forked from torvalds/linux
-
Notifications
You must be signed in to change notification settings - Fork 4
/
qpolicy.c
136 lines (119 loc) · 3.29 KB
/
qpolicy.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
// SPDX-License-Identifier: GPL-2.0-only
/*
* net/dccp/qpolicy.c
*
* Policy-based packet dequeueing interface for DCCP.
*
* Copyright (c) 2008 Tomasz Grobelny <[email protected]>
*/
#include "dccp.h"
/*
* Simple Dequeueing Policy:
* If tx_qlen is different from 0, enqueue up to tx_qlen elements.
*/
static void qpolicy_simple_push(struct sock *sk, struct sk_buff *skb)
{
skb_queue_tail(&sk->sk_write_queue, skb);
}
static bool qpolicy_simple_full(struct sock *sk)
{
return dccp_sk(sk)->dccps_tx_qlen &&
sk->sk_write_queue.qlen >= dccp_sk(sk)->dccps_tx_qlen;
}
static struct sk_buff *qpolicy_simple_top(struct sock *sk)
{
return skb_peek(&sk->sk_write_queue);
}
/*
* Priority-based Dequeueing Policy:
* If tx_qlen is different from 0 and the queue has reached its upper bound
* of tx_qlen elements, replace older packets lowest-priority-first.
*/
static struct sk_buff *qpolicy_prio_best_skb(struct sock *sk)
{
struct sk_buff *skb, *best = NULL;
skb_queue_walk(&sk->sk_write_queue, skb)
if (best == NULL || skb->priority > best->priority)
best = skb;
return best;
}
static struct sk_buff *qpolicy_prio_worst_skb(struct sock *sk)
{
struct sk_buff *skb, *worst = NULL;
skb_queue_walk(&sk->sk_write_queue, skb)
if (worst == NULL || skb->priority < worst->priority)
worst = skb;
return worst;
}
static bool qpolicy_prio_full(struct sock *sk)
{
if (qpolicy_simple_full(sk))
dccp_qpolicy_drop(sk, qpolicy_prio_worst_skb(sk));
return false;
}
/**
* struct dccp_qpolicy_operations - TX Packet Dequeueing Interface
* @push: add a new @skb to the write queue
* @full: indicates that no more packets will be admitted
* @top: peeks at whatever the queueing policy defines as its `top'
* @params: parameter passed to policy operation
*/
struct dccp_qpolicy_operations {
void (*push) (struct sock *sk, struct sk_buff *skb);
bool (*full) (struct sock *sk);
struct sk_buff* (*top) (struct sock *sk);
__be32 params;
};
static struct dccp_qpolicy_operations qpol_table[DCCPQ_POLICY_MAX] = {
[DCCPQ_POLICY_SIMPLE] = {
.push = qpolicy_simple_push,
.full = qpolicy_simple_full,
.top = qpolicy_simple_top,
.params = 0,
},
[DCCPQ_POLICY_PRIO] = {
.push = qpolicy_simple_push,
.full = qpolicy_prio_full,
.top = qpolicy_prio_best_skb,
.params = DCCP_SCM_PRIORITY,
},
};
/*
* Externally visible interface
*/
void dccp_qpolicy_push(struct sock *sk, struct sk_buff *skb)
{
qpol_table[dccp_sk(sk)->dccps_qpolicy].push(sk, skb);
}
bool dccp_qpolicy_full(struct sock *sk)
{
return qpol_table[dccp_sk(sk)->dccps_qpolicy].full(sk);
}
void dccp_qpolicy_drop(struct sock *sk, struct sk_buff *skb)
{
if (skb != NULL) {
skb_unlink(skb, &sk->sk_write_queue);
kfree_skb(skb);
}
}
struct sk_buff *dccp_qpolicy_top(struct sock *sk)
{
return qpol_table[dccp_sk(sk)->dccps_qpolicy].top(sk);
}
struct sk_buff *dccp_qpolicy_pop(struct sock *sk)
{
struct sk_buff *skb = dccp_qpolicy_top(sk);
if (skb != NULL) {
/* Clear any skb fields that we used internally */
skb->priority = 0;
skb_unlink(skb, &sk->sk_write_queue);
}
return skb;
}
bool dccp_qpolicy_param_ok(struct sock *sk, __be32 param)
{
/* check if exactly one bit is set */
if (!param || (param & (param - 1)))
return false;
return (qpol_table[dccp_sk(sk)->dccps_qpolicy].params & param) == param;
}