> The scan code in mac80211 makes the software scan assumption in various
> places. For example, we stop the Tx queue during a software scan so that
> all the Tx packets will be queued by the stack. We also drop frames not
> related to scan in the software scan process. But these are not true for
> hardware scan.
>
> Some wireless hardwares (for example iwl3945/4965) has the ability to
> perform the whole scan process by hardware and/or firmware. The hardware
> scan is relative powerful in that it tries to maintain normal network
> traffic while doing a scan in the background. Some drivers (i.e iwlwifi)
> do provide a way to tune the hardware scan parameters (for example if the
> STA is associated, what's the max time could the STA leave from the
> associated channel, how long the scans get suspended after returning to
> the service channel, etc). But basically this is transparent to the
> stack. mac80211 should not stop Tx queues or drop Rx packets during a
> hardware scan.
>
> This patch resolves the above problem by spliting the current scan
> indicator local->sta_scanning into local->sta_sw_scanning and
> local->sta_hw_scanning. It then changes the scan related code to be aware
> of hardware scan or software scan in various places. With this patch,
> iwlwifi performs much better in the scan-while-associated condition and
> disable_hw_scan=1 should never be required.
>
> Cc: Mohamed Abbas <mohamed.abbas@xxxxxxxxx>
> Cc: Ben Cahill <ben.m.cahill@xxxxxxxxx>
> Signed-off-by: Zhu Yi <yi.zhu@xxxxxxxxx>
Looks good to me.
Acked-by: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>
>
> diff --git a/net/mac80211/ieee80211.c b/net/mac80211/ieee80211.c
> index 59350b8..acbe717 100644
> --- a/net/mac80211/ieee80211.c
> +++ b/net/mac80211/ieee80211.c
> @@ -351,11 +351,14 @@ static int ieee80211_stop(struct net_device *dev)
> synchronize_rcu();
> skb_queue_purge(&sdata->u.sta.skb_queue);
>
> - if (!local->ops->hw_scan &&
> - local->scan_dev == sdata->dev) {
> - local->sta_scanning = 0;
> - cancel_delayed_work(&local->scan_work);
> + if (local->scan_dev == sdata->dev) {
> + if (!local->ops->hw_scan) {
> + local->sta_sw_scanning = 0;
> + cancel_delayed_work(&local->scan_work);
> + } else
> + local->sta_hw_scanning = 0;
> }
> +
> flush_workqueue(local->hw.workqueue);
> /* fall through */
> default:
> @@ -523,7 +526,7 @@ int ieee80211_hw_config(struct ieee80211_local *local)
> struct ieee80211_channel *chan;
> int ret = 0;
>
> - if (local->sta_scanning) {
> + if (local->sta_sw_scanning) {
> chan = local->scan_channel;
> mode = local->scan_hw_mode;
> } else {
> diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
> index 72e1c93..35829b1 100644
> --- a/net/mac80211/ieee80211_i.h
> +++ b/net/mac80211/ieee80211_i.h
> @@ -470,7 +470,8 @@ struct ieee80211_local {
>
> struct list_head interfaces;
>
> - int sta_scanning;
> + bool sta_sw_scanning;
> + bool sta_hw_scanning;
> int scan_channel_idx;
> enum { SCAN_SET_CHANNEL, SCAN_SEND_PROBE } scan_state;
> unsigned long last_scan_completed;
> @@ -749,7 +750,8 @@ int ieee80211_sta_req_scan(struct net_device *dev, u8 *ssid, size_t ssid_len);
> void ieee80211_sta_req_auth(struct net_device *dev,
> struct ieee80211_if_sta *ifsta);
> int ieee80211_sta_scan_results(struct net_device *dev, char *buf, size_t len);
> -void ieee80211_sta_rx_scan(struct net_device *dev, struct sk_buff *skb,
> +ieee80211_txrx_result ieee80211_sta_rx_scan(struct net_device *dev,
> + struct sk_buff *skb,
> struct ieee80211_rx_status *rx_status);
> void ieee80211_rx_bss_list_init(struct net_device *dev);
> void ieee80211_rx_bss_list_deinit(struct net_device *dev);
> diff --git a/net/mac80211/ieee80211_ioctl.c b/net/mac80211/ieee80211_ioctl.c
> index 942b9cc..f2d84f3 100644
> --- a/net/mac80211/ieee80211_ioctl.c
> +++ b/net/mac80211/ieee80211_ioctl.c
> @@ -315,7 +315,7 @@ int ieee80211_set_channel(struct ieee80211_local *local, int channel, int freq)
> }
>
> if (set) {
> - if (local->sta_scanning)
> + if (local->sta_sw_scanning)
> ret = 0;
> else
> ret = ieee80211_hw_config(local);
> @@ -558,8 +558,10 @@ static int ieee80211_ioctl_giwscan(struct net_device *dev,
> {
> int res;
> struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
> - if (local->sta_scanning)
> +
> + if (local->sta_sw_scanning || local->sta_hw_scanning)
> return -EAGAIN;
> +
> res = ieee80211_sta_scan_results(dev, extra, data->length);
> if (res >= 0) {
> data->length = res;
> diff --git a/net/mac80211/ieee80211_sta.c b/net/mac80211/ieee80211_sta.c
> index 015b3f8..26f404a 100644
> --- a/net/mac80211/ieee80211_sta.c
> +++ b/net/mac80211/ieee80211_sta.c
> @@ -1487,8 +1487,18 @@ static void ieee80211_rx_bss_info(struct net_device *dev,
> u32 supp_rates, prev_rates;
> int i, j;
>
> - mode = local->sta_scanning ?
