| 1 | /* |
| 2 | * net/sched/sch_fifo.c The simplest FIFO queue. |
| 3 | * |
| 4 | * This program is free software; you can redistribute it and/or |
| 5 | * modify it under the terms of the GNU General Public License |
| 6 | * as published by the Free Software Foundation; either version |
| 7 | * 2 of the License, or (at your option) any later version. |
| 8 | * |
| 9 | * Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru> |
| 10 | */ |
| 11 | |
| 12 | #include <linux/module.h> |
| 13 | #include <linux/slab.h> |
| 14 | #include <linux/types.h> |
| 15 | #include <linux/kernel.h> |
| 16 | #include <linux/errno.h> |
| 17 | #include <linux/skbuff.h> |
| 18 | #include <net/pkt_sched.h> |
| 19 | |
| 20 | /* 1 band FIFO pseudo-"scheduler" */ |
| 21 | |
| 22 | static int bfifo_enqueue(struct sk_buff *skb, struct Qdisc *sch, |
| 23 | struct sk_buff **to_free) |
| 24 | { |
| 25 | if (likely(sch->qstats.backlog + qdisc_pkt_len(skb) <= sch->limit)) |
| 26 | return qdisc_enqueue_tail(skb, sch); |
| 27 | |
| 28 | return qdisc_drop(skb, sch, to_free); |
| 29 | } |
| 30 | |
| 31 | static int pfifo_enqueue(struct sk_buff *skb, struct Qdisc *sch, |
| 32 | struct sk_buff **to_free) |
| 33 | { |
| 34 | if (likely(skb_queue_len(&sch->q) < sch->limit)) |
| 35 | return qdisc_enqueue_tail(skb, sch); |
| 36 | |
| 37 | return qdisc_drop(skb, sch, to_free); |
| 38 | } |
| 39 | |
| 40 | static int pfifo_tail_enqueue(struct sk_buff *skb, struct Qdisc *sch, |
| 41 | struct sk_buff **to_free) |
| 42 | { |
| 43 | unsigned int prev_backlog; |
| 44 | |
| 45 | if (likely(skb_queue_len(&sch->q) < sch->limit)) |
| 46 | return qdisc_enqueue_tail(skb, sch); |
| 47 | |
| 48 | prev_backlog = sch->qstats.backlog; |
| 49 | /* queue full, remove one skb to fulfill the limit */ |
| 50 | __qdisc_queue_drop_head(sch, &sch->q, to_free); |
| 51 | qdisc_qstats_drop(sch); |
| 52 | qdisc_enqueue_tail(skb, sch); |
| 53 | |
| 54 | qdisc_tree_reduce_backlog(sch, 0, prev_backlog - sch->qstats.backlog); |
| 55 | return NET_XMIT_CN; |
| 56 | } |
| 57 | |
| 58 | static int fifo_init(struct Qdisc *sch, struct nlattr *opt) |
| 59 | { |
| 60 | bool bypass; |
| 61 | bool is_bfifo = sch->ops == &bfifo_qdisc_ops; |
| 62 | |
| 63 | if (opt == NULL) { |
| 64 | u32 limit = qdisc_dev(sch)->tx_queue_len; |
| 65 | |
| 66 | if (is_bfifo) |
| 67 | limit *= psched_mtu(qdisc_dev(sch)); |
| 68 | |
| 69 | sch->limit = limit; |
| 70 | } else { |
| 71 | struct tc_fifo_qopt *ctl = nla_data(opt); |
| 72 | |
| 73 | if (nla_len(opt) < sizeof(*ctl)) |
| 74 | return -EINVAL; |
| 75 | |
| 76 | sch->limit = ctl->limit; |
| 77 | } |
| 78 | |
| 79 | if (is_bfifo) |
| 80 | bypass = sch->limit >= psched_mtu(qdisc_dev(sch)); |
| 81 | else |
| 82 | bypass = sch->limit >= 1; |
| 83 | |
| 84 | if (bypass) |
| 85 | sch->flags |= TCQ_F_CAN_BYPASS; |
| 86 | else |
| 87 | sch->flags &= ~TCQ_F_CAN_BYPASS; |
| 88 | return 0; |
| 89 | } |
| 90 | |
| 91 | static int fifo_dump(struct Qdisc *sch, struct sk_buff *skb) |
