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linux/net/mac80211/scan.c
Johannes Berg 5cff20e6c5 mac80211: tell driver when idle
When we aren't doing anything in mac80211, we can turn off
much of the hardware, depending on the driver/hw. Not doing
anything, aka being idle, means:

 * no monitor interfaces
 * no AP/mesh/wds interfaces
 * any station interfaces are in DISABLED state
 * any IBSS interfaces aren't trying to be in a network
 * we aren't trying to scan

By creating a new function that verifies these conditions and calling
it at strategic points where the states of those conditions change,
we can easily make mac80211 tell the driver when we are idle to save
power.

Additionally, this fixes a small quirk where a recalculated powersave
state is passed to the driver even if the hardware is about to stopped
completely.

This patch intentionally doesn't touch radio_enabled because that is
currently implemented to be a soft rfkill which is inappropriate here
when we need to be able to wake up with low latency.

One thing I'm not entirely sure about is this:

  phy0: device no longer idle - in use
  wlan0: direct probe to AP 00:11:24:91:07:4d try 1
  wlan0 direct probe responded
  wlan0: authenticate with AP 00:11:24:91:07:4d
  wlan0: authenticated
> phy0: device now idle
> phy0: device no longer idle - in use
  wlan0: associate with AP 00:11:24:91:07:4d
  wlan0: RX AssocResp from 00:11:24:91:07:4d (capab=0x401 status=0 aid=1)
  wlan0: associated

Is it appropriate to go into idle state for a short time when we have
just authenticated, but not associated yet? This happens only with the
userspace SME, because we cannot really know how long it will wait
before asking us to associate. Would going idle after a short timeout
be more appropriate? We may need to revisit this, depending on what
happens.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
2009-05-06 15:14:51 -04:00

