[PATCH 0/4] wireless: use channel bandwidth

[PATCH 0/4] wireless: use channel bandwidth

[Luis R. Rodriguez]

Few patches which actually make use of the channel bandwidth, lets
also send this to userspace as it useful to tell which channels you'll
be able to use HT40 or not on as a client.

Luis R. Rodriguez (4):
  cfg80211: check allowed channel max bandwidth before setting HT40
  mac80211: move early error branch check on ieee80211_set_freq()
  mac80211: disallow HT40 if max channel bandwidth is less than 40 MHz
  cfg80211: send channel max bandwidth to userspace

 include/linux/nl80211.h |    3 +++
 net/mac80211/util.c     |   30 +++++++++++++++++-------------
 net/wireless/nl80211.c  |    9 ++++++++-
 3 files changed, 28 insertions(+), 14 deletions(-)

[PATCH 1/4] cfg80211: check allowed channel max bandwidth before setting HT40

[Luis R. Rodriguez]

Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
---
 net/wireless/nl80211.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 531bb67..08d4f55 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -398,6 +398,12 @@ static int nl80211_set_wiphy(struct sk_buff *skb, struct genl_info *info)
 		/* Primary channel not allowed */
 		if (!chan || chan->flags & IEEE80211_CHAN_DISABLED)
 			goto bad_res;
+		/* You need 40 MHz for an HT40 channel */
+		if (channel_type == NL80211_CHAN_HT40PLUS ||
+		    channel_type == NL80211_CHAN_HT40MINUS) {
+			if (chan->max_bandwidth < 40)
+				goto bad_res;
+		}
 
 		if (channel_type == NL80211_CHAN_HT40MINUS)
 			sec_freq = freq - 20;
-- 
1.6.0.6

[PATCH 2/4] mac80211: move early error branch check on ieee80211_set_freq()

[Luis R. Rodriguez]

This has no functional change, we just move the bad case error check
early as we will soon add some more and this will make this easier to
read.

Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
---
 net/mac80211/util.c |   27 ++++++++++++++-------------
 1 files changed, 14 insertions(+), 13 deletions(-)

diff --git a/net/mac80211/util.c b/net/mac80211/util.c
index e0431a1..32610a0 100644
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -793,19 +793,20 @@ int ieee80211_set_freq(struct ieee80211_sub_if_data *sdata, int freqMHz)
 
 	chan = ieee80211_get_channel(local->hw.wiphy, freqMHz);
 
-	if (chan && !(chan->flags & IEEE80211_CHAN_DISABLED)) {
-		if (sdata->vif.type == NL80211_IFTYPE_ADHOC &&
-		    chan->flags & IEEE80211_CHAN_NO_IBSS)
-			return ret;
-		local->oper_channel = chan;
-		local->oper_channel_type = NL80211_CHAN_NO_HT;
-
-		if (local->sw_scanning || local->hw_scanning)
-			ret = 0;
-		else
-			ret = ieee80211_hw_config(
-				local, IEEE80211_CONF_CHANGE_CHANNEL);
-	}
+	if (!chan || (chan->flags & IEEE80211_CHAN_DISABLED))
+		return ret;
+
+	if (sdata->vif.type == NL80211_IFTYPE_ADHOC &&
+	    chan->flags & IEEE80211_CHAN_NO_IBSS)
+		return ret;
+	local->oper_channel = chan;
+	local->oper_channel_type = NL80211_CHAN_NO_HT;
+
+	if (local->sw_scanning || local->hw_scanning)
+		ret = 0;
+	else
+		ret = ieee80211_hw_config(
+			local, IEEE80211_CONF_CHANGE_CHANNEL);
 
 	return ret;
 }
-- 
1.6.0.6

[PATCH 3/4] mac80211: disallow HT40 if max channel bandwidth is less than 40 MHz

[Luis R. Rodriguez]

Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
---
 net/mac80211/util.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/net/mac80211/util.c b/net/mac80211/util.c
index 32610a0..a891d7e 100644
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -796,6 +796,9 @@ int ieee80211_set_freq(struct ieee80211_sub_if_data *sdata, int freqMHz)
 	if (!chan || (chan->flags & IEEE80211_CHAN_DISABLED))
 		return ret;
 
