![David S. Miller](/assets/img/avatar_default.png)
Just like skb->cb[], so that qdisc_skb_cb can be encapsulated inside of other data structures. This is intended to be used by IPoIB so that it can remember addressing information stored at hard_header_ops->create() time that it can fetch when the packet gets to the transmit routine. Signed-off-by: David S. Miller <davem@davemloft.net>
645 lines
15 KiB
C
645 lines
15 KiB
C
/*
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* net/sched/sch_choke.c CHOKE scheduler
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*
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* Copyright (c) 2011 Stephen Hemminger <shemminger@vyatta.com>
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* Copyright (c) 2011 Eric Dumazet <eric.dumazet@gmail.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* version 2 as published by the Free Software Foundation.
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*
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*/
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#include <linux/module.h>
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#include <linux/types.h>
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#include <linux/kernel.h>
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#include <linux/skbuff.h>
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#include <linux/reciprocal_div.h>
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#include <linux/vmalloc.h>
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#include <net/pkt_sched.h>
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#include <net/inet_ecn.h>
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#include <net/red.h>
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#include <net/flow_keys.h>
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/*
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CHOKe stateless AQM for fair bandwidth allocation
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=================================================
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CHOKe (CHOose and Keep for responsive flows, CHOose and Kill for
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unresponsive flows) is a variant of RED that penalizes misbehaving flows but
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maintains no flow state. The difference from RED is an additional step
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during the enqueuing process. If average queue size is over the
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low threshold (qmin), a packet is chosen at random from the queue.
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If both the new and chosen packet are from the same flow, both
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are dropped. Unlike RED, CHOKe is not really a "classful" qdisc because it
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needs to access packets in queue randomly. It has a minimal class
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interface to allow overriding the builtin flow classifier with
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filters.
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Source:
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R. Pan, B. Prabhakar, and K. Psounis, "CHOKe, A Stateless
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Active Queue Management Scheme for Approximating Fair Bandwidth Allocation",
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IEEE INFOCOM, 2000.
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A. Tang, J. Wang, S. Low, "Understanding CHOKe: Throughput and Spatial
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Characteristics", IEEE/ACM Transactions on Networking, 2004
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*/
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/* Upper bound on size of sk_buff table (packets) */
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#define CHOKE_MAX_QUEUE (128*1024 - 1)
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struct choke_sched_data {
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/* Parameters */
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u32 limit;
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unsigned char flags;
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struct red_parms parms;
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/* Variables */
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struct red_vars vars;
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struct tcf_proto *filter_list;
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struct {
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u32 prob_drop; /* Early probability drops */
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u32 prob_mark; /* Early probability marks */
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u32 forced_drop; /* Forced drops, qavg > max_thresh */
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u32 forced_mark; /* Forced marks, qavg > max_thresh */
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u32 pdrop; /* Drops due to queue limits */
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u32 other; /* Drops due to drop() calls */
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u32 matched; /* Drops to flow match */
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} stats;
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unsigned int head;
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unsigned int tail;
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unsigned int tab_mask; /* size - 1 */
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struct sk_buff **tab;
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};
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/* deliver a random number between 0 and N - 1 */
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static u32 random_N(unsigned int N)
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{
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return reciprocal_divide(random32(), N);
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}
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/* number of elements in queue including holes */
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static unsigned int choke_len(const struct choke_sched_data *q)
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{
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return (q->tail - q->head) & q->tab_mask;
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}
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/* Is ECN parameter configured */
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static int use_ecn(const struct choke_sched_data *q)
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{
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return q->flags & TC_RED_ECN;
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}
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/* Should packets over max just be dropped (versus marked) */
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static int use_harddrop(const struct choke_sched_data *q)
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{
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return q->flags & TC_RED_HARDDROP;
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}
