linux/net/mac80211/wme.c
Jouni Malinen 0eeb59fe2c mac80211: Fix WMM ACM parsing and AC downgrade operation
Incorrect local->wmm_acm bits were set for AC_BK and AC_BE. Fix this
and add some comments to make it easier to understand the AC-to-UP(pair)
mapping. Set the wmm_acm bits (and show WMM debug) even if the driver
does not implement conf_tx() handler.

In addition, fix the ACM-based AC downgrade code to not use the
highest priority in error cases. We need to break the loop to get the
correct AC_BK value (3) instead of returning 0 (which would indicate
AC_VO). The comment here was not really very useful either, so let's
provide somewhat more helpful description of the situation.

Since it is very unlikely that the ACM flag would be set for AC_BK and
AC_BE, these bugs are not likely to be seen in real life networks.
Anyway, better do these things correctly should someone really use
silly AP configuration (and to pass some functionality tests, too).

Remove the TODO comment about handling ACM. Downgrading AC is
perfectly valid mechanism for ACM. Eventually, we may add support for
WMM-AC and send a request for a TS, but anyway, that functionality
won't be here at the location of this TODO comment.

Signed-off-by: Jouni Malinen <jouni.malinen@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
2009-03-16 18:09:27 -04:00

146 lines
3.6 KiB
C

/*
* 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] = { 2, 3, 3, 2, 1, 1, 0, 0 };
static const char llc_ip_hdr[8] = {0xAA, 0xAA, 0x3, 0, 0, 0, 0x08, 0};
/* Given a data frame determine the 802.1p/1d tag to use. */
static unsigned int classify_1d(struct sk_buff *skb)
{
unsigned int dscp;
/* skb->priority values from 256->263 are magic values to
* directly indicate a specific 802.1d priority. This is used
* to allow 802.1d priority to be passed directly in from VLAN
* tags, etc.
*/
if (skb->priority >= 256 && skb->priority <= 263)
return skb->priority - 256;
switch (skb->protocol) {
case htons(ETH_P_IP):
dscp = ip_hdr(skb)->tos & 0xfc;
break;
default:
return 0;
}
return dscp >> 5;
}
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. */
static u16 classify80211(struct ieee80211_local *local, struct sk_buff *skb)
{
struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
if (!ieee80211_is_data(hdr->frame_control)) {
/* management frames go on AC_VO queue, but are sent
* without QoS control fields */
return 0;
}
if (0 /* injected */) {
/* use AC from radiotap */
}
if (!ieee80211_is_data_qos(hdr->frame_control)) {
skb->priority = 0; /* required for correct WPA/11i MIC */
return ieee802_1d_to_ac[skb->priority];
}
/* use the data classifier to determine what 802.1d tag the
* data frame has */
skb->priority = classify_1d(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];
}
u16 ieee80211_select_queue(struct net_device *dev, struct sk_buff *skb)
{
struct ieee80211_master_priv *mpriv = netdev_priv(dev);
struct ieee80211_local *local = mpriv->local;
struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
u16 queue;
u8 tid;
queue = classify80211(local, skb);
if (unlikely(queue >= local->hw.queues))
queue = local->hw.queues - 1;
/*
* Now we know the 1d priority, fill in the QoS header if
* there is one (and we haven't done this before).
*/
if (!skb->requeue && ieee80211_is_data_qos(hdr->frame_control)) {
u8 *p = ieee80211_get_qos_ctl(hdr);
u8 ack_policy = 0;
tid = skb->priority & IEEE80211_QOS_CTL_TAG1D_MASK;
if (local->wifi_wme_noack_test)
ack_policy |= QOS_CONTROL_ACK_POLICY_NOACK <<
QOS_CONTROL_ACK_POLICY_SHIFT;
/* qos header is 2 bytes, second reserved */
*p++ = ack_policy | tid;
*p = 0;
}
return queue;
}