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mac80211: implement basic background scanning 

Introduce a new scan flag "SCAN_OFF_CHANNEL" which basically tells us
that we are currently on a different channel for scanning and cannot
RX/TX. "SCAN_SW_SCANNING" tells us that we are currently running a
software scan but we might as well be on the operating channel to RX/TX.
While "SCAN_SW_SCANNING" is set during the whole scan "SCAN_OFF_CHANNEL"
is set when leaving the operating channel and unset when coming back.

Introduce two new scan states "SCAN_LEAVE_OPER_CHANNEL" and
"SCAN_ENTER_OPER_CHANNEL" which basically implement the functionality we
need to leave the operating channel (send a nullfunc to the AP and stop
the queues) and enter it again (send a nullfunc to the AP and start the
queues again).

Enhance the scan state "SCAN_DECISION" to switch back to the operating
channel after each scanned channel. In the future it sould be simple
to enhance the decision state to scan as much channels in a row as the
qos latency allows us.

Signed-off-by: Helmut Schaa <helmut.schaa@googlemail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
This commit is contained in:
Helmut Schaa 2009-07-23 13:18:01 +02:00 committed by John W. Linville
parent fbe9c429f1
commit 142b9f5074
4 changed files with 148 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

36
net/mac80211/ieee80211_i.h
View File

@ -570,9 +570,41 @@ enum queue_stop_reason {
IEEE80211_QUEUE_STOP_REASON_SKB_ADD,
};
/**
* mac80211 scan flags - currently active scan mode
*
* @SCAN_SW_SCANNING: We're currently in the process of scanning but may as
* well be on the operating channel
* @SCAN_HW_SCANNING: The hardware is scanning for us, we have no way to
* determine if we are on the operating channel or not
* @SCAN_OFF_CHANNEL: We're off our operating channel for scanning,
* gets only set in conjunction with SCAN_SW_SCANNING
*/
enum {
SCAN_SW_SCANNING,
SCAN_HW_SCANNING
SCAN_HW_SCANNING,
SCAN_OFF_CHANNEL,
};
/**
* enum mac80211_scan_state - scan state machine states
*
* @SCAN_DECISION: Main entry point to the scan state machine, this state
* determines if we should keep on scanning or switch back to the
* operating channel
* @SCAN_SET_CHANNEL: Set the next channel to be scanned
* @SCAN_SEND_PROBE: Send probe requests and wait for probe responses
* @SCAN_LEAVE_OPER_CHANNEL: Leave the operating channel, notify the AP
* about us leaving the channel and stop all associated STA interfaces
* @SCAN_ENTER_OPER_CHANNEL: Enter the operating channel again, notify the
* AP about us being back and restart all associated STA interfaces
*/
enum mac80211_scan_state {
SCAN_DECISION,
SCAN_SET_CHANNEL,
SCAN_SEND_PROBE,
SCAN_LEAVE_OPER_CHANNEL,
SCAN_ENTER_OPER_CHANNEL,
};
struct ieee80211_local {
@ -683,7 +715,7 @@ struct ieee80211_local {
int scan_channel_idx;
int scan_ies_len;
enum { SCAN_DECISION, SCAN_SET_CHANNEL, SCAN_SEND_PROBE } scan_state;
enum mac80211_scan_state scan_state;
struct delayed_work scan_work;
struct ieee80211_sub_if_data *scan_sdata;
enum nl80211_channel_type oper_channel_type;

6
net/mac80211/rx.c
View File

@ -421,7 +421,8 @@ ieee80211_rx_h_passive_scan(struct ieee80211_rx_data *rx)
if (unlikely(test_bit(SCAN_HW_SCANNING, &local->scanning)))
return ieee80211_scan_rx(rx->sdata, skb);
if (unlikely(test_bit(SCAN_SW_SCANNING, &local->scanning))) {
if (unlikely(test_bit(SCAN_SW_SCANNING, &local->scanning) &&
(rx->flags & IEEE80211_RX_IN_SCAN))) {
/* drop all the other packets during a software scan anyway */
if (ieee80211_scan_rx(rx->sdata, skb) != RX_QUEUED)
dev_kfree_skb(skb);
@ -2136,7 +2137,8 @@ static void __ieee80211_rx_handle_packet(struct ieee80211_hw *hw,
return;
}
if (unlikely(local->scanning))
if (unlikely(test_bit(SCAN_HW_SCANNING, &local->scanning) ||
test_bit(SCAN_OFF_CHANNEL, &local->scanning)))
rx.flags |= IEEE80211_RX_IN_SCAN;
ieee80211_parse_qos(&rx);

