From 36e6fea84905512ea776707e82b5b435220efc17 Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Wed, 12 Aug 2009 22:21:21 +0200 Subject: [PATCH] cfg80211: check for and abort dangling scan requests If you trigger a scan request on an interface and then take it down, or rmmod the module or unplug the device the driver might "forget" to cancel the scan request. That is a bug in the driver, but the current behaviour is that we just hang endlessly waiting for the netdev refcount to become 0 which it never will. To improve robustness, check for this situation in cfg80211, warn about it and clean up behind the driver. I don't just clean up silently because it's likely that the driver also has some internal state it has now leaked. Additionally, this fixes a locking bug, clearing the scan_req pointer should be done under the rdev lock. Finally, we also need to _wait_ for the scan work and not just abort it since it might be pending and wanting to do a cleanup. Signed-off-by: Johannes Berg Signed-off-by: John W. Linville --- net/wireless/core.c | 10 +++++++++- net/wireless/core.h | 1 + net/wireless/scan.c | 26 ++++++++++++++++---------- 3 files changed, 26 insertions(+), 11 deletions(-) diff --git a/net/wireless/core.c b/net/wireless/core.c index e630648fef79..35d83bedfe5b 100644 --- a/net/wireless/core.c +++ b/net/wireless/core.c @@ -601,8 +601,8 @@ void wiphy_unregister(struct wiphy *wiphy) mutex_unlock(&cfg80211_mutex); + flush_work(&rdev->scan_done_wk); cancel_work_sync(&rdev->conn_work); - cancel_work_sync(&rdev->scan_done_wk); kfree(rdev->scan_req); flush_work(&rdev->event_work); } @@ -728,6 +728,13 @@ static int cfg80211_netdev_notifier_call(struct notifier_block * nb, #endif break; case NETDEV_UNREGISTER: + cfg80211_lock_rdev(rdev); + + if (WARN_ON(rdev->scan_req && rdev->scan_req->dev == dev)) { + rdev->scan_req->aborted = true; + ___cfg80211_scan_done(rdev); + } + mutex_lock(&rdev->devlist_mtx); /* * It is possible to get NETDEV_UNREGISTER @@ -746,6 +753,7 @@ static int cfg80211_netdev_notifier_call(struct notifier_block * nb, #endif } mutex_unlock(&rdev->devlist_mtx); + cfg80211_unlock_rdev(rdev); break; case NETDEV_PRE_UP: if (!(wdev->wiphy->interface_modes & BIT(wdev->iftype))) diff --git a/net/wireless/core.h b/net/wireless/core.h index f7be3a9b427e..c603f5286326 100644 --- a/net/wireless/core.h +++ b/net/wireless/core.h @@ -368,6 +368,7 @@ void cfg80211_sme_scan_done(struct net_device *dev); void cfg80211_sme_rx_auth(struct net_device *dev, const u8 *buf, size_t len); void cfg80211_sme_disassoc(struct net_device *dev, int idx); void __cfg80211_scan_done(struct work_struct *wk); +void ___cfg80211_scan_done(struct cfg80211_registered_device *rdev); void cfg80211_upload_connect_keys(struct wireless_dev *wdev); struct ieee80211_channel * diff --git a/net/wireless/scan.c b/net/wireless/scan.c index e6c1f11595da..fe575a24c95c 100644 --- a/net/wireless/scan.c +++ b/net/wireless/scan.c @@ -18,19 +18,14 @@ #define IEEE80211_SCAN_RESULT_EXPIRE (15 * HZ) -void __cfg80211_scan_done(struct work_struct *wk) +void ___cfg80211_scan_done(struct cfg80211_registered_device *rdev) { - struct cfg80211_registered_device *rdev; struct cfg80211_scan_request *request; struct net_device *dev; #ifdef CONFIG_WIRELESS_EXT union iwreq_data wrqu; #endif - rdev = container_of(wk, struct cfg80211_registered_device, - scan_done_wk); - - mutex_lock(&rdev->mtx); request = rdev->scan_req; dev = request->dev; @@ -43,9 +38,9 @@ void __cfg80211_scan_done(struct work_struct *wk) cfg80211_sme_scan_done(dev); if (request->aborted) - nl80211_send_scan_aborted(wiphy_to_dev(request->wiphy), dev); + nl80211_send_scan_aborted(rdev, dev); else - nl80211_send_scan_done(wiphy_to_dev(request->wiphy), dev); + nl80211_send_scan_done(rdev, dev); #ifdef CONFIG_WIRELESS_EXT if (!request->aborted) { @@ -57,11 +52,22 @@ void __cfg80211_scan_done(struct work_struct *wk) dev_put(dev); - cfg80211_unlock_rdev(rdev); - wiphy_to_dev(request->wiphy)->scan_req = NULL; + rdev->scan_req = NULL; kfree(request); } +void __cfg80211_scan_done(struct work_struct *wk) +{ + struct cfg80211_registered_device *rdev; + + rdev = container_of(wk, struct cfg80211_registered_device, + scan_done_wk); + + cfg80211_lock_rdev(rdev); + ___cfg80211_scan_done(rdev); + cfg80211_unlock_rdev(rdev); +} + void cfg80211_scan_done(struct cfg80211_scan_request *request, bool aborted) { WARN_ON(request != wiphy_to_dev(request->wiphy)->scan_req); -- 2.20.1