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/* Move head pointer forward to skip over holes */
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static void choke_zap_head_holes(struct choke_sched_data *q)
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{
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do {
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q->head = (q->head + 1) & q->tab_mask;
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if (q->head == q->tail)
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break;
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} while (q->tab[q->head] == NULL);
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}
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/* Move tail pointer backwards to reuse holes */
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static void choke_zap_tail_holes(struct choke_sched_data *q)
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{
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do {
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q->tail = (q->tail - 1) & q->tab_mask;
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if (q->head == q->tail)
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break;
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} while (q->tab[q->tail] == NULL);
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}
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/* Drop packet from queue array by creating a "hole" */
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static void choke_drop_by_idx(struct Qdisc *sch, unsigned int idx)
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{
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struct choke_sched_data *q = qdisc_priv(sch);
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struct sk_buff *skb = q->tab[idx];
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q->tab[idx] = NULL;
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if (idx == q->head)
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choke_zap_head_holes(q);
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if (idx == q->tail)
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choke_zap_tail_holes(q);
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sch->qstats.backlog -= qdisc_pkt_len(skb);
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qdisc_drop(skb, sch);
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qdisc_tree_decrease_qlen(sch, 1);
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--sch->q.qlen;
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}
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struct choke_skb_cb {
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u16 classid;
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u8 keys_valid;
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struct flow_keys keys;
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};
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static inline struct choke_skb_cb *choke_skb_cb(const struct sk_buff *skb)
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{
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qdisc_cb_private_validate(skb, sizeof(struct choke_skb_cb));
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return (struct choke_skb_cb *)qdisc_skb_cb(skb)->data;
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}
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static inline void choke_set_classid(struct sk_buff *skb, u16 classid)
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{
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choke_skb_cb(skb)->classid = classid;
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}
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static u16 choke_get_classid(const struct sk_buff *skb)
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{
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return choke_skb_cb(skb)->classid;
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}
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/*
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* Compare flow of two packets
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* Returns true only if source and destination address and port match.
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* false for special cases
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*/
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static bool choke_match_flow(struct sk_buff *skb1,
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struct sk_buff *skb2)
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{
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if (skb1->protocol != skb2->protocol)
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return false;
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if (!choke_skb_cb(skb1)->keys_valid) {
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choke_skb_cb(skb1)->keys_valid = 1;
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skb_flow_dissect(skb1, &choke_skb_cb(skb1)->keys);
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}
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if (!choke_skb_cb(skb2)->keys_valid) {
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choke_skb_cb(skb2)->keys_valid = 1;
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skb_flow_dissect(skb2, &choke_skb_cb(skb2)->keys);
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}
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return !memcmp(&choke_skb_cb(skb1)->keys,
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&choke_skb_cb(skb2)->keys,
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sizeof(struct flow_keys));
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}
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/*
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* Classify flow using either:
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* 1. pre-existing classification result in skb
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* 2. fast internal classification
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* 3. use TC filter based classification
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*/
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static bool choke_classify(struct sk_buff *skb,
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struct Qdisc *sch, int *qerr)
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{
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struct choke_sched_data *q = qdisc_priv(sch);
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struct tcf_result res;
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int result;
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result = tc_classify(skb, q->filter_list, &res);
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if (result >= 0) {
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#ifdef CONFIG_NET_CLS_ACT
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switch (result) {
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case TC_ACT_STOLEN:
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case TC_ACT_QUEUED:
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*qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
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case TC_ACT_SHOT:
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return false;
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}
