There's currently a very odd bug in mac80211 -- a
hardware scan that is done while the hardware is
really operating on 2.4 GHz will include CCK rates
in the probe request frame, even on 5 GHz (if the
driver uses the mac80211 IEs). Vice versa, if the
hardware is operating on 5 GHz the 2.4 GHz probe
requests will not include CCK rates even though
they should.
Fix this by splitting up cfg80211 scan requests by
band -- recalculating the IEs every time -- and
requesting only per-band scans from the driver.
Apparently this bug hasn't been a problem yet, but
it is imaginable that some older access points get
confused if confronted with such behaviour.
Signed-off-by: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>
---
net/mac80211/ieee80211_i.h | 8 +--
net/mac80211/scan.c | 96 +++++++++++++++++++++++++++++++++------------
net/mac80211/util.c | 8 ++-
3 files changed, 80 insertions(+), 32 deletions(-)
--- wireless-testing.orig/net/mac80211/ieee80211_i.h 2009-10-27 20:53:00.000000000 +0100
+++ wireless-testing/net/mac80211/ieee80211_i.h 2009-10-27 20:54:01.000000000 +0100
@@ -667,10 +667,9 @@ struct ieee80211_local {
unsigned long scanning;
struct cfg80211_ssid scan_ssid;
struct cfg80211_scan_request *int_scan_req;
- struct cfg80211_scan_request *scan_req;
+ struct cfg80211_scan_request *scan_req, *hw_scan_req;
struct ieee80211_channel *scan_channel;
- const u8 *orig_ies;
- int orig_ies_len;
+ enum ieee80211_band hw_scan_band;
int scan_channel_idx;
int scan_ies_len;
@@ -1050,7 +1049,8 @@ void ieee80211_send_auth(struct ieee8021
u8 *extra, size_t extra_len, const u8 *bssid,
const u8 *key, u8 key_len, u8 key_idx);
int ieee80211_build_preq_ies(struct ieee80211_local *local, u8 *buffer,
- const u8 *ie, size_t ie_len);
+ const u8 *ie, size_t ie_len,
+ enum ieee80211_band band);
void ieee80211_send_probe_req(struct ieee80211_sub_if_data *sdata, u8 *dst,
const u8 *ssid, size_t ssid_len,
const u8 *ie, size_t ie_len);
--- wireless-testing.orig/net/mac80211/scan.c 2009-10-27 20:53:00.000000000 +0100
+++ wireless-testing/net/mac80211/scan.c 2009-10-27 20:54:01.000000000 +0100
@@ -187,6 +187,39 @@ ieee80211_scan_rx(struct ieee80211_sub_i
return RX_QUEUED;
}
+/* return false if no more work */
+static bool ieee80211_prep_hw_scan(struct ieee80211_local *local)
+{
+ struct cfg80211_scan_request *req = local->scan_req;
+ enum ieee80211_band band;
+ int i, ielen, n_chans;
+
+ do {
+ if (local->hw_scan_band == IEEE80211_NUM_BANDS)
+ return false;
+
+ band = local->hw_scan_band;
+ n_chans = 0;
+ for (i = 0; i < req->n_channels; i++) {
+ if (req->channels[i]->band == band) {
+ local->hw_scan_req->channels[n_chans] =
+ req->channels[i];
+ n_chans++;
+ }
+ }
+
+ local->hw_scan_band++;
+ } while (!n_chans);
+
+ local->hw_scan_req->n_channels = n_chans;
+
+ ielen = ieee80211_build_preq_ies(local, (u8 *)local->hw_scan_req->ie,
+ req->ie, req->ie_len, band);
+ local->hw_scan_req->ie_len = ielen;
+
+ return true;
+}
+
/*
* inform AP that we will go to sleep so that it will buffer the frames
* while we scan
@@ -247,13 +280,6 @@ static void ieee80211_scan_ps_disable(st
}
}
-static void ieee80211_restore_scan_ies(struct ieee80211_local *local)
-{
- kfree(local->scan_req->ie);
- local->scan_req->ie = local->orig_ies;
- local->scan_req->ie_len = local->orig_ies_len;
-}
-
void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
{
struct ieee80211_local *local = hw_to_local(hw);
@@ -272,15 +298,22 @@ void ieee80211_scan_completed(struct iee
return;
