1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* |
3 | * net/sched/sch_fifo.c The simplest FIFO queue. |
4 | * |
5 | * Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru> |
6 | */ |
7 | |
8 | #include <linux/module.h> |
9 | #include <linux/slab.h> |
10 | #include <linux/types.h> |
11 | #include <linux/kernel.h> |
12 | #include <linux/errno.h> |
13 | #include <linux/skbuff.h> |
14 | #include <net/pkt_sched.h> |
15 | #include <net/pkt_cls.h> |
16 | |
17 | /* 1 band FIFO pseudo-"scheduler" */ |
18 | |
19 | static int bfifo_enqueue(struct sk_buff *skb, struct Qdisc *sch, |
20 | struct sk_buff **to_free) |
21 | { |
22 | if (likely(sch->qstats.backlog + qdisc_pkt_len(skb) <= sch->limit)) |
23 | return qdisc_enqueue_tail(skb, sch); |
24 | |
25 | return qdisc_drop(skb, sch, to_free); |
26 | } |
27 | |
28 | static int pfifo_enqueue(struct sk_buff *skb, struct Qdisc *sch, |
29 | struct sk_buff **to_free) |
30 | { |
31 | if (likely(sch->q.qlen < sch->limit)) |
32 | return qdisc_enqueue_tail(skb, sch); |
33 | |
34 | return qdisc_drop(skb, sch, to_free); |
35 | } |
36 | |
37 | static int pfifo_tail_enqueue(struct sk_buff *skb, struct Qdisc *sch, |
38 | struct sk_buff **to_free) |
39 | { |
40 | unsigned int prev_backlog; |
41 | |
42 | if (likely(sch->q.qlen < sch->limit)) |
43 | return qdisc_enqueue_tail(skb, sch); |
44 | |
45 | prev_backlog = sch->qstats.backlog; |
46 | /* queue full, remove one skb to fulfill the limit */ |
47 | __qdisc_queue_drop_head(sch, qh: &sch->q, to_free); |
48 | qdisc_qstats_drop(sch); |
49 | qdisc_enqueue_tail(skb, sch); |
50 | |
51 | qdisc_tree_reduce_backlog(qdisc: sch, n: 0, len: prev_backlog - sch->qstats.backlog); |
52 | return NET_XMIT_CN; |
53 | } |
54 | |
55 | static void fifo_offload_init(struct Qdisc *sch) |
56 | { |
57 | struct net_device *dev = qdisc_dev(qdisc: sch); |
58 | struct tc_fifo_qopt_offload qopt; |
59 | |
60 | if (!tc_can_offload(dev) || !dev->netdev_ops->ndo_setup_tc) |
61 | return; |
62 | |
63 | qopt.command = TC_FIFO_REPLACE; |
64 | qopt.handle = sch->handle; |
65 | qopt.parent = sch->parent; |
66 | dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_QDISC_FIFO, &qopt); |
67 | } |
68 | |
69 | static void fifo_offload_destroy(struct Qdisc *sch) |
70 | { |
71 | struct net_device *dev = qdisc_dev(qdisc: sch); |
72 | struct tc_fifo_qopt_offload qopt; |
73 | |
74 | if (!tc_can_offload(dev) || !dev->netdev_ops->ndo_setup_tc) |
75 | return; |
76 | |
77 | qopt.command = TC_FIFO_DESTROY; |
78 | qopt.handle = sch->handle; |
79 | qopt.parent = sch->parent; |
80 | dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_QDISC_FIFO, &qopt); |
81 | } |
82 | |
83 | static int fifo_offload_dump(struct Qdisc *sch) |
84 | { |
85 | struct tc_fifo_qopt_offload qopt; |
86 | |
87 | qopt.command = TC_FIFO_STATS; |
88 | qopt.handle = sch->handle; |
89 | qopt.parent = sch->parent; |
90 | qopt.stats.bstats = &sch->bstats; |
91 | qopt.stats.qstats = &sch->qstats; |
92 | |
93 | return qdisc_offload_dump_helper(q: sch, type: TC_SETUP_QDISC_FIFO, type_data: &qopt); |
94 | } |
95 | |
96 | static int __fifo_init(struct Qdisc *sch, struct nlattr *opt, |
97 | struct netlink_ext_ack *extack) |
98 | { |
99 | bool bypass; |
100 | bool is_bfifo = sch->ops == &bfifo_qdisc_ops; |
101 | |
102 | if (opt == NULL) { |
103 | u32 limit = qdisc_dev(qdisc: sch)->tx_queue_len; |
104 | |
105 | if (is_bfifo) |
106 | limit *= psched_mtu(dev: qdisc_dev(qdisc: sch)); |
107 | |
108 | sch->limit = limit; |
109 | } else { |
110 | struct tc_fifo_qopt *ctl = nla_data(nla: opt); |
111 | |
112 | if (nla_len(nla: opt) < sizeof(*ctl)) |
113 | return -EINVAL; |
114 | |
115 | sch->limit = ctl->limit; |
116 | } |
117 | |
118 | if (is_bfifo) |
119 | bypass = sch->limit >= psched_mtu(dev: qdisc_dev(qdisc: sch)); |
120 | else |
121 | bypass = sch->limit >= 1; |
122 | |
123 | if (bypass) |
124 | sch->flags |= TCQ_F_CAN_BYPASS; |
125 | else |
126 | sch->flags &= ~TCQ_F_CAN_BYPASS; |
127 | |
128 | return 0; |
129 | } |
130 | |
131 | static int fifo_init(struct Qdisc *sch, struct nlattr *opt, |