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#endif
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choke_set_classid(skb, TC_H_MIN(res.classid));
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return true;
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}
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return false;
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}
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/*
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* Select a packet at random from queue
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* HACK: since queue can have holes from previous deletion; retry several
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* times to find a random skb but then just give up and return the head
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* Will return NULL if queue is empty (q->head == q->tail)
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*/
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static struct sk_buff *choke_peek_random(const struct choke_sched_data *q,
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unsigned int *pidx)
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{
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struct sk_buff *skb;
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int retrys = 3;
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do {
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*pidx = (q->head + random_N(choke_len(q))) & q->tab_mask;
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skb = q->tab[*pidx];
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if (skb)
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return skb;
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} while (--retrys > 0);
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return q->tab[*pidx = q->head];
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}
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/*
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* Compare new packet with random packet in queue
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* returns true if matched and sets *pidx
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*/
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static bool choke_match_random(const struct choke_sched_data *q,
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struct sk_buff *nskb,
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unsigned int *pidx)
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{
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struct sk_buff *oskb;
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if (q->head == q->tail)
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return false;
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oskb = choke_peek_random(q, pidx);
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if (q->filter_list)
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return choke_get_classid(nskb) == choke_get_classid(oskb);
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return choke_match_flow(oskb, nskb);
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}
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static int choke_enqueue(struct sk_buff *skb, struct Qdisc *sch)
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{
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struct choke_sched_data *q = qdisc_priv(sch);
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const struct red_parms *p = &q->parms;
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int ret = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
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if (q->filter_list) {
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/* If using external classifiers, get result and record it. */
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if (!choke_classify(skb, sch, &ret))
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goto other_drop; /* Packet was eaten by filter */
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}
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choke_skb_cb(skb)->keys_valid = 0;
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/* Compute average queue usage (see RED) */
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q->vars.qavg = red_calc_qavg(p, &q->vars, sch->q.qlen);
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if (red_is_idling(&q->vars))
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red_end_of_idle_period(&q->vars);
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/* Is queue small? */
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if (q->vars.qavg <= p->qth_min)
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q->vars.qcount = -1;
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else {
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unsigned int idx;
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/* Draw a packet at random from queue and compare flow */
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if (choke_match_random(q, skb, &idx)) {
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q->stats.matched++;
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choke_drop_by_idx(sch, idx);
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goto congestion_drop;
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}
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/* Queue is large, always mark/drop */
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if (q->vars.qavg > p->qth_max) {
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q->vars.qcount = -1;
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sch->qstats.overlimits++;
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if (use_harddrop(q) || !use_ecn(q) ||
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!INET_ECN_set_ce(skb)) {
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q->stats.forced_drop++;
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goto congestion_drop;
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}
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q->stats.forced_mark++;
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} else if (++q->vars.qcount) {
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if (red_mark_probability(p, &q->vars, q->vars.qavg)) {
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q->vars.qcount = 0;
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q->vars.qR = red_random(p);
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sch->qstats.overlimits++;
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if (!use_ecn(q) || !INET_ECN_set_ce(skb)) {
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q->stats.prob_drop++;
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goto congestion_drop;
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}
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q->stats.prob_mark++;
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}
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} else
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q->vars.qR = red_random(p);
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}
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/* Admit new packet */
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if (sch->q.qlen < q->limit) {
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q->tab[q->tail] = skb;