618 lines
16 KiB
C

/*
* Scanning implementation
*
* Copyright 2003, Jouni Malinen <jkmaline@cc.hut.fi>
* Copyright 2004, Instant802 Networks, Inc.
* Copyright 2005, Devicescape Software, Inc.
* Copyright 2006-2007 Jiri Benc <jbenc@suse.cz>
* Copyright 2007, Michael Wu <flamingice@sourmilk.net>
*
* 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.
*/
/* TODO: figure out how to avoid that the "current BSS" expires */
#include <linux/wireless.h>
#include <linux/if_arp.h>
#include <linux/rtnetlink.h>
#include <net/mac80211.h>
#include <net/iw_handler.h>
#include "ieee80211_i.h"
#include "driver-ops.h"
#include "mesh.h"
#define IEEE80211_PROBE_DELAY (HZ / 33)
#define IEEE80211_CHANNEL_TIME (HZ / 33)
#define IEEE80211_PASSIVE_CHANNEL_TIME (HZ / 5)
struct ieee80211_bss *
ieee80211_rx_bss_get(struct ieee80211_local *local, u8 *bssid, int freq,
u8 *ssid, u8 ssid_len)
{
return (void *)cfg80211_get_bss(local->hw.wiphy,
ieee80211_get_channel(local->hw.wiphy,
freq),
bssid, ssid, ssid_len,
0, 0);
}
static void ieee80211_rx_bss_free(struct cfg80211_bss *cbss)
{
struct ieee80211_bss *bss = (void *)cbss;
kfree(bss_mesh_id(bss));
kfree(bss_mesh_cfg(bss));
}
void ieee80211_rx_bss_put(struct ieee80211_local *local,
struct ieee80211_bss *bss)
{
cfg80211_put_bss((struct cfg80211_bss *)bss);
}
struct ieee80211_bss *
ieee80211_bss_info_update(struct ieee80211_local *local,
struct ieee80211_rx_status *rx_status,
struct ieee80211_mgmt *mgmt,
size_t len,
struct ieee802_11_elems *elems,
struct ieee80211_channel *channel,
bool beacon)
{
struct ieee80211_bss *bss;
int clen;
s32 signal = 0;
if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM)
signal = rx_status->signal * 100;
else if (local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC)
signal = (rx_status->signal * 100) / local->hw.max_signal;
bss = (void *)cfg80211_inform_bss_frame(local->hw.wiphy, channel,
mgmt, len, signal, GFP_ATOMIC);
if (!bss)
return NULL;
bss->cbss.free_priv = ieee80211_rx_bss_free;
/* save the ERP value so that it is available at association time */
if (elems->erp_info && elems->erp_info_len >= 1) {
bss->erp_value = elems->erp_info[0];
bss->has_erp_value = 1;
}
if (elems->tim) {
struct ieee80211_tim_ie *tim_ie =
(struct ieee80211_tim_ie *)elems->tim;
bss->dtim_period = tim_ie->dtim_period;
}
/* set default value for buggy APs */
if (!elems->tim || bss->dtim_period == 0)
bss->dtim_period = 1;
bss->supp_rates_len = 0;
if (elems->supp_rates) {
clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
if (clen > elems->supp_rates_len)
clen = elems->supp_rates_len;
memcpy(&bss->supp_rates[bss->supp_rates_len], elems->supp_rates,
clen);
bss->supp_rates_len += clen;
}
if (elems->ext_supp_rates) {
clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
if (clen > elems->ext_supp_rates_len)
clen = elems->ext_supp_rates_len;
memcpy(&bss->supp_rates[bss->supp_rates_len],
elems->ext_supp_rates, clen);
bss->supp_rates_len += clen;
}
bss->wmm_used = elems->wmm_param || elems->wmm_info;
if (!beacon)
bss->last_probe_resp = jiffies;
return bss;
}
void ieee80211_rx_bss_remove(struct ieee80211_sub_if_data *sdata, u8 *bssid,
int freq, u8 *ssid, u8 ssid_len)
{
struct ieee80211_bss *bss;
struct ieee80211_local *local = sdata->local;
bss = ieee80211_rx_bss_get(local, bssid, freq, ssid, ssid_len);
if (bss) {
cfg80211_unlink_bss(local->hw.wiphy, (void *)bss);
ieee80211_rx_bss_put(local, bss);
}
}
ieee80211_rx_result
ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb,
struct ieee80211_rx_status *rx_status)
{
struct ieee80211_mgmt *mgmt;
struct ieee80211_bss *bss;
u8 *elements;
struct ieee80211_channel *channel;
size_t baselen;
int freq;
__le16 fc;
bool presp, beacon = false;
struct ieee802_11_elems elems;
if (skb->len < 2)
return RX_DROP_UNUSABLE;
mgmt = (struct ieee80211_mgmt *) skb->data;
fc = mgmt->frame_control;
if (ieee80211_is_ctl(fc))
return RX_CONTINUE;
if (skb->len < 24)