132 | struct netlink_ext_ack *extack) |
133 | { |
134 | int err; |
135 | |
136 | err = __fifo_init(sch, opt, extack); |
137 | if (err) |
138 | return err; |
139 | |
140 | fifo_offload_init(sch); |
141 | return 0; |
142 | } |
143 | |
144 | static int fifo_hd_init(struct Qdisc *sch, struct nlattr *opt, |
145 | struct netlink_ext_ack *extack) |
146 | { |
147 | return __fifo_init(sch, opt, extack); |
148 | } |
149 | |
150 | static void fifo_destroy(struct Qdisc *sch) |
151 | { |
152 | fifo_offload_destroy(sch); |
153 | } |
154 | |
155 | static int __fifo_dump(struct Qdisc *sch, struct sk_buff *skb) |
156 | { |
157 | struct tc_fifo_qopt opt = { .limit = sch->limit }; |
158 | |
159 | if (nla_put(skb, attrtype: TCA_OPTIONS, attrlen: sizeof(opt), data: &opt)) |
160 | goto nla_put_failure; |
161 | return skb->len; |
162 | |
163 | nla_put_failure: |
164 | return -1; |
165 | } |
166 | |
167 | static int fifo_dump(struct Qdisc *sch, struct sk_buff *skb) |
168 | { |
169 | int err; |
170 | |
171 | err = fifo_offload_dump(sch); |
172 | if (err) |
173 | return err; |
174 | |
175 | return __fifo_dump(sch, skb); |
176 | } |
177 | |
178 | static int fifo_hd_dump(struct Qdisc *sch, struct sk_buff *skb) |
179 | { |
180 | return __fifo_dump(sch, skb); |
181 | } |
182 | |
183 | struct Qdisc_ops pfifo_qdisc_ops __read_mostly = { |
184 | .id = "pfifo" , |
185 | .priv_size = 0, |
186 | .enqueue = pfifo_enqueue, |
187 | .dequeue = qdisc_dequeue_head, |
188 | .peek = qdisc_peek_head, |
189 | .init = fifo_init, |
190 | .destroy = fifo_destroy, |
191 | .reset = qdisc_reset_queue, |
192 | .change = fifo_init, |
193 | .dump = fifo_dump, |
194 | .owner = THIS_MODULE, |
195 | }; |
196 | EXPORT_SYMBOL(pfifo_qdisc_ops); |
197 | |
198 | struct Qdisc_ops bfifo_qdisc_ops __read_mostly = { |
199 | .id = "bfifo" , |
200 | .priv_size = 0, |
201 | .enqueue = bfifo_enqueue, |
202 | .dequeue = qdisc_dequeue_head, |
203 | .peek = qdisc_peek_head, |
204 | .init = fifo_init, |
205 | .destroy = fifo_destroy, |
206 | .reset = qdisc_reset_queue, |
207 | .change = fifo_init, |
208 | .dump = fifo_dump, |
209 | .owner = THIS_MODULE, |
210 | }; |
211 | EXPORT_SYMBOL(bfifo_qdisc_ops); |
212 | |
213 | struct Qdisc_ops pfifo_head_drop_qdisc_ops __read_mostly = { |
214 | .id = "pfifo_head_drop" , |
215 | .priv_size = 0, |
216 | .enqueue = pfifo_tail_enqueue, |
217 | .dequeue = qdisc_dequeue_head, |
218 | .peek = qdisc_peek_head, |
219 | .init = fifo_hd_init, |
220 | .reset = qdisc_reset_queue, |
221 | .change = fifo_hd_init, |
222 | .dump = fifo_hd_dump, |
223 | .owner = THIS_MODULE, |
224 | }; |
225 | |
226 | /* Pass size change message down to embedded FIFO */ |
227 | int fifo_set_limit(struct Qdisc *q, unsigned int limit) |
228 | { |
229 | struct nlattr *nla; |
230 | int ret = -ENOMEM; |
231 | |
232 | /* Hack to avoid sending change message to non-FIFO */ |
233 | if (strncmp(q->ops->id + 1, "fifo" , 4) != 0) |
234 | return 0; |
235 | |
236 | if (!q->ops->change) |
237 | return 0; |
238 | |
239 | nla = kmalloc(size: nla_attr_size(payload: sizeof(struct tc_fifo_qopt)), GFP_KERNEL); |
240 | if (nla) { |
241 | nla->nla_type = RTM_NEWQDISC; |
242 | nla->nla_len = nla_attr_size(payload: sizeof(struct tc_fifo_qopt)); |
243 | ((struct tc_fifo_qopt *)nla_data(nla))->limit = limit; |
244 | |
245 | ret = q->ops->change(q, nla, NULL); |
246 | kfree(objp: nla); |
247 | } |
248 | return ret; |
249 | } |
250 | EXPORT_SYMBOL(fifo_set_limit); |
251 | |
252 | struct Qdisc *fifo_create_dflt(struct Qdisc *sch, struct Qdisc_ops *ops, |
253 | unsigned int limit, |
254 | struct netlink_ext_ack *extack) |
255 | { |
256 | struct Qdisc *q; |
257 | int err = -ENOMEM; |
258 | |
259 | q = qdisc_create_dflt(dev_queue: sch->dev_queue, ops, TC_H_MAKE(sch->handle, 1), |
260 | extack); |
261 | if (q) { |
262 | err = fifo_set_limit(q, limit); |
263 | if (err < 0) { |
264 | qdisc_put(qdisc: q); |
265 | q = NULL; |
266 | } |
267 | } |
268 | |
269 | return q ? : ERR_PTR(error: err); |
270 | } |
271 | EXPORT_SYMBOL(fifo_create_dflt); |
272 | |