If cfg80211 requests a scan it awaits either a return code != 0 from
the scan function or the cfg80211_scan_done to be called. In case of
a STA mac80211's scan function ever returns 0 and queues the scan request.
If ieee80211_sta_work is executed and ieee80211_start_scan fails for
some reason cfg80211_scan_done will never be called but cfg80211 still
thinks the scan was triggered successfully and will refuse any future
scan requests due to drv->scan_req not being cleaned up.
If a scan is triggered from within the MLME a similar problem appears. If
ieee80211_start_scan returns an error, local->scan_req will not be reset
and mac80211 will refuse any future scan requests.
Hence, in both cases call ieee80211_scan_failed (which notifies cfg80211
and resets local->scan_req) if ieee80211_start_scan returns an error.
Signed-off-by: Helmut Schaa <helmut.schaa@xxxxxxxxxxxxxx>
---
It just happend to me that after rf-killing iwlwifi wpa_supplicant triggered
a scan (which was accepted by mac80211 as it is not rfkill aware yet) which
failed in iwlwifi and left cfg80211 in a state where it won't accept a new
scan request even after unkilling the radio again.
Johannes, do you think it is worth to add something like a scan watchdog that
triggers after 30 seconds to cfg80211 and prints "scan request failed", cancels
the scan request and notifies user space?
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index ecbc8e0..fbb91f1 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -972,6 +972,7 @@ int ieee80211_sta_set_extra_ie(struct ieee80211_sub_if_data *sdata,
char *ie, size_t len);
void ieee80211_mlme_notify_scan_completed(struct ieee80211_local *local);
+void ieee80211_scan_failed(struct ieee80211_local *local);
int ieee80211_start_scan(struct ieee80211_sub_if_data *scan_sdata,
struct cfg80211_scan_request *req);
struct ieee80211_bss *
diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index eeb6da8..6e92674 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -1720,7 +1720,10 @@ static int ieee80211_sta_config_auth(struct ieee80211_sub_if_data *sdata)
local->int_scan_req.ssids[0].ssid_len = 0;
else
local->int_scan_req.ssids[0].ssid_len = ifmgd->ssid_len;
- ieee80211_start_scan(sdata, &local->int_scan_req);
+
+ if (ieee80211_start_scan(sdata, &local->int_scan_req))
+ ieee80211_scan_failed(local);
+
ifmgd->state = IEEE80211_STA_MLME_AUTHENTICATE;
set_bit(IEEE80211_STA_REQ_AUTH, &ifmgd->request);
} else {
@@ -1757,7 +1760,14 @@ static void ieee80211_sta_work(struct work_struct *work)
ifmgd->state != IEEE80211_STA_MLME_AUTHENTICATE &&
ifmgd->state != IEEE80211_STA_MLME_ASSOCIATE &&
test_and_clear_bit(IEEE80211_STA_REQ_SCAN, &ifmgd->request)) {
- ieee80211_start_scan(sdata, local->scan_req);
+ /*
+ * The call to ieee80211_start_scan can fail but ieee80211_request_scan
+ * (which queued ieee80211_sta_work) did not return an error. Thus, call
+ * ieee80211_scan_failed here if ieee80211_start_scan fails in order to
+ * notify the scan requester.
+ */
+ if (ieee80211_start_scan(sdata, local->scan_req))
+ ieee80211_scan_failed(local);
return;
}
diff --git a/net/mac80211/scan.c b/net/mac80211/scan.c
index 0e81e16..5030a3c 100644
--- a/net/mac80211/scan.c
+++ b/net/mac80211/scan.c
@@ -202,6 +202,18 @@ ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb,
return RX_QUEUED;
}
+void ieee80211_scan_failed(struct ieee80211_local *local)
+{
+ if (WARN_ON(!local->scan_req))
+ return;
+
+ /* notify cfg80211 about the failed scan */
+ if (local->scan_req != &local->int_scan_req)
+ cfg80211_scan_done(local->scan_req, true);
+
+ local->scan_req = NULL;
+}
+
void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
{
struct ieee80211_local *local = hw_to_local(hw);
--
To unsubscribe from this list: send the line "unsubscribe linux-wireless" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
