wme.c

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/*
 * Copyright 2004, Instant802 Networks, Inc.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/module.h>
#include <linux/if_arp.h>
#include <linux/types.h>
#include <net/ip.h>
#include <net/pkt_sched.h>

#include <net/mac80211.h>
#include "ieee80211_i.h"
#include "wme.h"

/* Default mapping in classifier to work with default
 * queue setup.
 */
const int ieee802_1d_to_ac[8] = {
        IEEE80211_AC_BE,
        IEEE80211_AC_BK,
        IEEE80211_AC_BK,
        IEEE80211_AC_BE,
        IEEE80211_AC_VI,
        IEEE80211_AC_VI,
        IEEE80211_AC_VO,
        IEEE80211_AC_VO
};

static int wme_downgrade_ac(struct sk_buff *skb)
{
        switch (skb->priority) {
        case 6:
        case 7:
                skb->priority = 5; /* VO -> VI */
                return 0;
        case 4:
        case 5:
                skb->priority = 3; /* VI -> BE */
                return 0;
        case 0:
        case 3:
                skb->priority = 2; /* BE -> BK */
                return 0;
        default:
                return -1;
        }
}


/* Indicate which queue to use. */
u16 ieee80211_select_queue(struct ieee80211_sub_if_data *sdata,
                           struct sk_buff *skb)
{
        struct ieee80211_local *local = sdata->local;
        struct sta_info *sta = NULL;
        const u8 *ra = NULL;
        bool qos = false;

        if (local->hw.queues < 4 || skb->len < 6) {
                skb->priority = 0; /* required for correct WPA/11i MIC */
                return min_t(u16, local->hw.queues - 1, IEEE80211_AC_BE);
        }

        rcu_read_lock();
        switch (sdata->vif.type) {
        case NL80211_IFTYPE_AP_VLAN:
                sta = rcu_dereference(sdata->u.vlan.sta);
                if (sta) {
                        qos = test_sta_flag(sta, WLAN_STA_WME);
                        break;
                }
        case NL80211_IFTYPE_AP:
                ra = skb->data;
                break;
        case NL80211_IFTYPE_WDS:
                ra = sdata->u.wds.remote_addr;
                break;
#ifdef CONFIG_MAC80211_MESH
        case NL80211_IFTYPE_MESH_POINT:
                ra = skb->data;
                break;
#endif
        case NL80211_IFTYPE_STATION:
                ra = sdata->u.mgd.bssid;
                break;
        case NL80211_IFTYPE_ADHOC:
                ra = skb->data;
                break;
        default:
                break;
        }

        if (!sta && ra && !is_multicast_ether_addr(ra)) {
                sta = sta_info_get(sdata, ra);
                if (sta)
                        qos = test_sta_flag(sta, WLAN_STA_WME);
        }
        rcu_read_unlock();

        if (!qos) {
                skb->priority = 0; /* required for correct WPA/11i MIC */
                return IEEE80211_AC_BE;
        }

        /* use the data classifier to determine what 802.1d tag the
         * data frame has */
        skb->priority = cfg80211_classify8021d(skb);

        return ieee80211_downgrade_queue(local, skb);
}

u16 ieee80211_downgrade_queue(struct ieee80211_local *local,
                              struct sk_buff *skb)
{
        /* in case we are a client verify acm is not set for this ac */
        while (unlikely(local->wmm_acm & BIT(skb->priority))) {
                if (wme_downgrade_ac(skb)) {
                        /*
                         * This should not really happen. The AP has marked all
                         * lower ACs to require admission control which is not
                         * a reasonable configuration. Allow the frame to be
                         * transmitted using AC_BK as a workaround.
                         */
                        break;
                }
        }

        /* look up which queue to use for frames with this 1d tag */
        return ieee802_1d_to_ac[skb->priority];
}

void ieee80211_set_qos_hdr(struct ieee80211_sub_if_data *sdata,
                           struct sk_buff *skb)
{
        struct ieee80211_hdr *hdr = (void *)skb->data;

        /* Fill in the QoS header if there is one. */
        if (ieee80211_is_data_qos(hdr->frame_control)) {
                u8 *p = ieee80211_get_qos_ctl(hdr);
                u8 ack_policy = 0, tid;

                tid = skb->priority & IEEE80211_QOS_CTL_TAG1D_MASK;

                if (unlikely(sdata->local->wifi_wme_noack_test))
                        ack_policy |= IEEE80211_QOS_CTL_ACK_POLICY_NOACK;
                /* qos header is 2 bytes */
                *p++ = ack_policy | tid;
                *p = ieee80211_vif_is_mesh(&sdata->vif) ?
                        (IEEE80211_QOS_CTL_MESH_CONTROL_PRESENT >> 8) : 0;
        }
}