wme.c revision 8f77f3849cc3ae2d6df9301785a3d316ea7d7ee1 
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 */
24const int ieee802_1d_to_ac[8] = { 2, 3, 3, 2, 1, 1, 0, 0 };
25
26static int wme_downgrade_ac(struct sk_buff *skb)
27{
28	switch (skb->priority) {
29	case 6:
30	case 7:
31		skb->priority = 5; /* VO -> VI */
32		return 0;
33	case 4:
34	case 5:
35		skb->priority = 3; /* VI -> BE */
36		return 0;
37	case 0:
38	case 3:
39		skb->priority = 2; /* BE -> BK */
40		return 0;
41	default:
42		return -1;
43	}
44}
45
46
47/* Indicate which queue to use.  */
48static u16 classify80211(struct ieee80211_local *local, struct sk_buff *skb)
49{
50	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
51
52	if (!ieee80211_is_data(hdr->frame_control)) {
53		/* management frames go on AC_VO queue, but are sent
54		* without QoS control fields */
55		return 0;
56	}
57
58	if (0 /* injected */) {
59		/* use AC from radiotap */
60	}
61
62	if (!ieee80211_is_data_qos(hdr->frame_control)) {
63		skb->priority = 0; /* required for correct WPA/11i MIC */
64		return ieee802_1d_to_ac[skb->priority];
65	}
66
67	/* use the data classifier to determine what 802.1d tag the
68	 * data frame has */
69	skb->priority = cfg80211_classify8021d(skb);
70
71	/* in case we are a client verify acm is not set for this ac */
72	while (unlikely(local->wmm_acm & BIT(skb->priority))) {
73		if (wme_downgrade_ac(skb)) {
74			/*
75			 * This should not really happen. The AP has marked all
76			 * lower ACs to require admission control which is not
77			 * a reasonable configuration. Allow the frame to be
78			 * transmitted using AC_BK as a workaround.
79			 */
80			break;
81		}
82	}
83
84	/* look up which queue to use for frames with this 1d tag */
85	return ieee802_1d_to_ac[skb->priority];
86}
87
88u16 ieee80211_select_queue(struct net_device *dev, struct sk_buff *skb)
89{
90	struct ieee80211_master_priv *mpriv = netdev_priv(dev);
91	struct ieee80211_local *local = mpriv->local;
92	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
93	u16 queue;
94	u8 tid;
95
96	queue = classify80211(local, skb);
97	if (unlikely(queue >= local->hw.queues))
98		queue = local->hw.queues - 1;
99
100	/*
101	 * Now we know the 1d priority, fill in the QoS header if
102	 * there is one (and we haven't done this before).
103	 */
104	if (ieee80211_is_data_qos(hdr->frame_control)) {
105		u8 *p = ieee80211_get_qos_ctl(hdr);
106		u8 ack_policy = 0;
107		tid = skb->priority & IEEE80211_QOS_CTL_TAG1D_MASK;
108		if (unlikely(local->wifi_wme_noack_test))
109			ack_policy |= QOS_CONTROL_ACK_POLICY_NOACK <<
110					QOS_CONTROL_ACK_POLICY_SHIFT;
111		/* qos header is 2 bytes, second reserved */
112		*p++ = ack_policy | tid;
113		*p = 0;
114	}
115
116	return queue;
117}
118