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