// SPDX-License-Identifier: GPL-2.0-only /* * net/dccp/qpolicy.c * * Policy-based packet dequeueing interface for DCCP. * * Copyright (c) 2008 Tomasz Grobelny <tomasz@grobelny.oswiecenia.net> */ #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; }