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 local_lock_t bh_lock;
12 };
13
gro_cells_receive(struct gro_cells * gcells,struct sk_buff * skb)14 int gro_cells_receive(struct gro_cells *gcells, struct sk_buff *skb)
15 {
16 struct net_device *dev = skb->dev;
17 bool have_bh_lock = false;
18 struct gro_cell *cell;
19 int res;
20
21 rcu_read_lock();
22 if (unlikely(!(dev->flags & IFF_UP)))
23 goto drop;
24
25 if (!gcells->cells || skb_cloned(skb) || netif_elide_gro(dev)) {
26 res = netif_rx(skb);
27 goto unlock;
28 }
29
30 local_lock_nested_bh(&gcells->cells->bh_lock);
31 have_bh_lock = true;
32 cell = this_cpu_ptr(gcells->cells);
33
34 if (skb_queue_len(&cell->napi_skbs) > READ_ONCE(net_hotdata.max_backlog)) {
35 drop:
36 dev_core_stats_rx_dropped_inc(dev);
37 kfree_skb(skb);
38 res = NET_RX_DROP;
39 goto unlock;
40 }
41
42 __skb_queue_tail(&cell->napi_skbs, skb);
43 if (skb_queue_len(&cell->napi_skbs) == 1)
44 napi_schedule(&cell->napi);
45
46 if (have_bh_lock)
47 local_unlock_nested_bh(&gcells->cells->bh_lock);
48
49 res = NET_RX_SUCCESS;
50
51 unlock:
52 rcu_read_unlock();
53 return res;
54 }
55 EXPORT_SYMBOL(gro_cells_receive);
56
57 /* called under BH context */
gro_cell_poll(struct napi_struct * napi,int budget)58 static int gro_cell_poll(struct napi_struct *napi, int budget)
59 {
60 struct gro_cell *cell = container_of(napi, struct gro_cell, napi);
61 struct sk_buff *skb;
62 int work_done = 0;
63
64 __local_lock_nested_bh(&cell->bh_lock);
65 while (work_done < budget) {
66 skb = __skb_dequeue(&cell->napi_skbs);
67 if (!skb)
68 break;
69 napi_gro_receive(napi, skb);
70 work_done++;
71 }
72
73 if (work_done < budget)
74 napi_complete_done(napi, work_done);
75 __local_unlock_nested_bh(&cell->bh_lock);
76 return work_done;
77 }
78
gro_cells_init(struct gro_cells * gcells,struct net_device * dev)79 int gro_cells_init(struct gro_cells *gcells, struct net_device *dev)
80 {
81 int i;
82
83 gcells->cells = alloc_percpu(struct gro_cell);
84 if (!gcells->cells)
85 return -ENOMEM;
86
87 for_each_possible_cpu(i) {
88 struct gro_cell *cell = per_cpu_ptr(gcells->cells, i);
89
90 __skb_queue_head_init(&cell->napi_skbs);
91 local_lock_init(&cell->bh_lock);
92
93 set_bit(NAPI_STATE_NO_BUSY_POLL, &cell->napi.state);
94
95 netif_napi_add(dev, &cell->napi, gro_cell_poll);
96 napi_enable(&cell->napi);
97 }
98 return 0;
99 }
100 EXPORT_SYMBOL(gro_cells_init);
101
102 struct percpu_free_defer {
103 struct rcu_head rcu;
104 void __percpu *ptr;
105 };
106
percpu_free_defer_callback(struct rcu_head * head)107 static void percpu_free_defer_callback(struct rcu_head *head)
108 {
109 struct percpu_free_defer *defer;
110
111 defer = container_of(head, struct percpu_free_defer, rcu);
112 free_percpu(defer->ptr);
113 kfree(defer);
114 }
115
gro_cells_destroy(struct gro_cells * gcells)116 void gro_cells_destroy(struct gro_cells *gcells)
117 {
118 struct percpu_free_defer *defer;
119 int i;
120
121 if (!gcells->cells)
122 return;
123 for_each_possible_cpu(i) {
124 struct gro_cell *cell = per_cpu_ptr(gcells->cells, i);
125
126 napi_disable(&cell->napi);
127 __netif_napi_del(&cell->napi);
128 __skb_queue_purge(&cell->napi_skbs);
129 }
130 /* We need to observe an rcu grace period before freeing ->cells,
131 * because netpoll could access dev->napi_list under rcu protection.
132 * Try hard using call_rcu() instead of synchronize_rcu(),
133 * because we might be called from cleanup_net(), and we
134 * definitely do not want to block this critical task.
135 */
136 defer = kmalloc(sizeof(*defer), GFP_KERNEL | __GFP_NOWARN);
137 if (likely(defer)) {
138 defer->ptr = gcells->cells;
139 call_rcu(&defer->rcu, percpu_free_defer_callback);
140 } else {
141 /* We do not hold RTNL at this point, synchronize_net()
142 * would not be able to expedite this sync.
143 */
144 synchronize_rcu_expedited();
145 free_percpu(gcells->cells);
146 }
147 gcells->cells = NULL;
148 }
149 EXPORT_SYMBOL(gro_cells_destroy);
150