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q->tail = (q->tail + 1) & q->tab_mask;
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++sch->q.qlen;
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sch->qstats.backlog += qdisc_pkt_len(skb);
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return NET_XMIT_SUCCESS;
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}
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q->stats.pdrop++;
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sch->qstats.drops++;
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kfree_skb(skb);
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return NET_XMIT_DROP;
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congestion_drop:
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qdisc_drop(skb, sch);
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return NET_XMIT_CN;
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other_drop:
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if (ret & __NET_XMIT_BYPASS)
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sch->qstats.drops++;
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kfree_skb(skb);
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return ret;
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}
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static struct sk_buff *choke_dequeue(struct Qdisc *sch)
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{
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struct choke_sched_data *q = qdisc_priv(sch);
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struct sk_buff *skb;
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if (q->head == q->tail) {
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if (!red_is_idling(&q->vars))
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red_start_of_idle_period(&q->vars);
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return NULL;
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}
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skb = q->tab[q->head];
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q->tab[q->head] = NULL;
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choke_zap_head_holes(q);
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--sch->q.qlen;
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sch->qstats.backlog -= qdisc_pkt_len(skb);
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qdisc_bstats_update(sch, skb);
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return skb;
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}
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static unsigned int choke_drop(struct Qdisc *sch)
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{
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struct choke_sched_data *q = qdisc_priv(sch);
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unsigned int len;
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len = qdisc_queue_drop(sch);
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if (len > 0)
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q->stats.other++;
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else {
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if (!red_is_idling(&q->vars))
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red_start_of_idle_period(&q->vars);
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}
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return len;
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}
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static void choke_reset(struct Qdisc *sch)
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{
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struct choke_sched_data *q = qdisc_priv(sch);
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red_restart(&q->vars);
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}
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static const struct nla_policy choke_policy[TCA_CHOKE_MAX + 1] = {
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[TCA_CHOKE_PARMS] = { .len = sizeof(struct tc_red_qopt) },
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[TCA_CHOKE_STAB] = { .len = RED_STAB_SIZE },
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[TCA_CHOKE_MAX_P] = { .type = NLA_U32 },
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};
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static void choke_free(void *addr)
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{
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if (addr) {
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if (is_vmalloc_addr(addr))
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vfree(addr);
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else
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kfree(addr);
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}
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}
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static int choke_change(struct Qdisc *sch, struct nlattr *opt)
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{
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struct choke_sched_data *q = qdisc_priv(sch);
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struct nlattr *tb[TCA_CHOKE_MAX + 1];
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const struct tc_red_qopt *ctl;
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int err;
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struct sk_buff **old = NULL;
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unsigned int mask;
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u32 max_P;
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if (opt == NULL)
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return -EINVAL;
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err = nla_parse_nested(tb, TCA_CHOKE_MAX, opt, choke_policy);
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if (err < 0)
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return err;
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if (tb[TCA_CHOKE_PARMS] == NULL ||
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tb[TCA_CHOKE_STAB] == NULL)
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return -EINVAL;
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max_P = tb[TCA_CHOKE_MAX_P] ? nla_get_u32(tb[TCA_CHOKE_MAX_P]) : 0;
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ctl = nla_data(tb[TCA_CHOKE_PARMS]);
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if (ctl->limit > CHOKE_MAX_QUEUE)
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return -EINVAL;
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mask = roundup_pow_of_two(ctl->limit + 1) - 1;
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if (mask != q->tab_mask) {
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struct sk_buff **ntab;
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ntab = kcalloc(mask + 1, sizeof(struct sk_buff *), GFP_KERNEL);
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if (!ntab)
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ntab = vzalloc((mask + 1) * sizeof(struct sk_buff *));
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if (!ntab)
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return -ENOMEM;
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sch_tree_lock(sch);
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old = q->tab;
