From 142b9f5074dc0d09dc0025739ad437723d7bf527 Mon Sep 17 00:00:00 2001 From: Helmut Schaa Date: Thu, 23 Jul 2009 13:18:01 +0200 Subject: [PATCH] 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 Signed-off-by: John W. Linville --- net/mac80211/ieee80211_i.h | 36 +++++++++++- net/mac80211/rx.c | 6 +- net/mac80211/scan.c | 117 ++++++++++++++++++++++++++++++++++--- net/mac80211/tx.c | 2 +- 4 files changed, 148 insertions(+), 13 deletions(-) diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h index 783a125402b0..efda19ee0152 100644 --- a/net/mac80211/ieee80211_i.h +++ b/net/mac80211/ieee80211_i.h @@ -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; diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c index 9c1679d124ba..cb95a3116034 100644 --- a/net/mac80211/rx.c +++ b/net/mac80211/rx.c @@ -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); diff --git a/net/mac80211/scan.c b/net/mac80211/scan.c index 4233c3d700ce..d56b9da8b28a 100644 --- a/net/mac80211/scan.c +++ b/net/mac80211/scan.c @@ -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; } + /* 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; - local->scan_state = SCAN_SET_CHANNEL; 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); diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c index d7491dc2a65c..70ff4f065665 100644 --- a/net/mac80211/tx.c +++ b/net/mac80211/tx.c @@ -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)) /* -- 2.39.5