *gcells)
 {
+	struct percpu_free_defer *defer;
 	int i;
 
 	if (!gcells->cells)
@@ -99,10 +123,26 @@ void gro_cells_destroy(struct gro_cells *gcells)
 		struct gro_cell *cell = per_cpu_ptr(gcells->cells, i);
 
 		napi_disable(&cell->napi);
-		netif_napi_del(&cell->napi);
+		__netif_napi_del(&cell->napi);
 		__skb_queue_purge(&cell->napi_skbs);
 	}
-	free_percpu(gcells->cells);
+	/* We need to observe an rcu grace period before freeing ->cells,
+	 * because netpoll could access dev->napi_list under rcu protection.
+	 * Try hard using call_rcu() instead of synchronize_rcu(),
+	 * because we might be called from cleanup_net(), and we
+	 * definitely do not want to block this critical task.
+	 */
+	defer = kmalloc(sizeof(*defer), GFP_KERNEL | __GFP_NOWARN);
+	if (likely(defer)) {
+		defer->ptr = gcells->cells;
+		call_rcu(&defer->rcu, percpu_free_defer_callback);
+	} else {
+		/* We do not hold RTNL at this point, synchronize_net()
+		 * would not be able to expedite this sync.
+		 */
+		synchronize_rcu_expedited();
+		free_percpu(gcells->cells);
+	}
 	gcells->cells = NULL;
 }
 EXPORT_SYMBOL(gro_cells_destroy);