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(list_: &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(list: &cell->napi_skbs, newsk: skb);
39 if (skb_queue_len(list_: &cell->napi_skbs) == 1)
40 napi_schedule(n: &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(list: &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(n: 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(list: &cell->napi_skbs);
82
83 set_bit(nr: NAPI_STATE_NO_BUSY_POLL, addr: &cell->napi.state);
84
85 netif_napi_add(dev, napi: &cell->napi, poll: gro_cell_poll);
86 napi_enable(n: &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(pdata: defer->ptr);
103 kfree(objp: 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(n: &cell->napi);
117 __netif_napi_del(napi: &cell->napi);
118 __skb_queue_purge(list: &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(head: &defer->rcu, func: 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(pdata: gcells->cells);
136 }
137 gcells->cells = NULL;
138}
139EXPORT_SYMBOL(gro_cells_destroy);
140