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);
140