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/config.h> 13 #include <linux/module.h> 14 #include <linux/types.h> 15 #include <linux/kernel.h> 16 #include <linux/errno.h> 17 #include <linux/netdevice.h> 18 #include <linux/skbuff.h> 19 #include <net/pkt_sched.h> 20 21 /* 1 band FIFO pseudo-"scheduler" */ 22 23 struct fifo_sched_data 24 { 25 u32 limit; 26 }; 27 28 static int bfifo_enqueue(struct sk_buff *skb, struct Qdisc* sch) 29 { 30 struct fifo_sched_data *q = qdisc_priv(sch); 31 32 if (likely(sch->qstats.backlog + skb->len <= q->limit)) 33 return qdisc_enqueue_tail(skb, sch); 34 35 return qdisc_reshape_fail(skb, sch); 36 } 37 38 static int pfifo_enqueue(struct sk_buff *skb, struct Qdisc* sch) 39 { 40 struct fifo_sched_data *q = qdisc_priv(sch); 41 42 if (likely(skb_queue_len(&sch->q) < q->limit)) 43 return qdisc_enqueue_tail(skb, sch); 44 45 return qdisc_reshape_fail(skb, sch); 46 } 47 48 static int fifo_init(struct Qdisc *sch, struct rtattr *opt) 49 { 50 struct fifo_sched_data *q = qdisc_priv(sch); 51 52 if (opt == NULL) { 53 u32 limit = sch->dev->tx_queue_len ? : 1; 54 55 if (sch->ops == &bfifo_qdisc_ops) 56 limit *= sch->dev->mtu; 57 58 q->limit = limit; 59 } else { 60 struct tc_fifo_qopt *ctl = RTA_DATA(opt); 61 62 if (RTA_PAYLOAD(opt) < sizeof(*ctl)) 63 return -EINVAL; 64 65 q->limit = ctl->limit; 66 } 67 68 return 0; 69 } 70 71 static int fifo_dump(struct Qdisc *sch, struct sk_buff *skb) 72 { 73 struct fifo_sched_data *q = qdisc_priv(sch); 74 struct tc_fifo_qopt opt = { .limit = q->limit }; 75 76 RTA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt); 77 return skb->len; 78 79 rtattr_failure: 80 return -1; 81 } 82 83 struct Qdisc_ops pfifo_qdisc_ops = { 84 .id = "pfifo", 85 .priv_size = sizeof(struct fifo_sched_data), 86 .enqueue = pfifo_enqueue, 87 .dequeue = qdisc_dequeue_head, 88 .requeue = qdisc_requeue, 89 .drop = qdisc_queue_drop, 90 .init = fifo_init, 91 .reset = qdisc_reset_queue, 92 .change = fifo_init, 93 .dump = fifo_dump, 94 .owner = THIS_MODULE, 95 }; 96 97 struct Qdisc_ops bfifo_qdisc_ops = { 98 .id = "bfifo", 99 .priv_size = sizeof(struct fifo_sched_data), 100 .enqueue = bfifo_enqueue, 101 .dequeue = qdisc_dequeue_head, 102 .requeue = qdisc_requeue, 103 .drop = qdisc_queue_drop, 104 .init = fifo_init, 105 .reset = qdisc_reset_queue, 106 .change = fifo_init, 107 .dump = fifo_dump, 108 .owner = THIS_MODULE, 109 }; 110 111 EXPORT_SYMBOL(bfifo_qdisc_ops); 112 EXPORT_SYMBOL(pfifo_qdisc_ops); 113