| Tomasz Grobelny | 871a2c1 | 2010-12-04 13:38:01 +0100 | [diff] [blame^] | 1 | /* |
| 2 | * net/dccp/qpolicy.c |
| 3 | * |
| 4 | * Policy-based packet dequeueing interface for DCCP. |
| 5 | * |
| 6 | * Copyright (c) 2008 Tomasz Grobelny <tomasz@grobelny.oswiecenia.net> |
| 7 | * |
| 8 | * This program is free software; you can redistribute it and/or |
| 9 | * modify it under the terms of the GNU General Public License v2 |
| 10 | * as published by the Free Software Foundation. |
| 11 | */ |
| 12 | #include "dccp.h" |
| 13 | |
| 14 | /* |
| 15 | * Simple Dequeueing Policy: |
| 16 | * If tx_qlen is different from 0, enqueue up to tx_qlen elements. |
| 17 | */ |
| 18 | static void qpolicy_simple_push(struct sock *sk, struct sk_buff *skb) |
| 19 | { |
| 20 | skb_queue_tail(&sk->sk_write_queue, skb); |
| 21 | } |
| 22 | |
| 23 | static bool qpolicy_simple_full(struct sock *sk) |
| 24 | { |
| 25 | return dccp_sk(sk)->dccps_tx_qlen && |
| 26 | sk->sk_write_queue.qlen >= dccp_sk(sk)->dccps_tx_qlen; |
| 27 | } |
| 28 | |
| 29 | static struct sk_buff *qpolicy_simple_top(struct sock *sk) |
| 30 | { |
| 31 | return skb_peek(&sk->sk_write_queue); |
| 32 | } |
| 33 | |
| 34 | /* |
| 35 | * Priority-based Dequeueing Policy: |
| 36 | * If tx_qlen is different from 0 and the queue has reached its upper bound |
| 37 | * of tx_qlen elements, replace older packets lowest-priority-first. |
| 38 | */ |
| 39 | static struct sk_buff *qpolicy_prio_best_skb(struct sock *sk) |
| 40 | { |
| 41 | struct sk_buff *skb, *best = NULL; |
| 42 | |
| 43 | skb_queue_walk(&sk->sk_write_queue, skb) |
| 44 | if (best == NULL || skb->priority > best->priority) |
| 45 | best = skb; |
| 46 | return best; |
| 47 | } |
| 48 | |
| 49 | static struct sk_buff *qpolicy_prio_worst_skb(struct sock *sk) |
| 50 | { |
| 51 | struct sk_buff *skb, *worst = NULL; |
| 52 | |
| 53 | skb_queue_walk(&sk->sk_write_queue, skb) |
| 54 | if (worst == NULL || skb->priority < worst->priority) |
| 55 | worst = skb; |
| 56 | return worst; |
| 57 | } |
| 58 | |
| 59 | static bool qpolicy_prio_full(struct sock *sk) |
| 60 | { |
| 61 | if (qpolicy_simple_full(sk)) |
| 62 | dccp_qpolicy_drop(sk, qpolicy_prio_worst_skb(sk)); |
| 63 | return false; |
| 64 | } |
| 65 | |
| 66 | /** |
| 67 | * struct dccp_qpolicy_operations - TX Packet Dequeueing Interface |
| 68 | * @push: add a new @skb to the write queue |
| 69 | * @full: indicates that no more packets will be admitted |
| 70 | * @top: peeks at whatever the queueing policy defines as its `top' |
| 71 | */ |
| 72 | static struct dccp_qpolicy_operations { |
| 73 | void (*push) (struct sock *sk, struct sk_buff *skb); |
| 74 | bool (*full) (struct sock *sk); |
| 75 | struct sk_buff* (*top) (struct sock *sk); |
| 76 | |
| 77 | } qpol_table[DCCPQ_POLICY_MAX] = { |
| 78 | [DCCPQ_POLICY_SIMPLE] = { |
| 79 | .push = qpolicy_simple_push, |
| 80 | .full = qpolicy_simple_full, |
| 81 | .top = qpolicy_simple_top, |
| 82 | }, |
| 83 | [DCCPQ_POLICY_PRIO] = { |
| 84 | .push = qpolicy_simple_push, |
| 85 | .full = qpolicy_prio_full, |
| 86 | .top = qpolicy_prio_best_skb, |
| 87 | }, |
| 88 | }; |
| 89 | |
| 90 | /* |
| 91 | * Externally visible interface |
| 92 | */ |
| 93 | void dccp_qpolicy_push(struct sock *sk, struct sk_buff *skb) |
| 94 | { |
| 95 | qpol_table[dccp_sk(sk)->dccps_qpolicy].push(sk, skb); |
| 96 | } |
| 97 | |
| 98 | bool dccp_qpolicy_full(struct sock *sk) |
| 99 | { |
| 100 | return qpol_table[dccp_sk(sk)->dccps_qpolicy].full(sk); |
| 101 | } |
| 102 | |
| 103 | void dccp_qpolicy_drop(struct sock *sk, struct sk_buff *skb) |
| 104 | { |
| 105 | if (skb != NULL) { |
| 106 | skb_unlink(skb, &sk->sk_write_queue); |
| 107 | kfree_skb(skb); |
| 108 | } |
| 109 | } |
| 110 | |
| 111 | struct sk_buff *dccp_qpolicy_top(struct sock *sk) |
| 112 | { |
| 113 | return qpol_table[dccp_sk(sk)->dccps_qpolicy].top(sk); |
| 114 | } |
| 115 | |
| 116 | struct sk_buff *dccp_qpolicy_pop(struct sock *sk) |
| 117 | { |
| 118 | struct sk_buff *skb = dccp_qpolicy_top(sk); |
| 119 | |
| 120 | if (skb != NULL) { |
| 121 | /* Clear any skb fields that we used internally */ |
| 122 | skb->priority = 0; |
| 123 | skb_unlink(skb, &sk->sk_write_queue); |
| 124 | } |
| 125 | return skb; |
| 126 | } |