[PATCH 2/3] mac80211: Support dynamic AP mode channel width changes

[PATCH 2/3] mac80211: Support dynamic AP mode channel width changes

[Jouni Malinen]

Implement the new cfg80211 capability to enable mac80211-based drivers
to support for dynamic channel bandwidth changes (e.g., HT 20/40 MHz
changes).

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>
---
 net/mac80211/cfg.c |   16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index aaa59d7..1ce407a 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -3949,6 +3949,21 @@ static int ieee80211_set_qos_map(struct wiphy *wiphy,
 	return 0;
 }
 
+static int ieee80211_set_ap_channel(struct wiphy *wiphy,
+				    struct net_device *dev,
+				    struct cfg80211_chan_def *chandef)
+{
+	struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
+	int ret;
+	u32 changed = 0;
+
+	ret = ieee80211_vif_change_bandwidth(sdata, chandef, &changed);
+	if (ret == 0)
+		ieee80211_bss_info_change_notify(sdata, changed);
+
+	return ret;
+}
+
 const struct cfg80211_ops mac80211_config_ops = {
 	.add_virtual_intf = ieee80211_add_iface,
 	.del_virtual_intf = ieee80211_del_iface,
@@ -4029,4 +4044,5 @@ const struct cfg80211_ops mac80211_config_ops = {
 	.start_radar_detection = ieee80211_start_radar_detection,
 	.channel_switch = ieee80211_channel_switch,
 	.set_qos_map = ieee80211_set_qos_map,
+	.set_ap_channel = ieee80211_set_ap_channel,
 };
-- 
1.7.9.5


-- 
Jouni Malinen                                            PGP id EFC895FA

Re: [PATCH 2/3] mac80211: Support dynamic AP mode channel width changes

[Michal Kazior]

On 28 April 2014 10:22, Jouni Malinen <jouni@qca.qualcomm.com> wrote:
> Implement the new cfg80211 capability to enable mac80211-based drivers
> to support for dynamic channel bandwidth changes (e.g., HT 20/40 MHz
> changes).
>
> Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>
> ---
>  net/mac80211/cfg.c |   16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
>
> diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
> index aaa59d7..1ce407a 100644
> --- a/net/mac80211/cfg.c
> +++ b/net/mac80211/cfg.c
> @@ -3949,6 +3949,21 @@ static int ieee80211_set_qos_map(struct wiphy *wiphy,
>         return 0;
>  }
>
> +static int ieee80211_set_ap_channel(struct wiphy *wiphy,
> +                                   struct net_device *dev,
> +                                   struct cfg80211_chan_def *chandef)
> +{
> +       struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
> +       int ret;
> +       u32 changed = 0;
> +

Shouldn't interface combinations be verified here? What if there was a
bandwidth upgrade (after a downgrade) but in the meantime a vif with a
to-be incompatible chandef was brought up? I think the existing usage
of ieee80211_vif_change_bandwidth() in ieee80211_config_bw() already
suffers from this problem or am I missing something?


> +       ret = ieee80211_vif_change_bandwidth(sdata, chandef, &changed);
> +       if (ret == 0)
> +               ieee80211_bss_info_change_notify(sdata, changed);
> +
> +       return ret;
> +}


Michał

Re: [PATCH 2/3] mac80211: Support dynamic AP mode channel width changes

[Johannes Berg]

On Mon, 2014-04-28 at 10:57 +0200, Michal Kazior wrote:

> > +static int ieee80211_set_ap_channel(struct wiphy *wiphy,
> > +                                   struct net_device *dev,
> > +                                   struct cfg80211_chan_def *chandef)
> > +{
> > +       struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
> > +       int ret;
> > +       u32 changed = 0;
> > +
> 
> Shouldn't interface combinations be verified here? What if there was a
> bandwidth upgrade (after a downgrade) but in the meantime a vif with a
> to-be incompatible chandef was brought up?

Yeah that seems like a potential issue.

> I think the existing usage
> of ieee80211_vif_change_bandwidth() in ieee80211_config_bw() already
> suffers from this problem or am I missing something?

That sounds like you're arguing it should be fixed in a separate patch
to ieee80211_vif_change_bandwidth()? :)

johannes

Re: [PATCH 2/3] mac80211: Support dynamic AP mode channel width changes

[Johannes Berg]

On Mon, 2014-04-28 at 17:46 +0200, Johannes Berg wrote:

> > Shouldn't interface combinations be verified here? What if there was a
> > bandwidth upgrade (after a downgrade) but in the meantime a vif with a
> > to-be incompatible chandef was brought up?
> 
> Yeah that seems like a potential issue.

Hm, wait, isn't this addressed by this code in
ieee80211_vif_change_bandwidth():

        ctx = container_of(conf, struct ieee80211_chanctx, conf);
        if (!cfg80211_chandef_compatible(&conf->def, chandef)) { 
                ret = -EINVAL;
                goto out;
        }

johannes

Re: [PATCH 2/3] mac80211: Support dynamic AP mode channel width changes

[Michal Kazior]

On 28 April 2014 17:47, Johannes Berg <johannes@sipsolutions.net> wrote:
> On Mon, 2014-04-28 at 17:46 +0200, Johannes Berg wrote:
>
>> > Shouldn't interface combinations be verified here? What if there was a
>> > bandwidth upgrade (after a downgrade) but in the meantime a vif with a
>> > to-be incompatible chandef was brought up?
>>
>> Yeah that seems like a potential issue.
>
> Hm, wait, isn't this addressed by this code in
> ieee80211_vif_change_bandwidth():
>
>         ctx = container_of(conf, struct ieee80211_chanctx, conf);
>         if (!cfg80211_chandef_compatible(&conf->def, chandef)) {
>                 ret = -EINVAL;
>                 goto out;
>         }

Yeah, you're right.


Michał