+	if (conf_is_ht40(&local->hw.conf) && chan->max_bandwidth < 40)
+		return ret;
+
 	if (sdata->vif.type == NL80211_IFTYPE_ADHOC &&
 	    chan->flags & IEEE80211_CHAN_NO_IBSS)
 		return ret;
-- 
1.6.0.6

Re: [PATCH 3/4] mac80211: disallow HT40 if max channel bandwidth is less than 40 MHz

[Johannes Berg]

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On Mon, 2009-03-09 at 22:04 -0400, Luis R. Rodriguez wrote:
> Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
> ---
>  net/mac80211/util.c |    3 +++
>  1 files changed, 3 insertions(+), 0 deletions(-)
> 
> diff --git a/net/mac80211/util.c b/net/mac80211/util.c
> index 32610a0..a891d7e 100644
> --- a/net/mac80211/util.c
> +++ b/net/mac80211/util.c
> @@ -796,6 +796,9 @@ int ieee80211_set_freq(struct ieee80211_sub_if_data *sdata, int freqMHz)
>  	if (!chan || (chan->flags & IEEE80211_CHAN_DISABLED))
>  		return ret;
>  
> +	if (conf_is_ht40(&local->hw.conf) && chan->max_bandwidth < 40)
> +		return ret;
> +

You just made nl80211 check this, why bother adding it here too?

johannes

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Re: [PATCH 3/4] mac80211: disallow HT40 if max channel bandwidth is less than 40 MHz

[Luis R. Rodriguez]

On Tue, Mar 10, 2009 at 12:15 AM, Johannes Berg
<johannes@sipsolutions.net> wrote:
> On Mon, 2009-03-09 at 22:04 -0400, Luis R. Rodriguez wrote:
>> Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
>> ---
>> =C2=A0net/mac80211/util.c | =C2=A0 =C2=A03 +++
>> =C2=A01 files changed, 3 insertions(+), 0 deletions(-)
>>
>> diff --git a/net/mac80211/util.c b/net/mac80211/util.c
>> index 32610a0..a891d7e 100644
>> --- a/net/mac80211/util.c
>> +++ b/net/mac80211/util.c
>> @@ -796,6 +796,9 @@ int ieee80211_set_freq(struct ieee80211_sub_if_d=
ata *sdata, int freqMHz)
>> =C2=A0 =C2=A0 =C2=A0 if (!chan || (chan->flags & IEEE80211_CHAN_DISA=
BLED))
>> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 return ret;
>>
>> + =C2=A0 =C2=A0 if (conf_is_ht40(&local->hw.conf) && chan->max_bandw=
idth < 40)
>> + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 return ret;
>> +
>
> You just made nl80211 check this, why bother adding it here too?

Wext crap.

  Luis
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Re: [PATCH 3/4] mac80211: disallow HT40 if max channel bandwidth is less than 40 MHz

[Johannes Berg]

[-- Attachment #1: Type: text/plain, Size: 373 bytes --]

On Tue, 2009-03-10 at 01:43 -0700, Luis R. Rodriguez wrote:

> >> +     if (conf_is_ht40(&local->hw.conf) && chan->max_bandwidth < 40)
> >> +             return ret;
> >> +
> >
> > You just made nl80211 check this, why bother adding it here too?
> 
> Wext crap.

Wext can't set ht40, it'll always reset back to 20mhz when you set
channel with wext.

johannes

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Re: [PATCH 3/4] mac80211: disallow HT40 if max channel bandwidth is less than 40 MHz

[Luis R. Rodriguez]

On Tue, Mar 10, 2009 at 1:46 AM, Johannes Berg
<johannes@sipsolutions.net> wrote:
> On Tue, 2009-03-10 at 01:43 -0700, Luis R. Rodriguez wrote:
>
>> >> + =C2=A0 =C2=A0 if (conf_is_ht40(&local->hw.conf) && chan->max_ba=
ndwidth < 40)
>> >> + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 return ret;
>> >> +
>> >
>> > You just made nl80211 check this, why bother adding it here too?
>>
>> Wext crap.
>
> Wext can't set ht40, it'll always reset back to 20mhz when you set
> channel with wext.

Ah, but we can eventually get there with setting the ssid, guess I'll
have to review that path.