return RX_DROP_MONITOR;
presp = ieee80211_is_probe_resp(fc);
if (presp) {
/* ignore ProbeResp to foreign address */
if (memcmp(mgmt->da, sdata->dev->dev_addr, ETH_ALEN))
return RX_DROP_MONITOR;
presp = true;
elements = mgmt->u.probe_resp.variable;
baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
} else {
beacon = ieee80211_is_beacon(fc);
baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
elements = mgmt->u.beacon.variable;
}
if (!presp && !beacon)
return RX_CONTINUE;
if (baselen > skb->len)
return RX_DROP_MONITOR;
ieee802_11_parse_elems(elements, skb->len - baselen, &elems);
if (elems.ds_params && elems.ds_params_len == 1)
freq = ieee80211_channel_to_frequency(elems.ds_params[0]);
else
freq = rx_status->freq;
channel = ieee80211_get_channel(sdata->local->hw.wiphy, freq);
if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
return RX_DROP_MONITOR;
bss = ieee80211_bss_info_update(sdata->local, rx_status,
mgmt, skb->len, &elems,
channel, beacon);
if (bss)
ieee80211_rx_bss_put(sdata->local, bss);
dev_kfree_skb(skb);
return RX_QUEUED;
}
/*
* inform AP that we will go to sleep so that it will buffer the frames
* while we scan
*/
static void ieee80211_scan_ps_enable(struct ieee80211_sub_if_data *sdata)
{
struct ieee80211_local *local = sdata->local;
bool ps = false;
/* FIXME: what to do when local->pspolling is true? */
del_timer_sync(&local->dynamic_ps_timer);
cancel_work_sync(&local->dynamic_ps_enable_work);
if (local->hw.conf.flags & IEEE80211_CONF_PS) {
ps = true;
local->hw.conf.flags &= ~IEEE80211_CONF_PS;
ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
}
if (!ps || !(local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK))
/*
* If power save was enabled, no need to send a nullfunc
* frame because AP knows that we are sleeping. But if the
* hardware is creating the nullfunc frame for power save
* status (ie. IEEE80211_HW_PS_NULLFUNC_STACK is not
* enabled) and power save was enabled, the firmware just
* sent a null frame with power save disabled. So we need
* to send a new nullfunc frame to inform the AP that we
* are again sleeping.
*/
ieee80211_send_nullfunc(local, sdata, 1);
}
/* inform AP that we are awake again, unless power save is enabled */
static void ieee80211_scan_ps_disable(struct ieee80211_sub_if_data *sdata)
{
struct ieee80211_local *local = sdata->local;
if (!local->ps_sdata)
ieee80211_send_nullfunc(local, sdata, 0);
else {
/*
* In !IEEE80211_HW_PS_NULLFUNC_STACK case the hardware
* will send a nullfunc frame with the powersave bit set
* even though the AP already knows that we are sleeping.
* This could be avoided by sending a null frame with power
* save bit disabled before enabling the power save, but
* this doesn't gain anything.
*
* When IEEE80211_HW_PS_NULLFUNC_STACK is enabled, no need
* to send a nullfunc frame because AP already knows that
* we are sleeping, let's just enable power save mode in
* hardware.
*/
local->hw.conf.flags |= IEEE80211_CONF_PS;
ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
}
}
static void ieee80211_restore_scan_ies(struct ieee80211_local *local)
{
kfree(local->scan_req->ie);
local->scan_req->ie = local->orig_ies;
local->scan_req->ie_len = local->orig_ies_len;
}
void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
{
struct ieee80211_local *local = hw_to_local(hw);
struct ieee80211_sub_if_data *sdata;
bool was_hw_scan;
mutex_lock(&local->scan_mtx);
if (WARN_ON(!local->hw_scanning && !local->sw_scanning)) {
mutex_unlock(&local->scan_mtx);
return;
}
if (WARN_ON(!local->scan_req)) {
mutex_unlock(&local->scan_mtx);
return;
}
if (local->hw_scanning)
ieee80211_restore_scan_ies(local);
if (local->scan_req != &local->int_scan_req)
cfg80211_scan_done(local->scan_req, aborted);
local->scan_req = NULL;
was_hw_scan = local->hw_scanning;
local->hw_scanning = false;
local->sw_scanning = false;
/* we only have to protect scan_req and hw/sw scan */