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if (old) {
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unsigned int oqlen = sch->q.qlen, tail = 0;
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while (q->head != q->tail) {
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struct sk_buff *skb = q->tab[q->head];
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q->head = (q->head + 1) & q->tab_mask;
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if (!skb)
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continue;
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if (tail < mask) {
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ntab[tail++] = skb;
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continue;
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}
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sch->qstats.backlog -= qdisc_pkt_len(skb);
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--sch->q.qlen;
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qdisc_drop(skb, sch);
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}
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qdisc_tree_decrease_qlen(sch, oqlen - sch->q.qlen);
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q->head = 0;
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q->tail = tail;
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}
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q->tab_mask = mask;
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q->tab = ntab;
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} else
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sch_tree_lock(sch);
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q->flags = ctl->flags;
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q->limit = ctl->limit;
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red_set_parms(&q->parms, ctl->qth_min, ctl->qth_max, ctl->Wlog,
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ctl->Plog, ctl->Scell_log,
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nla_data(tb[TCA_CHOKE_STAB]),
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max_P);
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red_set_vars(&q->vars);
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if (q->head == q->tail)
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red_end_of_idle_period(&q->vars);
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sch_tree_unlock(sch);
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choke_free(old);
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return 0;
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}
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static int choke_init(struct Qdisc *sch, struct nlattr *opt)
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{
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return choke_change(sch, opt);
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}
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static int choke_dump(struct Qdisc *sch, struct sk_buff *skb)
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{
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struct choke_sched_data *q = qdisc_priv(sch);
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struct nlattr *opts = NULL;
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struct tc_red_qopt opt = {
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.limit = q->limit,
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.flags = q->flags,
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.qth_min = q->parms.qth_min >> q->parms.Wlog,
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.qth_max = q->parms.qth_max >> q->parms.Wlog,
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.Wlog = q->parms.Wlog,
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.Plog = q->parms.Plog,
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.Scell_log = q->parms.Scell_log,
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};
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opts = nla_nest_start(skb, TCA_OPTIONS);
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if (opts == NULL)
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goto nla_put_failure;
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NLA_PUT(skb, TCA_CHOKE_PARMS, sizeof(opt), &opt);
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NLA_PUT_U32(skb, TCA_CHOKE_MAX_P, q->parms.max_P);
|
|
return nla_nest_end(skb, opts);
|
|
|
|
nla_put_failure:
|
|
nla_nest_cancel(skb, opts);
|
|
return -EMSGSIZE;
|
|
}
|
|
|
|
static int choke_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
|
|
{
|
|
struct choke_sched_data *q = qdisc_priv(sch);
|
|
struct tc_choke_xstats st = {
|
|
.early = q->stats.prob_drop + q->stats.forced_drop,
|
|
.marked = q->stats.prob_mark + q->stats.forced_mark,
|
|
.pdrop = q->stats.pdrop,
|
|
.other = q->stats.other,
|
|
.matched = q->stats.matched,
|
|
};
|
|
|
|
return gnet_stats_copy_app(d, &st, sizeof(st));
|
|
}
|
|
|
|
static void choke_destroy(struct Qdisc *sch)
|
|
{
|
|
struct choke_sched_data *q = qdisc_priv(sch);
|
|
|
|
tcf_destroy_chain(&q->filter_list);
|
|
choke_free(q->tab);
|
|
}
|
|
|
|
static struct Qdisc *choke_leaf(struct Qdisc *sch, unsigned long arg)
|
|
{
|
|
return NULL;
|
|
}
|
|
|
|
static unsigned long choke_get(struct Qdisc *sch, u32 classid)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
static void choke_put(struct Qdisc *q, unsigned long cl)
|
|
{
|
|
}
|
|
|
|
static unsigned long choke_bind(struct Qdisc *sch, unsigned long parent,
|
|
u32 classid)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
static struct tcf_proto **choke_find_tcf(struct Qdisc *sch, unsigned long cl)
|
|
{
|
|
struct choke_sched_data *q = qdisc_priv(sch);
|
|
|
|
if (cl)
|
|
return NULL;
|
|
return &q->filter_list;
|
|
}
|
|
|
|
static int choke_dump_class(struct Qdisc *sch, unsigned long cl,
|
|
struct sk_buff *skb, struct tcmsg *tcm)
|
|
{
|
|
tcm->tcm_handle |= TC_H_MIN(cl);
|
|
return 0;
|
|
}
|
|
|
|
static void choke_walk(struct Qdisc *sch, struct qdisc_walker *arg)
|
|
{
|
|
if (!arg->stop) {
|
|
if (arg->fn(sch, 1, arg) < 0) {
|
|
arg->stop = 1;
|
|
return;
|
|
}
|
|
arg->count++;
|
|
}
|
|
}
|
|
|
|
static const struct Qdisc_class_ops choke_class_ops = {
|
|
.leaf = choke_leaf,
|
|
.get = choke_get,
|
|
.put = choke_put,
|
|
.tcf_chain = choke_find_tcf,
|
|
.bind_tcf = choke_bind,
|
|
.unbind_tcf = choke_put,
|
|
.dump = choke_dump_class,
|
|
.walk = choke_walk,
|
|
};
|
|
|
|
static struct sk_buff *choke_peek_head(struct Qdisc *sch)
|
|
{
|
|
struct choke_sched_data *q = qdisc_priv(sch);
|
|
|
|
return (q->head != q->tail) ? q->tab[q->head] : NULL;
|
|
}
|
|
|
|
static struct Qdisc_ops choke_qdisc_ops __read_mostly = {
|
|
.id = "choke",
|
|
.priv_size = sizeof(struct choke_sched_data),
|
|
|
|
.enqueue = choke_enqueue,
|
|
.dequeue = choke_dequeue,
|
|
.peek = choke_peek_head,
|
|
.drop = choke_drop,
|
|
.init = choke_init,
|
|
.destroy = choke_destroy,
|
|
.reset = choke_reset,
|
|
.change = choke_change,
|
|
.dump = choke_dump,
|
|
.dump_stats = choke_dump_stats,
|
|
.owner = THIS_MODULE,
|
|
};
|
|
|
|
static int __init choke_module_init(void)
|
|
{
|
|
return register_qdisc(&choke_qdisc_ops);
|
|
}
|
|
|
|
static void __exit choke_module_exit(void)
|
|
{
|
|
unregister_qdisc(&choke_qdisc_ops);
|
|
}
|
|
|
|
module_init(choke_module_init)
|
|
module_exit(choke_module_exit)
|
|
|
|
MODULE_LICENSE("GPL");
|