> + mode = local->sta_sw_scanning ?
> local->scan_hw_mode : local->oper_hw_mode;
> +
> + if (local->sta_hw_scanning) {
> + /* search for the correct mode matches the beacon */
> + list_for_each_entry(mode, &local->modes_list, list)
> + if (mode->mode == rx_status->phymode)
> + break;
> +
> + if (mode == NULL)
> + mode = local->oper_hw_mode;
> + }
> rates = mode->rates;
> num_rates = mode->num_rates;
>
> @@ -1871,31 +1881,39 @@ static void ieee80211_sta_rx_queued_mgmt(struct net_device *dev,
> }
>
>
> -void ieee80211_sta_rx_scan(struct net_device *dev, struct sk_buff *skb,
> - struct ieee80211_rx_status *rx_status)
> +ieee80211_txrx_result
> +ieee80211_sta_rx_scan(struct net_device *dev, struct sk_buff *skb,
> + struct ieee80211_rx_status *rx_status)
> {
> struct ieee80211_mgmt *mgmt;
> u16 fc;
>
> - if (skb->len < 24) {
> - dev_kfree_skb(skb);
> - return;
> - }
> + if (skb->len < 2)
> + return TXRX_DROP;
>
> mgmt = (struct ieee80211_mgmt *) skb->data;
> fc = le16_to_cpu(mgmt->frame_control);
>
> + if ((fc & IEEE80211_FCTL_FTYPE) == IEEE80211_FTYPE_CTL)
> + return TXRX_CONTINUE;
> +
> + if (skb->len < 24)
> + return TXRX_DROP;
> +
> if ((fc & IEEE80211_FCTL_FTYPE) == IEEE80211_FTYPE_MGMT) {
> if ((fc & IEEE80211_FCTL_STYPE) == IEEE80211_STYPE_PROBE_RESP) {
> ieee80211_rx_mgmt_probe_resp(dev, mgmt,
> skb->len, rx_status);
> + dev_kfree_skb(skb);
> + return TXRX_QUEUED;
> } else if ((fc & IEEE80211_FCTL_STYPE) == IEEE80211_STYPE_BEACON) {
> ieee80211_rx_mgmt_beacon(dev, mgmt, skb->len,
> rx_status);
> + dev_kfree_skb(skb);
> + return TXRX_QUEUED;
> }
> }
> -
> - dev_kfree_skb(skb);
> + return TXRX_CONTINUE;
> }
>
>
> @@ -1985,7 +2003,7 @@ void ieee80211_sta_work(struct work_struct *work)
> if (!netif_running(dev))
> return;
>
> - if (local->sta_scanning)
> + if (local->sta_sw_scanning || local->sta_hw_scanning)
> return;
>
> if (sdata->type != IEEE80211_IF_TYPE_STA &&
> @@ -2643,9 +2661,15 @@ void ieee80211_scan_completed(struct ieee80211_hw *hw)
> union iwreq_data wrqu;
>
> local->last_scan_completed = jiffies;
> - wmb();
> - local->sta_scanning = 0;
> + memset(&wrqu, 0, sizeof(wrqu));
> + wireless_send_event(dev, SIOCGIWSCAN, &wrqu, NULL);
>
> + if (local->sta_hw_scanning) {
> + local->sta_hw_scanning = 0;
> + goto done;
> + }
> +
> + local->sta_sw_scanning = 0;
> if (ieee80211_hw_config(local))
> printk(KERN_DEBUG "%s: failed to restore operational"
> "channel after scan\n", dev->name);
> @@ -2661,9 +2685,6 @@ void ieee80211_scan_completed(struct ieee80211_hw *hw)
>
> netif_tx_unlock_bh(local->mdev);
>
> - memset(&wrqu, 0, sizeof(wrqu));
> - wireless_send_event(dev, SIOCGIWSCAN, &wrqu, NULL);
> -
> rcu_read_lock();
> list_for_each_entry_rcu(sdata, &local->interfaces, list) {
>
> @@ -2681,6 +2702,7 @@ void ieee80211_scan_completed(struct ieee80211_hw *hw)
> }
> rcu_read_unlock();
>
> +done:
> sdata = IEEE80211_DEV_TO_SUB_IF(dev);
> if (sdata->type == IEEE80211_IF_TYPE_IBSS) {
> struct ieee80211_if_sta *ifsta = &sdata->u.sta;
> @@ -2703,7 +2725,7 @@ void ieee80211_sta_scan_work(struct work_struct *work)
> int skip;
> unsigned long next_delay = 0;
>
> - if (!local->sta_scanning)
