[linux.git] / net / dccp / qpolicy.c

/*
 *  net/dccp/qpolicy.c
 *
 *  Policy-based packet dequeueing interface for DCCP.
 *
 *  Copyright (c) 2008 Tomasz Grobelny <[email protected]>
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License v2
 *  as published by the Free Software Foundation.
 */
#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'
 */
static 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;

} 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;
}
Commit	Line	Data
871a2c16 TG	1	/*
	2	* net/dccp/qpolicy.c
	3	*
	4	* Policy-based packet dequeueing interface for DCCP.
	5	*
	6	* Copyright (c) 2008 Tomasz Grobelny <[email protected]>
	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);
04910265	76	__be32 params;
871a2c16 TG	77
	78	} qpol_table[DCCPQ_POLICY_MAX] = {
	79	[DCCPQ_POLICY_SIMPLE] = {
04910265 TG	80	.push = qpolicy_simple_push,
	81	.full = qpolicy_simple_full,
	82	.top = qpolicy_simple_top,
	83	.params = 0,
871a2c16 TG	84	},
871a2c16 TG	85	[DCCPQ_POLICY_PRIO] = {
04910265 TG	86	.push = qpolicy_simple_push,
	87	.full = qpolicy_prio_full,
	88	.top = qpolicy_prio_best_skb,
	89	.params = DCCP_SCM_PRIORITY,
871a2c16 TG	90	},
	91	};
	92
	93	/*
	94	* Externally visible interface
	95	*/
	96	void dccp_qpolicy_push(struct sock sk, struct sk_buff skb)
	97	{
	98	qpol_table[dccp_sk(sk)->dccps_qpolicy].push(sk, skb);
	99	}
	100
	101	bool dccp_qpolicy_full(struct sock *sk)
	102	{
	103	return qpol_table[dccp_sk(sk)->dccps_qpolicy].full(sk);
	104	}
	105
	106	void dccp_qpolicy_drop(struct sock sk, struct sk_buff skb)
	107	{
	108	if (skb != NULL) {
	109	skb_unlink(skb, &sk->sk_write_queue);
	110	kfree_skb(skb);
	111	}
	112	}
	113
	114	struct sk_buff dccp_qpolicy_top(struct sock sk)
	115	{
	116	return qpol_table[dccp_sk(sk)->dccps_qpolicy].top(sk);
	117	}
	118
	119	struct sk_buff dccp_qpolicy_pop(struct sock sk)
	120	{
	121	struct sk_buff *skb = dccp_qpolicy_top(sk);
	122
	123	if (skb != NULL) {
	124	/* Clear any skb fields that we used internally */
	125	skb->priority = 0;
	126	skb_unlink(skb, &sk->sk_write_queue);
	127	}
	128	return skb;
	129	}
04910265 TG	130
	131	bool dccp_qpolicy_param_ok(struct sock *sk, __be32 param)
	132	{
	133	/* check if exactly one bit is set */
	134	if (!param \|\| (param & (param - 1)))
	135	return false;
	136	return (qpol_table[dccp_sk(sk)->dccps_qpolicy].params & param) == param;
	137	}