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/types.h> 14 #include <linux/kernel.h> 15 #include <linux/errno.h> 16 #include <linux/skbuff.h> 17 #include <net/pkt_sched.h> 18 19 /* 1 band FIFO pseudo-"scheduler" */ 20 21 struct fifo_sched_data 22 { 23 u32 limit; 24 }; 25 26 static int bfifo_enqueue(struct sk_buff *skb, struct Qdisc* sch) 27 { 28 struct fifo_sched_data *q = qdisc_priv(sch); 29 30 if (likely(sch->qstats.backlog + qdisc_pkt_len(skb) <= q->limit)) 31 return qdisc_enqueue_tail(skb, sch); 32 33 return qdisc_reshape_fail(skb, sch); 34 } 35 36 static int pfifo_enqueue(struct sk_buff *skb, struct Qdisc* sch) 37 { 38 struct fifo_sched_data *q = qdisc_priv(sch); 39 40 if (likely(skb_queue_len(&sch->q) < q->limit)) 41 return qdisc_enqueue_tail(skb, sch); 42 43 return qdisc_reshape_fail(skb, sch); 44 } 45 46 static int fifo_init(struct Qdisc *sch, struct nlattr *opt) 47 { 48 struct fifo_sched_data *q = qdisc_priv(sch); 49 50 if (opt == NULL) { 51 u32 limit = qdisc_dev(sch)->tx_queue_len ? : 1; 52 53 if (sch->ops == &bfifo_qdisc_ops) 54 limit *= psched_mtu(qdisc_dev(sch)); 55 56 q->limit = limit; 57 } else { 58 struct tc_fifo_qopt *ctl = nla_data(opt); 59 60 if (nla_len(opt) < sizeof(*ctl)) 61 return -EINVAL; 62 63 q->limit = ctl->limit; 64 } 65 66 return 0; 67 } 68 69 static int fifo_dump(struct Qdisc *sch, struct sk_buff *skb) 70 { 71 struct fifo_sched_data *q = qdisc_priv(sch); 72 struct tc_fifo_qopt opt = { .limit = q->limit }; 73 74 NLA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt); 75 return skb->len; 76 77 nla_put_failure: 78 return -1; 79 } 80 81 struct Qdisc_ops pfifo_qdisc_ops __read_mostly = { 82 .id = "pfifo", 83 .priv_size = sizeof(struct fifo_sched_data), 84 .enqueue = pfifo_enqueue, 85 .dequeue = qdisc_dequeue_head, 86 .peek = qdisc_peek_head, 87 .drop = qdisc_queue_drop, 88 .init = fifo_init, 89 .reset = qdisc_reset_queue, 90 .change = fifo_init, 91 .dump = fifo_dump, 92 .owner = THIS_MODULE, 93 }; 94 EXPORT_SYMBOL(pfifo_qdisc_ops); 95 96 struct Qdisc_ops bfifo_qdisc_ops __read_mostly = { 97 .id = "bfifo", 98 .priv_size = sizeof(struct fifo_sched_data), 99 .enqueue = bfifo_enqueue, 100 .dequeue = qdisc_dequeue_head, 101 .peek = qdisc_peek_head, 102 .drop = qdisc_queue_drop, 103 .init = fifo_init, 104 .reset = qdisc_reset_queue, 105 .change = fifo_init, 106 .dump = fifo_dump, 107 .owner = THIS_MODULE, 108 }; 109 EXPORT_SYMBOL(bfifo_qdisc_ops); 110 111 /* Pass size change message down to embedded FIFO */ 112 int fifo_set_limit(struct Qdisc *q, unsigned int limit) 113 { 114 struct nlattr *nla; 115 int ret = -ENOMEM; 116 117 /* Hack to avoid sending change message to non-FIFO */ 118 if (strncmp(q->ops->id + 1, "fifo", 4) != 0) 119 return 0; 120 121 nla = kmalloc(nla_attr_size(sizeof(struct tc_fifo_qopt)), GFP_KERNEL); 122 if (nla) { 123 nla->nla_type = RTM_NEWQDISC; 124 nla->nla_len = nla_attr_size(sizeof(struct tc_fifo_qopt)); 125 ((struct tc_fifo_qopt *)nla_data(nla))->limit = limit; 126 127 ret = q->ops->change(q, nla); 128 kfree(nla); 129 } 130 return ret; 131 } 132 EXPORT_SYMBOL(fifo_set_limit); 133 134 struct Qdisc *fifo_create_dflt(struct Qdisc *sch, struct Qdisc_ops *ops, 135 unsigned int limit) 136 { 137 struct Qdisc *q; 138 int err = -ENOMEM; 139 140 q = qdisc_create_dflt(qdisc_dev(sch), sch->dev_queue, 141 ops, TC_H_MAKE(sch->handle, 1)); 142 if (q) { 143 err = fifo_set_limit(q, limit); 144 if (err < 0) { 145 qdisc_destroy(q); 146 q = NULL; 147 } 148 } 149 150 return q ? : ERR_PTR(err); 151 } 152 EXPORT_SYMBOL(fifo_create_dflt); 153