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e46bd709 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
871a2c16 TG |
2 | /* |
3 | * net/dccp/qpolicy.c | |
4 | * | |
5 | * Policy-based packet dequeueing interface for DCCP. | |
6 | * | |
7 | * Copyright (c) 2008 Tomasz Grobelny <tomasz@grobelny.oswiecenia.net> | |
871a2c16 TG |
8 | */ |
9 | #include "dccp.h" | |
10 | ||
11 | /* | |
12 | * Simple Dequeueing Policy: | |
13 | * If tx_qlen is different from 0, enqueue up to tx_qlen elements. | |
14 | */ | |
15 | static void qpolicy_simple_push(struct sock *sk, struct sk_buff *skb) | |
16 | { | |
17 | skb_queue_tail(&sk->sk_write_queue, skb); | |
18 | } | |
19 | ||
20 | static bool qpolicy_simple_full(struct sock *sk) | |
21 | { | |
22 | return dccp_sk(sk)->dccps_tx_qlen && | |
23 | sk->sk_write_queue.qlen >= dccp_sk(sk)->dccps_tx_qlen; | |
24 | } | |
25 | ||
26 | static struct sk_buff *qpolicy_simple_top(struct sock *sk) | |
27 | { | |
28 | return skb_peek(&sk->sk_write_queue); | |
29 | } | |
30 | ||
31 | /* | |
32 | * Priority-based Dequeueing Policy: | |
33 | * If tx_qlen is different from 0 and the queue has reached its upper bound | |
34 | * of tx_qlen elements, replace older packets lowest-priority-first. | |
35 | */ | |
36 | static struct sk_buff *qpolicy_prio_best_skb(struct sock *sk) | |
37 | { | |
38 | struct sk_buff *skb, *best = NULL; | |
39 | ||
40 | skb_queue_walk(&sk->sk_write_queue, skb) | |
41 | if (best == NULL || skb->priority > best->priority) | |
42 | best = skb; | |
43 | return best; | |
44 | } | |
45 | ||
46 | static struct sk_buff *qpolicy_prio_worst_skb(struct sock *sk) | |
47 | { | |
48 | struct sk_buff *skb, *worst = NULL; | |
49 | ||
50 | skb_queue_walk(&sk->sk_write_queue, skb) | |
51 | if (worst == NULL || skb->priority < worst->priority) | |
52 | worst = skb; | |
53 | return worst; | |
54 | } | |
55 | ||
56 | static bool qpolicy_prio_full(struct sock *sk) | |
57 | { | |
58 | if (qpolicy_simple_full(sk)) | |
59 | dccp_qpolicy_drop(sk, qpolicy_prio_worst_skb(sk)); | |
60 | return false; | |
61 | } | |
62 | ||
63 | /** | |
64 | * struct dccp_qpolicy_operations - TX Packet Dequeueing Interface | |
65 | * @push: add a new @skb to the write queue | |
66 | * @full: indicates that no more packets will be admitted | |
67 | * @top: peeks at whatever the queueing policy defines as its `top' | |
0b609b55 | 68 | * @params: parameter passed to policy operation |
871a2c16 | 69 | */ |
0b609b55 | 70 | struct dccp_qpolicy_operations { |
871a2c16 TG |
71 | void (*push) (struct sock *sk, struct sk_buff *skb); |
72 | bool (*full) (struct sock *sk); | |
73 | struct sk_buff* (*top) (struct sock *sk); | |
04910265 | 74 | __be32 params; |
0b609b55 | 75 | }; |
871a2c16 | 76 | |
0b609b55 | 77 | static struct dccp_qpolicy_operations qpol_table[DCCPQ_POLICY_MAX] = { |
871a2c16 | 78 | [DCCPQ_POLICY_SIMPLE] = { |
04910265 TG |
79 | .push = qpolicy_simple_push, |
80 | .full = qpolicy_simple_full, | |
81 | .top = qpolicy_simple_top, | |
82 | .params = 0, | |
871a2c16 TG |
83 | }, |
84 | [DCCPQ_POLICY_PRIO] = { | |
04910265 TG |
85 | .push = qpolicy_simple_push, |
86 | .full = qpolicy_prio_full, | |
87 | .top = qpolicy_prio_best_skb, | |
88 | .params = DCCP_SCM_PRIORITY, | |
871a2c16 TG |
89 | }, |
90 | }; | |
91 | ||
92 | /* | |
93 | * Externally visible interface | |
94 | */ | |
95 | void dccp_qpolicy_push(struct sock *sk, struct sk_buff *skb) | |
96 | { | |
97 | qpol_table[dccp_sk(sk)->dccps_qpolicy].push(sk, skb); | |
98 | } | |
99 | ||
100 | bool dccp_qpolicy_full(struct sock *sk) | |
101 | { | |
102 | return qpol_table[dccp_sk(sk)->dccps_qpolicy].full(sk); | |
103 | } | |
104 | ||
105 | void dccp_qpolicy_drop(struct sock *sk, struct sk_buff *skb) | |
106 | { | |
107 | if (skb != NULL) { | |
108 | skb_unlink(skb, &sk->sk_write_queue); | |
109 | kfree_skb(skb); | |
110 | } | |
111 | } | |
112 | ||
113 | struct sk_buff *dccp_qpolicy_top(struct sock *sk) | |
114 | { | |
115 | return qpol_table[dccp_sk(sk)->dccps_qpolicy].top(sk); | |
116 | } | |
117 | ||
118 | struct sk_buff *dccp_qpolicy_pop(struct sock *sk) | |
119 | { | |
120 | struct sk_buff *skb = dccp_qpolicy_top(sk); | |
121 | ||
122 | if (skb != NULL) { | |
123 | /* Clear any skb fields that we used internally */ | |
124 | skb->priority = 0; | |
125 | skb_unlink(skb, &sk->sk_write_queue); | |
126 | } | |
127 | return skb; | |
128 | } | |
04910265 TG |
129 | |
130 | bool dccp_qpolicy_param_ok(struct sock *sk, __be32 param) | |
131 | { | |
132 | /* check if exactly one bit is set */ | |
133 | if (!param || (param & (param - 1))) | |
134 | return false; | |
135 | return (qpol_table[dccp_sk(sk)->dccps_qpolicy].params & param) == param; | |
136 | } |