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136 lines
3.3 KiB
136 lines
3.3 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* net/dccp/qpolicy.c |
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* |
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* Policy-based packet dequeueing interface for DCCP. |
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* |
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* Copyright (c) 2008 Tomasz Grobelny <[email protected]> |
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*/ |
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#include "dccp.h" |
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/* |
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* Simple Dequeueing Policy: |
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* If tx_qlen is different from 0, enqueue up to tx_qlen elements. |
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*/ |
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static void qpolicy_simple_push(struct sock *sk, struct sk_buff *skb) |
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{ |
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skb_queue_tail(&sk->sk_write_queue, skb); |
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} |
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static bool qpolicy_simple_full(struct sock *sk) |
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{ |
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return dccp_sk(sk)->dccps_tx_qlen && |
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sk->sk_write_queue.qlen >= dccp_sk(sk)->dccps_tx_qlen; |
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} |
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static struct sk_buff *qpolicy_simple_top(struct sock *sk) |
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{ |
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return skb_peek(&sk->sk_write_queue); |
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} |
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/* |
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* Priority-based Dequeueing Policy: |
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* If tx_qlen is different from 0 and the queue has reached its upper bound |
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* of tx_qlen elements, replace older packets lowest-priority-first. |
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*/ |
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static struct sk_buff *qpolicy_prio_best_skb(struct sock *sk) |
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{ |
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struct sk_buff *skb, *best = NULL; |
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skb_queue_walk(&sk->sk_write_queue, skb) |
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if (best == NULL || skb->priority > best->priority) |
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best = skb; |
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return best; |
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} |
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static struct sk_buff *qpolicy_prio_worst_skb(struct sock *sk) |
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{ |
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struct sk_buff *skb, *worst = NULL; |
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skb_queue_walk(&sk->sk_write_queue, skb) |
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if (worst == NULL || skb->priority < worst->priority) |
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worst = skb; |
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return worst; |
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} |
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static bool qpolicy_prio_full(struct sock *sk) |
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{ |
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if (qpolicy_simple_full(sk)) |
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dccp_qpolicy_drop(sk, qpolicy_prio_worst_skb(sk)); |
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return false; |
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} |
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/** |
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* struct dccp_qpolicy_operations - TX Packet Dequeueing Interface |
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* @push: add a new @skb to the write queue |
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* @full: indicates that no more packets will be admitted |
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* @top: peeks at whatever the queueing policy defines as its `top' |
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* @params: parameter passed to policy operation |
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*/ |
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struct dccp_qpolicy_operations { |
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void (*push) (struct sock *sk, struct sk_buff *skb); |
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bool (*full) (struct sock *sk); |
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struct sk_buff* (*top) (struct sock *sk); |
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__be32 params; |
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}; |
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static struct dccp_qpolicy_operations qpol_table[DCCPQ_POLICY_MAX] = { |
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[DCCPQ_POLICY_SIMPLE] = { |
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.push = qpolicy_simple_push, |
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.full = qpolicy_simple_full, |
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.top = qpolicy_simple_top, |
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.params = 0, |
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}, |
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[DCCPQ_POLICY_PRIO] = { |
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.push = qpolicy_simple_push, |
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.full = qpolicy_prio_full, |
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.top = qpolicy_prio_best_skb, |
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.params = DCCP_SCM_PRIORITY, |
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}, |
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}; |
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/* |
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* Externally visible interface |
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*/ |
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void dccp_qpolicy_push(struct sock *sk, struct sk_buff *skb) |
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{ |
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qpol_table[dccp_sk(sk)->dccps_qpolicy].push(sk, skb); |
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} |
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bool dccp_qpolicy_full(struct sock *sk) |
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{ |
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return qpol_table[dccp_sk(sk)->dccps_qpolicy].full(sk); |
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} |
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void dccp_qpolicy_drop(struct sock *sk, struct sk_buff *skb) |
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{ |
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if (skb != NULL) { |
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skb_unlink(skb, &sk->sk_write_queue); |
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kfree_skb(skb); |
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} |
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} |
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struct sk_buff *dccp_qpolicy_top(struct sock *sk) |
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{ |
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return qpol_table[dccp_sk(sk)->dccps_qpolicy].top(sk); |
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} |
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struct sk_buff *dccp_qpolicy_pop(struct sock *sk) |
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{ |
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struct sk_buff *skb = dccp_qpolicy_top(sk); |
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if (skb != NULL) { |
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/* Clear any skb fields that we used internally */ |
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skb->priority = 0; |
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skb_unlink(skb, &sk->sk_write_queue); |
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} |
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return skb; |
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} |
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bool dccp_qpolicy_param_ok(struct sock *sk, __be32 param) |
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{ |
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/* check if exactly one bit is set */ |
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if (!param || (param & (param - 1))) |
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return false; |
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return (qpol_table[dccp_sk(sk)->dccps_qpolicy].params & param) == param; |
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}
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