}
- if (test_bit(SCAN_HW_SCANNING, &local->scanning))
- ieee80211_restore_scan_ies(local);
+ was_hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
+ if (was_hw_scan && !aborted && ieee80211_prep_hw_scan(local)) {
+ ieee80211_queue_delayed_work(&local->hw,
+ &local->scan_work, 0);
+ mutex_unlock(&local->scan_mtx);
+ return;
+ }
+
+ kfree(local->hw_scan_req);
+ local->hw_scan_req = NULL;
if (local->scan_req != local->int_scan_req)
cfg80211_scan_done(local->scan_req, aborted);
local->scan_req = NULL;
local->scan_sdata = NULL;
- was_hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
local->scanning = 0;
local->scan_channel = NULL;
@@ -392,19 +425,23 @@ static int __ieee80211_start_scan(struct
if (local->ops->hw_scan) {
u8 *ies;
- int ielen;
- ies = kmalloc(2 + IEEE80211_MAX_SSID_LEN +
- local->scan_ies_len + req->ie_len, GFP_KERNEL);
- if (!ies)
+ local->hw_scan_req = kmalloc(
+ sizeof(*local->hw_scan_req) +
+ req->n_channels * sizeof(req->channels[0]) +
+ 2 + IEEE80211_MAX_SSID_LEN + local->scan_ies_len +
+ req->ie_len, GFP_KERNEL);
+ if (!local->hw_scan_req)
return -ENOMEM;
- ielen = ieee80211_build_preq_ies(local, ies,
- req->ie, req->ie_len);
- local->orig_ies = req->ie;
- local->orig_ies_len = req->ie_len;
- req->ie = ies;
- req->ie_len = ielen;
+ local->hw_scan_req->ssids = req->ssids;
+ local->hw_scan_req->n_ssids = req->n_ssids;
+ ies = (u8 *)local->hw_scan_req +
+ sizeof(*local->hw_scan_req) +
+ req->n_channels * sizeof(req->channels[0]);
+ local->hw_scan_req->ie = ies;
+
+ local->hw_scan_band = 0;
}
local->scan_req = req;
@@ -436,16 +473,17 @@ static int __ieee80211_start_scan(struct
ieee80211_recalc_idle(local);
mutex_unlock(&local->scan_mtx);
- if (local->ops->hw_scan)
- rc = drv_hw_scan(local, local->scan_req);
- else
+ if (local->ops->hw_scan) {
+ WARN_ON(!ieee80211_prep_hw_scan(local));
+ rc = drv_hw_scan(local, local->hw_scan_req);
+ } else
rc = ieee80211_start_sw_scan(local);
mutex_lock(&local->scan_mtx);
if (rc) {
- if (local->ops->hw_scan)
- ieee80211_restore_scan_ies(local);
+ kfree(local->hw_scan_req);
+ local->hw_scan_req = NULL;
local->scanning = 0;
ieee80211_recalc_idle(local);
@@ -654,6 +692,14 @@ void ieee80211_scan_work(struct work_str
return;
}
+ if (local->hw_scan_req) {
+ int rc = drv_hw_scan(local, local->hw_scan_req);
+ mutex_unlock(&local->scan_mtx);
+ if (rc)
+ ieee80211_scan_completed(&local->hw, true);
+ return;
+ }
+
if (local->scan_req && !local->scanning) {
struct cfg80211_scan_request *req = local->scan_req;
int rc;
--- wireless-testing.orig/net/mac80211/util.c 2009-10-27 20:53:00.000000000 +0100
+++ wireless-testing/net/mac80211/util.c 2009-10-27 20:54:01.000000000 +0100
@@ -872,13 +872,14 @@ void ieee80211_send_auth(struct ieee8021
}
int ieee80211_build_preq_ies(struct ieee80211_local *local, u8 *buffer,
- const u8 *ie, size_t ie_len)
+ const u8 *ie, size_t ie_len,
+ enum ieee80211_band band)
{
struct ieee80211_supported_band *sband;
u8 *pos, *supp_rates_len, *esupp_rates_len = NULL;
int i;
- sband = local->hw.wiphy->bands[local->hw.conf.channel->band];
+ sband = local->hw.wiphy->bands[band];
pos = buffer;
@@ -966,7 +967,8 @@ void ieee80211_send_probe_req(struct iee
memcpy(pos, ssid, ssid_len);
pos += ssid_len;
- skb_put(skb, ieee80211_build_preq_ies(local, pos, ie, ie_len));
+ skb_put(skb, ieee80211_build_preq_ies(local, pos, ie, ie_len,
+ local->hw.conf.channel->band));
ieee80211_tx_skb(sdata, skb, 0);
}
--
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