mutex_unlock(&local->scan_mtx);
ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
if (was_hw_scan)
goto done;
netif_tx_lock_bh(local->mdev);
netif_addr_lock(local->mdev);
local->filter_flags &= ~FIF_BCN_PRBRESP_PROMISC;
drv_configure_filter(local, FIF_BCN_PRBRESP_PROMISC,
&local->filter_flags,
local->mdev->mc_count,
local->mdev->mc_list);
netif_addr_unlock(local->mdev);
netif_tx_unlock_bh(local->mdev);
drv_sw_scan_complete(local);
mutex_lock(&local->iflist_mtx);
list_for_each_entry(sdata, &local->interfaces, list) {
if (!netif_running(sdata->dev))
continue;
/* Tell AP we're back */
if (sdata->vif.type == NL80211_IFTYPE_STATION) {
if (sdata->u.mgd.flags & IEEE80211_STA_ASSOCIATED) {
ieee80211_scan_ps_disable(sdata);
netif_tx_wake_all_queues(sdata->dev);
}
} else
netif_tx_wake_all_queues(sdata->dev);
/* re-enable beaconing */
if (sdata->vif.type == NL80211_IFTYPE_AP ||
sdata->vif.type == NL80211_IFTYPE_ADHOC ||
sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
ieee80211_bss_info_change_notify(
sdata, BSS_CHANGED_BEACON_ENABLED);
}
mutex_unlock(&local->iflist_mtx);
done:
ieee80211_recalc_idle(local);
ieee80211_mlme_notify_scan_completed(local);
ieee80211_ibss_notify_scan_completed(local);
ieee80211_mesh_notify_scan_completed(local);
}
EXPORT_SYMBOL(ieee80211_scan_completed);
static int ieee80211_start_sw_scan(struct ieee80211_local *local)
{
struct ieee80211_sub_if_data *sdata;
/*
* Hardware/driver doesn't support hw_scan, so use software
* scanning instead. First send a nullfunc frame with power save
* bit on so that AP will buffer the frames for us while we are not
* listening, then send probe requests to each channel and wait for
* the responses. After all channels are scanned, tune back to the
* original channel and send a nullfunc frame with power save bit
* off to trigger the AP to send us all the buffered frames.
*
* Note that while local->sw_scanning is true everything else but
* nullfunc frames and probe requests will be dropped in
* ieee80211_tx_h_check_assoc().
*/
drv_sw_scan_start(local);
mutex_lock(&local->iflist_mtx);
list_for_each_entry(sdata, &local->interfaces, list) {
if (!netif_running(sdata->dev))
continue;
/* disable beaconing */
if (sdata->vif.type == NL80211_IFTYPE_AP ||
sdata->vif.type == NL80211_IFTYPE_ADHOC ||
sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
ieee80211_bss_info_change_notify(
sdata, BSS_CHANGED_BEACON_ENABLED);
if (sdata->vif.type == NL80211_IFTYPE_STATION) {
if (sdata->u.mgd.flags & IEEE80211_STA_ASSOCIATED) {
netif_tx_stop_all_queues(sdata->dev);
ieee80211_scan_ps_enable(sdata);
}
} else
netif_tx_stop_all_queues(sdata->dev);
}
mutex_unlock(&local->iflist_mtx);
local->scan_state = SCAN_SET_CHANNEL;
local->scan_channel_idx = 0;
netif_addr_lock_bh(local->mdev);
local->filter_flags |= FIF_BCN_PRBRESP_PROMISC;
drv_configure_filter(local, FIF_BCN_PRBRESP_PROMISC,
&local->filter_flags,
local->mdev->mc_count,
local->mdev->mc_list);
netif_addr_unlock_bh(local->mdev);
/* TODO: start scan as soon as all nullfunc frames are ACKed */
queue_delayed_work(local->hw.workqueue, &local->scan_work,
IEEE80211_CHANNEL_TIME);
return 0;
}
static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
struct cfg80211_scan_request *req)
{
struct ieee80211_local *local = sdata->local;
struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
int rc;
if (local->scan_req)
return -EBUSY;
if (local->ops->hw_scan) {
u8 *ies;
int ielen;
ies = kmalloc(2 + IEEE80211_MAX_SSID_LEN +
local->scan_ies_len + req->ie_len, GFP_KERNEL);
if (!ies)
return -ENOMEM;
ielen = ieee80211_build_preq_ies(local, ies,
req->ie, req->ie_len);
local->orig_ies = req->ie;
local->orig_ies_len = req->ie_len;
req->ie = ies;
req->ie_len = ielen;
}
local->scan_req = req;
local->scan_sdata = sdata;
if (req != &local->int_scan_req &&
sdata->vif.type == NL80211_IFTYPE_STATION &&
(ifmgd->state == IEEE80211_STA_MLME_DIRECT_PROBE ||
