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
8 struct gro_cell {
9 struct sk_buff_head napi_skbs;
10 struct napi_struct napi;
11 };
12
13 int 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)) {
31 drop:
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
44 unlock:
45 rcu_read_unlock();
46 return res;
47 }
48 EXPORT_SYMBOL(gro_cells_receive);
49
50 /* called under BH context */
51 static 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
70 int 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 }
90 EXPORT_SYMBOL(gro_cells_init);
91
92 struct percpu_free_defer {
93 struct rcu_head rcu;
94 void __percpu *ptr;
95 };
96
97 static 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
106 void 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 }
139 EXPORT_SYMBOL(gro_cells_destroy);
140
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