> + if (!local->sta_sw_scanning)
> return;
>
> switch (local->scan_state) {
> @@ -2766,7 +2788,7 @@ void ieee80211_sta_scan_work(struct work_struct *work)
> break;
> }
>
> - if (local->sta_scanning)
> + if (local->sta_sw_scanning)
> queue_delayed_work(local->hw.workqueue, &local->scan_work,
> next_delay);
> }
> @@ -2798,7 +2820,7 @@ static int ieee80211_sta_start_scan(struct net_device *dev,
> * ResultCode: SUCCESS, INVALID_PARAMETERS
> */
>
> - if (local->sta_scanning) {
> + if (local->sta_sw_scanning || local->sta_hw_scanning) {
> if (local->scan_dev == dev)
> return 0;
> return -EBUSY;
> @@ -2806,15 +2828,15 @@ static int ieee80211_sta_start_scan(struct net_device *dev,
>
> if (local->ops->hw_scan) {
> int rc = local->ops->hw_scan(local_to_hw(local),
> - ssid, ssid_len);
> + ssid, ssid_len);
> if (!rc) {
> - local->sta_scanning = 1;
> + local->sta_hw_scanning = 1;
> local->scan_dev = dev;
> }
> return rc;
> }
>
> - local->sta_scanning = 1;
> + local->sta_sw_scanning = 1;
>
> rcu_read_lock();
> list_for_each_entry_rcu(sdata, &local->interfaces, list) {
> @@ -2869,7 +2891,7 @@ int ieee80211_sta_req_scan(struct net_device *dev, u8 *ssid, size_t ssid_len)
> if (sdata->type != IEEE80211_IF_TYPE_STA)
> return ieee80211_sta_start_scan(dev, ssid, ssid_len);
>
> - if (local->sta_scanning) {
> + if (local->sta_sw_scanning || local->sta_hw_scanning) {
> if (local->scan_dev == dev)
> return 0;
> return -EBUSY;
> diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
> index 428a9fc..596ff71 100644
> --- a/net/mac80211/rx.c
> +++ b/net/mac80211/rx.c
> @@ -338,8 +338,14 @@ ieee80211_rx_h_passive_scan(struct ieee80211_txrx_data *rx)
> struct ieee80211_local *local = rx->local;
> struct sk_buff *skb = rx->skb;
>
> - if (unlikely(local->sta_scanning != 0)) {
> - ieee80211_sta_rx_scan(rx->dev, skb, rx->u.rx.status);
> + if (unlikely(local->sta_hw_scanning))
> + return ieee80211_sta_rx_scan(rx->dev, skb, rx->u.rx.status);
> +
> + if (unlikely(local->sta_sw_scanning)) {
> + /* drop all the other packets during a software scan anyway */
> + if (ieee80211_sta_rx_scan(rx->dev, skb, rx->u.rx.status)
> + != TXRX_QUEUED)
> + dev_kfree_skb(skb);
> return TXRX_QUEUED;
> }
>
> @@ -1486,7 +1492,7 @@ void __ieee80211_rx(struct ieee80211_hw *hw, struct sk_buff *skb,
> goto end;
> }
>
> - if (unlikely(local->sta_scanning))
> + if (unlikely(local->sta_sw_scanning || local->sta_hw_scanning))
> rx.flags |= IEEE80211_TXRXD_RXIN_SCAN;
>
> if (__ieee80211_invoke_rx_handlers(local, local->rx_pre_handlers, &rx,
> diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
> index 1a53154..a6a657f 100644
> --- a/net/mac80211/tx.c
> +++ b/net/mac80211/tx.c
> @@ -225,7 +225,7 @@ ieee80211_tx_h_check_assoc(struct ieee80211_txrx_data *tx)
> if (unlikely(tx->flags & IEEE80211_TXRXD_TX_INJECTED))
> return TXRX_CONTINUE;
>
> - if (unlikely(tx->local->sta_scanning != 0) &&
> + if (unlikely(tx->local->sta_sw_scanning) &&
> ((tx->fc & IEEE80211_FCTL_FTYPE) != IEEE80211_FTYPE_MGMT ||
> (tx->fc & IEEE80211_FCTL_STYPE) != IEEE80211_STYPE_PROBE_REQ))
> return TXRX_DROP;
> -
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