ifmgd->state == IEEE80211_STA_MLME_AUTHENTICATE ||
ifmgd->state == IEEE80211_STA_MLME_ASSOCIATE)) {
/* actually wait for the assoc to finish/time out */
set_bit(IEEE80211_STA_REQ_SCAN, &ifmgd->request);
return 0;
}
if (local->ops->hw_scan)
local->hw_scanning = true;
else
local->sw_scanning = true;
/*
* Kicking off the scan need not be protected,
* only the scan variable stuff, since now
* local->scan_req is assigned and other callers
* will abort their scan attempts.
*
* This avoids getting a scan_mtx -> iflist_mtx
* dependency, so that the scan completed calls
* have more locking freedom.
*/
ieee80211_recalc_idle(local);
mutex_unlock(&local->scan_mtx);
if (local->ops->hw_scan)
rc = drv_hw_scan(local, local->scan_req);
else
rc = ieee80211_start_sw_scan(local);
mutex_lock(&local->scan_mtx);
if (rc) {
if (local->ops->hw_scan) {
local->hw_scanning = false;
ieee80211_restore_scan_ies(local);
} else
local->sw_scanning = false;
ieee80211_recalc_idle(local);
local->scan_req = NULL;
local->scan_sdata = NULL;
}
return rc;
}
void ieee80211_scan_work(struct work_struct *work)
{
struct ieee80211_local *local =
container_of(work, struct ieee80211_local, scan_work.work);
struct ieee80211_sub_if_data *sdata = local->scan_sdata;
struct ieee80211_channel *chan;
int skip, i;
unsigned long next_delay = 0;
mutex_lock(&local->scan_mtx);
if (!sdata || !local->scan_req) {
mutex_unlock(&local->scan_mtx);
return;
}
if (local->scan_req && !(local->sw_scanning || local->hw_scanning)) {
struct cfg80211_scan_request *req = local->scan_req;
int rc;
local->scan_req = NULL;
rc = __ieee80211_start_scan(sdata, req);
mutex_unlock(&local->scan_mtx);
if (rc)
ieee80211_scan_completed(&local->hw, true);
return;
}
mutex_unlock(&local->scan_mtx);
/*
* Avoid re-scheduling when the sdata is going away.
*/
if (!netif_running(sdata->dev)) {
ieee80211_scan_completed(&local->hw, true);
return;
}
switch (local->scan_state) {
case SCAN_SET_CHANNEL:
/* if no more bands/channels left, complete scan */
if (local->scan_channel_idx >= local->scan_req->n_channels) {
ieee80211_scan_completed(&local->hw, false);
return;
}
skip = 0;
chan = local->scan_req->channels[local->scan_channel_idx];
if (chan->flags & IEEE80211_CHAN_DISABLED ||
(sdata->vif.type == NL80211_IFTYPE_ADHOC &&
chan->flags & IEEE80211_CHAN_NO_IBSS))
skip = 1;
if (!skip) {
local->scan_channel = chan;
if (ieee80211_hw_config(local,
IEEE80211_CONF_CHANGE_CHANNEL))
skip = 1;
}
/* advance state machine to next channel/band */
local->scan_channel_idx++;
if (skip)
break;
next_delay = IEEE80211_PROBE_DELAY +
usecs_to_jiffies(local->hw.channel_change_time);
local->scan_state = SCAN_SEND_PROBE;
break;
case SCAN_SEND_PROBE:
next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
local->scan_state = SCAN_SET_CHANNEL;
if (local->scan_channel->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
!local->scan_req->n_ssids)
break;
for (i = 0; i < local->scan_req->n_ssids; i++)
ieee80211_send_probe_req(
sdata, NULL,
local->scan_req->ssids[i].ssid,
local->scan_req->ssids[i].ssid_len,
local->scan_req->ie, local->scan_req->ie_len);
next_delay = IEEE80211_CHANNEL_TIME;
break;
}
queue_delayed_work(local->hw.workqueue, &local->scan_work,
next_delay);
}
int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
struct cfg80211_scan_request *req)
{
int res;
mutex_lock(&sdata->local->scan_mtx);
res = __ieee80211_start_scan(sdata, req);
mutex_unlock(&sdata->local->scan_mtx);
return res;
}
int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata,
const u8 *ssid, u8 ssid_len)
{
struct ieee80211_local *local = sdata->local;
int ret = -EBUSY;
mutex_lock(&local->scan_mtx);
/* busy scanning */
if (local->scan_req)
goto unlock;
memcpy(local->int_scan_req.ssids[0].ssid, ssid, IEEE80211_MAX_SSID_LEN);
local->int_scan_req.ssids[0].ssid_len = ssid_len;
ret = __ieee80211_start_scan(sdata, &sdata->local->int_scan_req);
unlock:
mutex_unlock(&local->scan_mtx);
return ret;
}