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 | |
7 | struct gro_cell { |
8 | struct sk_buff_head napi_skbs; |
9 | struct napi_struct napi; |
10 | }; |
11 | |
12 | int 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(list_: &cell->napi_skbs) > READ_ONCE(netdev_max_backlog)) { |
30 | drop: |
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(list: &cell->napi_skbs, newsk: skb); |
38 | if (skb_queue_len(list_: &cell->napi_skbs) == 1) |
39 | napi_schedule(n: &cell->napi); |
40 | |
41 | res = NET_RX_SUCCESS; |
42 | |
43 | unlock: |
44 | rcu_read_unlock(); |
45 | return res; |
46 | } |
47 | EXPORT_SYMBOL(gro_cells_receive); |
48 | |
49 | /* called under BH context */ |
50 | static 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(list: &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(n: napi, work_done); |
66 | return work_done; |
67 | } |
68 | |
69 | int 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(list: &cell->napi_skbs); |
81 | |
82 | set_bit(nr: NAPI_STATE_NO_BUSY_POLL, addr: &cell->napi.state); |
83 | |
84 | netif_napi_add(dev, napi: &cell->napi, poll: gro_cell_poll); |
85 | napi_enable(n: &cell->napi); |
86 | } |
87 | return 0; |
88 | } |
89 | EXPORT_SYMBOL(gro_cells_init); |
90 | |
91 | struct percpu_free_defer { |
92 | struct rcu_head rcu; |
93 | void __percpu *ptr; |
94 | }; |
95 | |
96 | static 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(pdata: defer->ptr); |
102 | kfree(objp: defer); |
103 | } |
104 | |
105 | void 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(n: &cell->napi); |
116 | __netif_napi_del(napi: &cell->napi); |
117 | __skb_queue_purge(list: &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(size: sizeof(*defer), GFP_KERNEL | __GFP_NOWARN); |
126 | if (likely(defer)) { |
127 | defer->ptr = gcells->cells; |
128 | call_rcu(head: &defer->rcu, func: 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(pdata: gcells->cells); |
135 | } |
136 | gcells->cells = NULL; |
137 | } |
138 | EXPORT_SYMBOL(gro_cells_destroy); |
139 | |