| 92 | { |
| 93 | struct tc_fifo_qopt opt = { .limit = sch->limit }; |
| 94 | |
| 95 | if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt)) |
| 96 | goto nla_put_failure; |
| 97 | return skb->len; |
| 98 | |
| 99 | nla_put_failure: |
| 100 | return -1; |
| 101 | } |
| 102 | |
| 103 | struct Qdisc_ops pfifo_qdisc_ops __read_mostly = { |
| 104 | .id = "pfifo", |
| 105 | .priv_size = 0, |
| 106 | .enqueue = pfifo_enqueue, |
| 107 | .dequeue = qdisc_dequeue_head, |
| 108 | .peek = qdisc_peek_head, |
| 109 | .init = fifo_init, |
| 110 | .reset = qdisc_reset_queue, |
| 111 | .change = fifo_init, |
| 112 | .dump = fifo_dump, |
| 113 | .owner = THIS_MODULE, |
| 114 | }; |
| 115 | EXPORT_SYMBOL(pfifo_qdisc_ops); |
| 116 | |
| 117 | struct Qdisc_ops bfifo_qdisc_ops __read_mostly = { |
| 118 | .id = "bfifo", |
| 119 | .priv_size = 0, |
| 120 | .enqueue = bfifo_enqueue, |
| 121 | .dequeue = qdisc_dequeue_head, |
| 122 | .peek = qdisc_peek_head, |
| 123 | .init = fifo_init, |
| 124 | .reset = qdisc_reset_queue, |
| 125 | .change = fifo_init, |
| 126 | .dump = fifo_dump, |
| 127 | .owner = THIS_MODULE, |
| 128 | }; |
| 129 | EXPORT_SYMBOL(bfifo_qdisc_ops); |
| 130 | |
| 131 | struct Qdisc_ops pfifo_head_drop_qdisc_ops __read_mostly = { |
| 132 | .id = "pfifo_head_drop", |
| 133 | .priv_size = 0, |
| 134 | .enqueue = pfifo_tail_enqueue, |
| 135 | .dequeue = qdisc_dequeue_head, |
| 136 | .peek = qdisc_peek_head, |
| 137 | .init = fifo_init, |
| 138 | .reset = qdisc_reset_queue, |
| 139 | .change = fifo_init, |
| 140 | .dump = fifo_dump, |
| 141 | .owner = THIS_MODULE, |
| 142 | }; |
| 143 | |
| 144 | /* Pass size change message down to embedded FIFO */ |
| 145 | int fifo_set_limit(struct Qdisc *q, unsigned int limit) |
| 146 | { |
| 147 | struct nlattr *nla; |
| 148 | int ret = -ENOMEM; |
| 149 | |
| 150 | /* Hack to avoid sending change message to non-FIFO */ |
| 151 | if (strncmp(q->ops->id + 1, "fifo", 4) != 0) |
| 152 | return 0; |
| 153 | |
| 154 | nla = kmalloc(nla_attr_size(sizeof(struct tc_fifo_qopt)), GFP_KERNEL); |
| 155 | if (nla) { |
| 156 | nla->nla_type = RTM_NEWQDISC; |
| 157 | nla->nla_len = nla_attr_size(sizeof(struct tc_fifo_qopt)); |
| 158 | ((struct tc_fifo_qopt *)nla_data(nla))->limit = limit; |
| 159 | |
| 160 | ret = q->ops->change(q, nla); |
| 161 | kfree(nla); |
| 162 | } |
| 163 | return ret; |
| 164 | } |
| 165 | EXPORT_SYMBOL(fifo_set_limit); |
| 166 | |
| 167 | struct Qdisc *fifo_create_dflt(struct Qdisc *sch, struct Qdisc_ops *ops, |
| 168 | unsigned int limit) |
| 169 | { |
| 170 | struct Qdisc *q; |
| 171 | int err = -ENOMEM; |
| 172 | |
| 173 | q = qdisc_create_dflt(sch->dev_queue, ops, TC_H_MAKE(sch->handle, 1)); |
| 174 | if (q) { |
| 175 | err = fifo_set_limit(q, limit); |
| 176 | if (err < 0) { |
| 177 | qdisc_destroy(q); |
| 178 | q = NULL; |
| 179 | } |
| 180 | } |
| 181 | |
| 182 | return q ? : ERR_PTR(err); |
| 183 | } |
| 184 | EXPORT_SYMBOL(fifo_create_dflt); |