117
net/mac80211/scan.c
View File

@ -365,12 +365,11 @@ static int ieee80211_start_sw_scan(struct ieee80211_local *local)
ieee80211_bss_info_change_notify(
sdata, BSS_CHANGED_BEACON_ENABLED);
if (sdata->vif.type == NL80211_IFTYPE_STATION) {
if (sdata->u.mgd.associated) {
netif_tx_stop_all_queues(sdata->dev);
ieee80211_scan_ps_enable(sdata);
}
} else
/*
* only handle non-STA interfaces here, STA interfaces
* are handled in the scan state machine
*/
if (sdata->vif.type != NL80211_IFTYPE_STATION)
netif_tx_stop_all_queues(sdata->dev);
}
mutex_unlock(&local->iflist_mtx);
@ -474,17 +473,113 @@ static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
static int ieee80211_scan_state_decision(struct ieee80211_local *local,
unsigned long *next_delay)
{
/* if no more bands/channels left, complete scan */
bool associated = false;
struct ieee80211_sub_if_data *sdata;
/* if no more bands/channels left, complete scan and advance to the idle state */
if (local->scan_channel_idx >= local->scan_req->n_channels) {
ieee80211_scan_completed(&local->hw, false);
return 1;
}
*next_delay = 0;
/* check if at least one STA interface is associated */
mutex_lock(&local->iflist_mtx);
list_for_each_entry(sdata, &local->interfaces, list) {
if (!netif_running(sdata->dev))
continue;
if (sdata->vif.type == NL80211_IFTYPE_STATION) {
if (sdata->u.mgd.associated) {
associated = true;
break;
}
}
}
mutex_unlock(&local->iflist_mtx);
if (local->scan_channel) {
/*
* we're currently scanning a different channel, let's
* switch back to the operating channel now if at least
* one interface is associated. Otherwise just scan the
* next channel
*/
if (associated)
local->scan_state = SCAN_ENTER_OPER_CHANNEL;
else
local->scan_state = SCAN_SET_CHANNEL;
} else {
/*
* we're on the operating channel currently, let's
* leave that channel now to scan another one
*/
local->scan_state = SCAN_LEAVE_OPER_CHANNEL;
}
*next_delay = 0;
return 0;
}
static void ieee80211_scan_state_leave_oper_channel(struct ieee80211_local *local,
unsigned long *next_delay)
{
struct ieee80211_sub_if_data *sdata;
/*
* notify the AP about us leaving the channel and stop all STA interfaces
*/
mutex_lock(&local->iflist_mtx);
list_for_each_entry(sdata, &local->interfaces, list) {
if (!netif_running(sdata->dev))
continue;
if (sdata->vif.type == NL80211_IFTYPE_STATION) {
netif_tx_stop_all_queues(sdata->dev);
if (sdata->u.mgd.associated)
ieee80211_scan_ps_enable(sdata);
}
}
mutex_unlock(&local->iflist_mtx);
__set_bit(SCAN_OFF_CHANNEL, &local->scanning);
/* advance to the next channel to be scanned */
*next_delay = HZ / 10;
local->scan_state = SCAN_SET_CHANNEL;
}
static void ieee80211_scan_state_enter_oper_channel(struct ieee80211_local *local,
unsigned long *next_delay)
{
struct ieee80211_sub_if_data *sdata = local->scan_sdata;
/* switch back to the operating channel */
local->scan_channel = NULL;
ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
/*
* notify the AP about us being back and restart all STA interfaces
*/
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.associated)
ieee80211_scan_ps_disable(sdata);
netif_tx_wake_all_queues(sdata->dev);
}
}
mutex_unlock(&local->iflist_mtx);
__clear_bit(SCAN_OFF_CHANNEL, &local->scanning);
*next_delay = HZ / 5;
local->scan_state = SCAN_DECISION;
}
static void ieee80211_scan_state_set_channel(struct ieee80211_local *local,
unsigned long *next_delay)
{
@ -609,6 +704,12 @@ void ieee80211_scan_work(struct work_struct *work)
case SCAN_SEND_PROBE:
ieee80211_scan_state_send_probe(local, &next_delay);
break;
case SCAN_LEAVE_OPER_CHANNEL:
ieee80211_scan_state_leave_oper_channel(local, &next_delay);
break;
case SCAN_ENTER_OPER_CHANNEL:
ieee80211_scan_state_enter_oper_channel(local, &next_delay);
break;
}
} while (next_delay == 0);

2
net/mac80211/tx.c
View File

@ -192,7 +192,7 @@ ieee80211_tx_h_check_assoc(struct ieee80211_tx_data *tx)
if (unlikely(info->flags & IEEE80211_TX_CTL_INJECTED))
return TX_CONTINUE;
if (unlikely(test_bit(SCAN_SW_SCANNING, &tx->local->scanning)) &&
if (unlikely(test_bit(SCAN_OFF_CHANNEL, &tx->local->scanning)) &&
!ieee80211_is_probe_req(hdr->frame_control) &&
!ieee80211_is_nullfunc(hdr->frame_control))
/*