net/mac80211/wme.c

   1 /*
   2  * Copyright 2004, Instant802 Networks, Inc.
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  */
   8
   9 #include <linux/netdevice.h>
  10 #include <linux/skbuff.h>
  11 #include <linux/module.h>
  12 #include <linux/if_arp.h>
  13 #include <linux/types.h>
  14 #include <net/ip.h>
  15 #include <net/pkt_sched.h>
  16
  17 #include <net/mac80211.h>
  18 #include "ieee80211_i.h"
  19 #include "wme.h"
  20
  21 /* Default mapping in classifier to work with default
  22  * queue setup.
  23  */
  24 const int ieee802_1d_to_ac[8] = { 2, 3, 3, 2, 1, 1, 0, 0 };
  25
  26 static const char llc_ip_hdr[8] = {0xAA, 0xAA, 0x3, 0, 0, 0, 0x08, 0};
  27
  28 /* Given a data frame determine the 802.1p/1d tag to use.  */
  29 static unsigned int classify_1d(struct sk_buff *skb)
  30 {
  31         unsigned int dscp;
  32
  33         /* skb->priority values from 256->263 are magic values to
  34          * directly indicate a specific 802.1d priority.  This is used
  35          * to allow 802.1d priority to be passed directly in from VLAN
  36          * tags, etc.
  37          */
  38         if (skb->priority >= 256 && skb->priority <= 263)
  39                 return skb->priority - 256;
  40
  41         switch (skb->protocol) {
  42         case htons(ETH_P_IP):
  43                 dscp = ip_hdr(skb)->tos & 0xfc;
  44                 break;
  45
  46         default:
  47                 return 0;
  48         }
  49
  50         return dscp >> 5;
  51 }
  52
  53
  54 static int wme_downgrade_ac(struct sk_buff *skb)
  55 {
  56         switch (skb->priority) {
  57         case 6:
  58         case 7:
  59                 skb->priority = 5; /* VO -> VI */
  60                 return 0;
  61         case 4:
  62         case 5:
  63                 skb->priority = 3; /* VI -> BE */
  64                 return 0;
  65         case 0:
  66         case 3:
  67                 skb->priority = 2; /* BE -> BK */
  68                 return 0;
  69         default:
  70                 return -1;
  71         }
  72 }
  73
  74
  75 /* Indicate which queue to use.  */
  76 static u16 classify80211(struct ieee80211_local *local, struct sk_buff *skb)
  77 {
  78         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
  79
  80         if (!ieee80211_is_data(hdr->frame_control)) {
  81                 /* management frames go on AC_VO queue, but are sent
  82                 * without QoS control fields */
  83                 return 0;
  84         }
  85
  86         if (0 /* injected */) {
  87                 /* use AC from radiotap */
  88         }
  89
  90         if (!ieee80211_is_data_qos(hdr->frame_control)) {
  91                 skb->priority = 0; /* required for correct WPA/11i MIC */
  92                 return ieee802_1d_to_ac[skb->priority];
  93         }
  94
  95         /* use the data classifier to determine what 802.1d tag the
  96          * data frame has */
  97         skb->priority = classify_1d(skb);
  98
  99         /* in case we are a client verify acm is not set for this ac */
 100         while (unlikely(local->wmm_acm & BIT(skb->priority))) {
 101                 if (wme_downgrade_ac(skb)) {
 102                         /*
 103                          * This should not really happen. The AP has marked all
 104                          * lower ACs to require admission control which is not
 105                          * a reasonable configuration. Allow the frame to be
 106                          * transmitted using AC_BK as a workaround.
 107                          */
 108                         break;
 109                 }
 110         }
 111
 112         /* look up which queue to use for frames with this 1d tag */
 113         return ieee802_1d_to_ac[skb->priority];
 114 }
 115
 116 u16 ieee80211_select_queue(struct net_device *dev, struct sk_buff *skb)
 117 {
 118         struct ieee80211_master_priv *mpriv = netdev_priv(dev);
 119         struct ieee80211_local *local = mpriv->local;
 120         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
 121         u16 queue;
 122         u8 tid;
 123
 124         queue = classify80211(local, skb);
 125         if (unlikely(queue >= local->hw.queues))
 126                 queue = local->hw.queues - 1;
 127
 128         /*
 129          * Now we know the 1d priority, fill in the QoS header if
 130          * there is one (and we haven't done this before).
 131          */
 132         if (!skb->requeue && ieee80211_is_data_qos(hdr->frame_control)) {
 133                 u8 *p = ieee80211_get_qos_ctl(hdr);
 134                 u8 ack_policy = 0;
 135                 tid = skb->priority & IEEE80211_QOS_CTL_TAG1D_MASK;
 136                 if (local->wifi_wme_noack_test)
 137                         ack_policy |= QOS_CONTROL_ACK_POLICY_NOACK <<
 138                                         QOS_CONTROL_ACK_POLICY_SHIFT;
 139                 /* qos header is 2 bytes, second reserved */
 140                 *p++ = ack_policy | tid;
 141                 *p = 0;
 142         }
 143
 144         return queue;
 145 }