1// SPDX-License-Identifier: GPL-2.0
  2#include <linux/skbuff.h>
  3#include <linux/slab.h>
  4#include <linux/netdevice.h>
  5#include <net/gro_cells.h>
  6#include <net/hotdata.h>
  7
  8struct gro_cell {
  9	struct sk_buff_head	napi_skbs;
 10	struct napi_struct	napi;
 11};
 12
 13int gro_cells_receive(struct gro_cells *gcells, struct sk_buff *skb)
 14{
 15	struct net_device *dev = skb->dev;
 16	struct gro_cell *cell;
 17	int res;
 18
 19	rcu_read_lock();
 20	if (unlikely(!(dev->flags & IFF_UP)))
 21		goto drop;
 22
 23	if (!gcells->cells || skb_cloned(skb) || netif_elide_gro(dev)) {
 24		res = netif_rx(skb);
 25		goto unlock;
 26	}
 27
 28	cell = this_cpu_ptr(gcells->cells);
 29
 30	if (skb_queue_len(&cell->napi_skbs) > READ_ONCE(net_hotdata.max_backlog)) {
 31drop:
 32		dev_core_stats_rx_dropped_inc(dev);
 33		kfree_skb(skb);
 34		res = NET_RX_DROP;
 35		goto unlock;
 36	}
 37
 38	__skb_queue_tail(&cell->napi_skbs, skb);
 39	if (skb_queue_len(&cell->napi_skbs) == 1)
 40		napi_schedule(&cell->napi);
 41
 42	res = NET_RX_SUCCESS;
 43
 44unlock:
 45	rcu_read_unlock();
 46	return res;
 47}
 48EXPORT_SYMBOL(gro_cells_receive);
 49
 50/* called under BH context */
 51static int gro_cell_poll(struct napi_struct *napi, int budget)
 52{
 53	struct gro_cell *cell = container_of(napi, struct gro_cell, napi);
 54	struct sk_buff *skb;
 55	int work_done = 0;
 56
 57	while (work_done < budget) {
 58		skb = __skb_dequeue(&cell->napi_skbs);
 59		if (!skb)
 60			break;
 61		napi_gro_receive(napi, skb);
 62		work_done++;
 63	}
 64
 65	if (work_done < budget)
 66		napi_complete_done(napi, work_done);
 67	return work_done;
 68}
 69
 70int gro_cells_init(struct gro_cells *gcells, struct net_device *dev)
 71{
 72	int i;
 73
 74	gcells->cells = alloc_percpu(struct gro_cell);
 75	if (!gcells->cells)
 76		return -ENOMEM;
 77
 78	for_each_possible_cpu(i) {
 79		struct gro_cell *cell = per_cpu_ptr(gcells->cells, i);
 80
 81		__skb_queue_head_init(&cell->napi_skbs);
 82
 83		set_bit(NAPI_STATE_NO_BUSY_POLL, &cell->napi.state);
 84
 85		netif_napi_add(dev, &cell->napi, gro_cell_poll);
 86		napi_enable(&cell->napi);
 87	}
 88	return 0;
 89}
 90EXPORT_SYMBOL(gro_cells_init);
 91
 92struct percpu_free_defer {
 93	struct rcu_head rcu;
 94	void __percpu	*ptr;
 95};
 96
 97static void percpu_free_defer_callback(struct rcu_head *head)
 98{
 99	struct percpu_free_defer *defer;
100
101	defer = container_of(head, struct percpu_free_defer, rcu);
102	free_percpu(defer->ptr);
103	kfree(defer);
104}
105
106void gro_cells_destroy(struct gro_cells *gcells)
107{
108	struct percpu_free_defer *defer;
109	int i;
110
111	if (!gcells->cells)
112		return;
113	for_each_possible_cpu(i) {
114		struct gro_cell *cell = per_cpu_ptr(gcells->cells, i);
115
116		napi_disable(&cell->napi);
117		__netif_napi_del(&cell->napi);
118		__skb_queue_purge(&cell->napi_skbs);
119	}
120	/* We need to observe an rcu grace period before freeing ->cells,
121	 * because netpoll could access dev->napi_list under rcu protection.
122	 * Try hard using call_rcu() instead of synchronize_rcu(),
123	 * because we might be called from cleanup_net(), and we
124	 * definitely do not want to block this critical task.
125	 */
126	defer = kmalloc(sizeof(*defer), GFP_KERNEL | __GFP_NOWARN);
127	if (likely(defer)) {
128		defer->ptr = gcells->cells;
129		call_rcu(&defer->rcu, percpu_free_defer_callback);
130	} else {
131		/* We do not hold RTNL at this point, synchronize_net()
132		 * would not be able to expedite this sync.
133		 */
134		synchronize_rcu_expedited();
135		free_percpu(gcells->cells);
136	}
137	gcells->cells = NULL;
138}
139EXPORT_SYMBOL(gro_cells_destroy);