cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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qpolicy.c (3367B)

      1// SPDX-License-Identifier: GPL-2.0-only
      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>
      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 */
     15static void qpolicy_simple_push(struct sock *sk, struct sk_buff *skb)
     16{
     17	skb_queue_tail(&sk->sk_write_queue, skb);
     18}
     19
     20static 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
     26static 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 */
     36static 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
     46static 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
     56static 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'
     68 * @params: parameter passed to policy operation
     69 */
     70struct dccp_qpolicy_operations {
     71	void		(*push)	(struct sock *sk, struct sk_buff *skb);
     72	bool		(*full) (struct sock *sk);
     73	struct sk_buff*	(*top)  (struct sock *sk);
     74	__be32		params;
     75};
     76
     77static struct dccp_qpolicy_operations 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		.params = 0,
     83	},
     84	[DCCPQ_POLICY_PRIO] = {
     85		.push   = qpolicy_simple_push,
     86		.full   = qpolicy_prio_full,
     87		.top    = qpolicy_prio_best_skb,
     88		.params = DCCP_SCM_PRIORITY,
     89	},
     90};
     91
     92/*
     93 *	Externally visible interface
     94 */
     95void dccp_qpolicy_push(struct sock *sk, struct sk_buff *skb)
     96{
     97	qpol_table[dccp_sk(sk)->dccps_qpolicy].push(sk, skb);
     98}
     99
    100bool dccp_qpolicy_full(struct sock *sk)
    101{
    102	return qpol_table[dccp_sk(sk)->dccps_qpolicy].full(sk);
    103}
    104
    105void 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
    113struct sk_buff *dccp_qpolicy_top(struct sock *sk)
    114{
    115	return qpol_table[dccp_sk(sk)->dccps_qpolicy].top(sk);
    116}
    117
    118struct 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}
    129
    130bool 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}