On Tue, 2008-12-09 at 16:57 +0200, Jouni Malinen wrote:
> AP mode operations are seriously affected if mac80211 runs through a
> multi-second scan while the AP is trying to send Beacon frames on the
> operation channel. While this could be implemented in a way that does
> not cause too many problems, it is not very simple and will require
> synchronization with Beacon frame scheduling in the drivers (scan one
> channel at a time between Beacon frames). Furthermore, such scanning
> takes quite a bit longer time and existing userspace applications
> would be likely to timeout while waiting for the results.
>
> For now, just refuse requests for new scans (SIOCSIWSCAN) when in AP
> mode. In practice, this moves the rejection from iwl* drivers into
> mac80211 to make it apply to every mac80211-based driver.
>
> This issue shows up in associated stations getting disconnected when
> something (e.g., Network Manager) requests a scan while the interface
> is in AP mode. When doing this continuously (e.g., NM does it every 60
> seconds), the network gets close to useless.
>
> Signed-off-by: Jouni Malinen <jouni.malinen@xxxxxxxxxxx>
Acked-by: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>
>
> Index: wireless-testing/drivers/net/wireless/iwlwifi/iwl-agn.c
> ===================================================================
> --- wireless-testing.orig/drivers/net/wireless/iwlwifi/iwl-agn.c 2008-12-09 16:27:49.000000000 +0200
> +++ wireless-testing/drivers/net/wireless/iwlwifi/iwl-agn.c 2008-12-09 16:31:25.000000000 +0200
> @@ -2972,12 +2972,6 @@ static int iwl_mac_hw_scan(struct ieee80
> goto out_unlock;
> }
>
> - if (priv->iw_mode == NL80211_IFTYPE_AP) { /* APs don't scan */
> - ret = -EIO;
> - IWL_ERROR("ERROR: APs don't scan\n");
> - goto out_unlock;
> - }
> -
> /* We don't schedule scan within next_scan_jiffies period.
> * Avoid scanning during possible EAPOL exchange, return
> * success immediately.
> Index: wireless-testing/drivers/net/wireless/iwlwifi/iwl3945-base.c
> ===================================================================
> --- wireless-testing.orig/drivers/net/wireless/iwlwifi/iwl3945-base.c 2008-12-09 16:34:51.000000000 +0200
> +++ wireless-testing/drivers/net/wireless/iwlwifi/iwl3945-base.c 2008-12-09 16:35:14.000000000 +0200
> @@ -2105,11 +2105,6 @@ static void iwl3945_setup_rxon_timing(st
>
> static int iwl3945_scan_initiate(struct iwl3945_priv *priv)
> {
> - if (priv->iw_mode == NL80211_IFTYPE_AP) {
> - IWL_ERROR("APs don't scan.\n");
> - return 0;
> - }
> -
> if (!iwl3945_is_ready_rf(priv)) {
> IWL_DEBUG_SCAN("Aborting scan due to not ready.\n");
> return -EIO;
> @@ -6991,12 +6986,6 @@ static int iwl3945_mac_hw_scan(struct ie
> goto out_unlock;
> }
>
> - if (priv->iw_mode == NL80211_IFTYPE_AP) { /* APs don't scan */
> - rc = -EIO;
> - IWL_ERROR("ERROR: APs don't scan\n");
> - goto out_unlock;
> - }
> -
> /* we don't schedule scan within next_scan_jiffies period */
> if (priv->next_scan_jiffies &&
> time_after(priv->next_scan_jiffies, jiffies)) {
> Index: wireless-testing/net/mac80211/wext.c
> ===================================================================
> --- wireless-testing.orig/net/mac80211/wext.c 2008-12-09 16:31:01.000000000 +0200
> +++ wireless-testing/net/mac80211/wext.c 2008-12-09 16:31:13.000000000 +0200
> @@ -418,8 +418,7 @@ static int ieee80211_ioctl_siwscan(struc
>
> if (sdata->vif.type != NL80211_IFTYPE_STATION &&
> sdata->vif.type != NL80211_IFTYPE_ADHOC &&
> - sdata->vif.type != NL80211_IFTYPE_MESH_POINT &&
> - sdata->vif.type != NL80211_IFTYPE_AP)
> + sdata->vif.type != NL80211_IFTYPE_MESH_POINT)
> return -EOPNOTSUPP;
>
> /* if SSID was specified explicitly then use that */
>
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