cfg80211: make spurious warnings less likely, configurable

Bob reported that he got warnings in IBSS mode about
the ssid_len being zero on a joined event, but only
when kmemcheck was enabled. This appears to be due
to a race condition between drivers and userspace,
when the driver reports joined but the user in the
meantime decided to leave the IBSS again, the warning
would trigger. This was made more likely by kmemcheck
delaying the code that does the check and sends the
event.

So first, make the warning trigger closer to the
driver, which means it's not locked, but since only
the warning depends on it that's ok.

And secondly, users will not want to have spurious
warnings at all, so make those that are known to be
racy in such a way configurable.

Reported-by: Bob Copeland <me@bobcopeland.com>
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 9 insertions, 3 deletions

diff --git a/net/wireless/sme.c b/net/wireless/sme.c
index 4a8289f9b4f0..68307883ec87 100644
--- a/net/wireless/sme.c
+++ b/net/wireless/sme.c
@@ -351,7 +351,7 @@ void __cfg80211_connect_result(struct net_device *dev, const u8 *bssid,
         if (WARN_ON(wdev->iftype != NL80211_IFTYPE_STATION))
                 return;
 
-        if (WARN_ON(wdev->sme_state != CFG80211_SME_CONNECTING))
+        if (wdev->sme_state != CFG80211_SME_CONNECTING)
                 return;
 
         nl80211_send_connect_result(wiphy_to_dev(wdev->wiphy), dev,
@@ -445,6 +445,8 @@ void cfg80211_connect_result(struct net_device *dev, const u8 *bssid,
         struct cfg80211_event *ev;
         unsigned long flags;
 
+        CFG80211_DEV_WARN_ON(wdev->sme_state != CFG80211_SME_CONNECTING);
+
         ev = kzalloc(sizeof(*ev) + req_ie_len + resp_ie_len, gfp);
         if (!ev)
                 return;
@@ -481,7 +483,7 @@ void __cfg80211_roamed(struct wireless_dev *wdev, const u8 *bssid,
         if (WARN_ON(wdev->iftype != NL80211_IFTYPE_STATION))
                 return;
 
-        if (WARN_ON(wdev->sme_state != CFG80211_SME_CONNECTED))
+        if (wdev->sme_state != CFG80211_SME_CONNECTED)
                 return;
 
         /* internal error -- how did we get to CONNECTED w/o BSS? */
@@ -540,6 +542,8 @@ void cfg80211_roamed(struct net_device *dev, const u8 *bssid,
         struct cfg80211_event *ev;
         unsigned long flags;
 
+        CFG80211_DEV_WARN_ON(wdev->sme_state != CFG80211_SME_CONNECTED);
+
         ev = kzalloc(sizeof(*ev) + req_ie_len + resp_ie_len, gfp);
         if (!ev)
                 return;
@@ -575,7 +579,7 @@ void __cfg80211_disconnected(struct net_device *dev, const u8 *ie,
         if (WARN_ON(wdev->iftype != NL80211_IFTYPE_STATION))
                 return;
 
-        if (WARN_ON(wdev->sme_state != CFG80211_SME_CONNECTED))
+        if (wdev->sme_state != CFG80211_SME_CONNECTED)
                 return;
 
         if (wdev->current_bss) {
@@ -639,6 +643,8 @@ void cfg80211_disconnected(struct net_device *dev, u16 reason,
         struct cfg80211_event *ev;
         unsigned long flags;
 
+        CFG80211_DEV_WARN_ON(wdev->sme_state != CFG80211_SME_CONNECTED);
+
         ev = kzalloc(sizeof(*ev) + ie_len, gfp);
         if (!ev)
                 return;