projects/linux·blob master · refs

150 lines · 3.5 KiB

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