diff mbox

[v1] cfg80211: Fix regulatory check for 60GHz band frequencies

Message ID 1347364329-19443-2-git-send-email-qca_vkondrat@qca.qualcomm.com (mailing list archive)
State Not Applicable, archived
Headers show

Commit Message

Vladimir Kondratiev Sept. 11, 2012, 11:52 a.m. UTC 
Remove freq_in_rule_band, that was used to optimize regulatory rules check.
Approach used in the freq_in_rule_band is incorrect for 60GHz band,
where channel spacing is 2.160GHz.
Also, it does not really add any optimization, since real check for frequency fit is
always performed.

Issue exposed in the following way: 60g band defines 3 channels supported wold-wide:
channels 1..3 or 58320, 60480, 62640 MHz, and channel 4, or 64800 MHz,
in the most of the world, with 2160 MHz spacing.
Corresponded regulatory rule for channels 1..3 would be
(57240 - 63720 @ 2160)

And, when regulatory applies to the channel 2 (60480), it get disabled since it is
more then 2GHz from either frequency boundary and freq_in_rule_band fails

Signed-off-by: Vladimir Kondratiev <qca_vkondrat@qca.qualcomm.com>
---
 net/wireless/reg.c |   54 ++++++----------------------------------------------
 1 file changed, 6 insertions(+), 48 deletions(-)

Comments

Luis R. Rodriguez Sept. 13, 2012, 7:03 p.m. UTC | #1 
On Tue, Sep 11, 2012 at 4:52 AM, Vladimir Kondratiev
<qca_vkondrat@qca.qualcomm.com> wrote:
> Remove freq_in_rule_band, that was used to optimize regulatory rules check.
> Approach used in the freq_in_rule_band is incorrect for 60GHz band,
> where channel spacing is 2.160GHz.
> Also, it does not really add any optimization, since real check for frequency fit is
> always performed.
>
> Issue exposed in the following way: 60g band defines 3 channels supported wold-wide:
> channels 1..3 or 58320, 60480, 62640 MHz, and channel 4, or 64800 MHz,
> in the most of the world, with 2160 MHz spacing.
> Corresponded regulatory rule for channels 1..3 would be
> (57240 - 63720 @ 2160)
>
> And, when regulatory applies to the channel 2 (60480), it get disabled since it is
> more then 2GHz from either frequency boundary and freq_in_rule_band fails
>
> Signed-off-by: Vladimir Kondratiev <qca_vkondrat@qca.qualcomm.com>

NACK - please check the usage of -ERANGE returned here for its users.
It turns out that Country IEs are allowed to be sent by APs whereby
specific bands are not specified even though those bands are allowed
in that country, and although the device supports them. In such cases
without a band check like this if a country IE is issued with say only
2.4 GHz rules we'd end up disabling all 5 GHz and 60 GHz rules. What
the check does then is if we get an country IE we ensure that before
we disable channels on a band we ensure that the country IE has at
least one channel on the band. Otherwise we leave that band alone.

With your patch we'd break previous behavior where an AP may send a
country IE only for 2.4 GHz and force us to disable all of our 5 GHz
channels. We don't want that.

  Luis
--
To unsubscribe from this list: send the line "unsubscribe linux-wireless" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
diff mbox

Patch

diff --git a/net/wireless/reg.c b/net/wireless/reg.c
index 1ad04e5..5b0dc05 100644
--- a/net/wireless/reg.c
+++ b/net/wireless/reg.c
@@ -497,31 +497,6 @@  static bool reg_does_bw_fit(const struct ieee80211_freq_range *freq_range,
 	return false;
 }
 
-/**
- * freq_in_rule_band - tells us if a frequency is in a frequency band
- * @freq_range: frequency rule we want to query
- * @freq_khz: frequency we are inquiring about
- *
- * This lets us know if a specific frequency rule is or is not relevant to
- * a specific frequency's band. Bands are device specific and artificial
- * definitions (the "2.4 GHz band" and the "5 GHz band"), however it is
- * safe for now to assume that a frequency rule should not be part of a
- * frequency's band if the start freq or end freq are off by more than 2 GHz.
- * This resolution can be lowered and should be considered as we add
- * regulatory rule support for other "bands".
- **/
-static bool freq_in_rule_band(const struct ieee80211_freq_range *freq_range,
-	u32 freq_khz)
-{
-#define ONE_GHZ_IN_KHZ	1000000
-	if (abs(freq_khz - freq_range->start_freq_khz) <= (2 * ONE_GHZ_IN_KHZ))
-		return true;
-	if (abs(freq_khz - freq_range->end_freq_khz) <= (2 * ONE_GHZ_IN_KHZ))
-		return true;
-	return false;
-#undef ONE_GHZ_IN_KHZ
-}
-
 /*
  * Helper for regdom_intersect(), this does the real
  * mathematical intersection fun
@@ -692,9 +667,7 @@  static int freq_reg_info_regd(struct wiphy *wiphy,
 			      const struct ieee80211_regdomain *custom_regd)
 {
 	int i;
-	bool band_rule_found = false;
 	const struct ieee80211_regdomain *regd;
-	bool bw_fits = false;
 
 	if (!desired_bw_khz)
 		desired_bw_khz = MHZ_TO_KHZ(20);
@@ -715,33 +688,18 @@  static int freq_reg_info_regd(struct wiphy *wiphy,
 		return -EINVAL;
 
 	for (i = 0; i < regd->n_reg_rules; i++) {
-		const struct ieee80211_reg_rule *rr;
-		const struct ieee80211_freq_range *fr = NULL;
+		const struct ieee80211_reg_rule *rr = &regd->reg_rules[i];
+		const struct ieee80211_freq_range *fr = &rr->freq_range;
+		bool bw_fits = reg_does_bw_fit(fr,
+					       center_freq,
+					       desired_bw_khz);
 
-		rr = &regd->reg_rules[i];
-		fr = &rr->freq_range;
-
-		/*
-		 * We only need to know if one frequency rule was
-		 * was in center_freq's band, that's enough, so lets
-		 * not overwrite it once found
-		 */
-		if (!band_rule_found)
-			band_rule_found = freq_in_rule_band(fr, center_freq);
-
-		bw_fits = reg_does_bw_fit(fr,
-					  center_freq,
-					  desired_bw_khz);
-
-		if (band_rule_found && bw_fits) {
+		if (bw_fits) {
 			*reg_rule = rr;
 			return 0;
 		}
 	}
 
-	if (!band_rule_found)
-		return -ERANGE;
-
 	return -EINVAL;
 }