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