xref: /kernel/linux/linux-6.6/net/core/gro_cells.c (revision 62306a36) 
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);
139