  Luis
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[PATCH 4/4] cfg80211: send channel max bandwidth to userspace

[Luis R. Rodriguez]

Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
---
 include/linux/nl80211.h |    3 +++
 net/wireless/nl80211.c  |    3 ++-
 2 files changed, 5 insertions(+), 1 deletions(-)

diff --git a/include/linux/nl80211.h b/include/linux/nl80211.h
index f6e5637..55565a4 100644
--- a/include/linux/nl80211.h
+++ b/include/linux/nl80211.h
@@ -639,6 +639,7 @@ enum nl80211_band_attr {
  *	on this channel in current regulatory domain.
  * @NL80211_FREQUENCY_ATTR_MAX_TX_POWER: Maximum transmission power in mBm
  *	(100 * dBm).
+ * @NL80211_FREQUENCY_ATTR_MAX_BANDWIDTH: max bandwidth allowed, given in MHz
  */
 enum nl80211_frequency_attr {
 	__NL80211_FREQUENCY_ATTR_INVALID,
@@ -648,6 +649,7 @@ enum nl80211_frequency_attr {
 	NL80211_FREQUENCY_ATTR_NO_IBSS,
 	NL80211_FREQUENCY_ATTR_RADAR,
 	NL80211_FREQUENCY_ATTR_MAX_TX_POWER,
+	NL80211_FREQUENCY_ATTR_MAX_BANDWIDTH,
 
 	/* keep last */
 	__NL80211_FREQUENCY_ATTR_AFTER_LAST,
@@ -655,6 +657,7 @@ enum nl80211_frequency_attr {
 };
 
 #define NL80211_FREQUENCY_ATTR_MAX_TX_POWER NL80211_FREQUENCY_ATTR_MAX_TX_POWER
+#define NL80211_FREQUENCY_ATTR_MAX_BANDWIDTH NL80211_FREQUENCY_ATTR_MAX_BANDWIDTH
 
 /**
  * enum nl80211_bitrate_attr - bitrate attributes
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 08d4f55..4827020 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -207,9 +207,10 @@ static int nl80211_send_wiphy(struct sk_buff *msg, u32 pid, u32 seq, int flags,
 				NLA_PUT_FLAG(msg, NL80211_FREQUENCY_ATTR_NO_IBSS);
 			if (chan->flags & IEEE80211_CHAN_RADAR)
 				NLA_PUT_FLAG(msg, NL80211_FREQUENCY_ATTR_RADAR);
-
 			NLA_PUT_U32(msg, NL80211_FREQUENCY_ATTR_MAX_TX_POWER,
 				    DBM_TO_MBM(chan->max_power));
+			NLA_PUT_U32(msg, NL80211_FREQUENCY_ATTR_MAX_BANDWIDTH,
+				    chan->max_bandwidth);
 
 			nla_nest_end(msg, nl_freq);
 		}
-- 
1.6.0.6

Re: [PATCH 0/4] wireless: use channel bandwidth

[Johannes Berg]

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On Mon, 2009-03-09 at 22:04 -0400, Luis R. Rodriguez wrote:
> Few patches which actually make use of the channel bandwidth, lets
> also send this to userspace as it useful to tell which channels you'll
> be able to use HT40 or not on as a client.

Can you remind me why we have that max_bandwidth at all? It seems we
would be able to see whether ht40 fits by checking the above/below
sideband channel for use permission.

johannes

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Re: [PATCH 0/4] wireless: use channel bandwidth

[Luis R. Rodriguez]

On Tue, Mar 10, 2009 at 12:16 AM, Johannes Berg
<johannes@sipsolutions.net> wrote:
> On Mon, 2009-03-09 at 22:04 -0400, Luis R. Rodriguez wrote:
>> Few patches which actually make use of the channel bandwidth, lets
>> also send this to userspace as it useful to tell which channels you'll
>> be able to use HT40 or not on as a client.
>
> Can you remind me why we have that max_bandwidth at all? It seems we
> would be able to see whether ht40 fits by checking the above/below
> sideband channel for use permission.

To allow you to create bands for your regulatory domain and give easy
access to the allowed bandwidth. A good example is the world
regulatory domain right now with no HT40 for channels 12, 13 and 14.
cfg80211 does the checks for us only once upon regulatory domain
changes and that work gives us easy access to the allowed possible
channel width. The alternative is to call something like
freq_reg_info() on this call path and do the check in the places we
need.

Originally we had the NO-HT20 and NO-HT40 flags but as it turns out
HT20 is now allowed everywhere and we determine we can just use the
channel bandwidth to figure out whether or not you can use HT40.

  Luis