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