From c10841ca722a0bc960dc541c51582773f9a24f98 Mon Sep 17 00:00:00 2001 From: Luciano Coelho Date: Thu, 30 Jun 2011 08:32:41 +0300 Subject: [PATCH] cfg80211: fix deadlock with rfkill/sched_scan by adding new mutex There was a deadlock when rfkill-blocking a wireless interface, because we were locking the rdev mutex on NETDEV_GOING_DOWN to stop sched_scans that were eventually running. The rfkill block code was already holding a mutex under rdev: kernel: ======================================================= kernel: [ INFO: possible circular locking dependency detected ] kernel: 3.0.0-rc1-00049-g1fa7b6a #57 kernel: ------------------------------------------------------- kernel: kworker/0:1/4525 is trying to acquire lock: kernel: (&rdev->mtx){+.+.+.}, at: [] cfg80211_netdev_notifier_call+0x131/0x5b0 kernel: kernel: but task is already holding lock: kernel: (&rdev->devlist_mtx){+.+.+.}, at: [] cfg80211_rfkill_set_block+0x4f/0xa0 kernel: kernel: which lock already depends on the new lock. To fix this, add a new mutex specifically for sched_scan, to protect the sched_scan_req element in the rdev struct, instead of using the global rdev mutex. Reported-by: Duane Griffin Signed-off-by: Luciano Coelho Signed-off-by: John W. Linville --- net/wireless/core.c | 12 +++++++++--- net/wireless/core.h | 2 ++ net/wireless/nl80211.c | 24 ++++++++++++++++++------ net/wireless/scan.c | 10 +++++----- 4 files changed, 34 insertions(+), 14 deletions(-) diff --git a/net/wireless/core.c b/net/wireless/core.c index c22ef3492ee6..880dbe2e6f94 100644 --- a/net/wireless/core.c +++ b/net/wireless/core.c @@ -366,6 +366,7 @@ struct wiphy *wiphy_new(const struct cfg80211_ops *ops, int sizeof_priv) mutex_init(&rdev->mtx); mutex_init(&rdev->devlist_mtx); + mutex_init(&rdev->sched_scan_mtx); INIT_LIST_HEAD(&rdev->netdev_list); spin_lock_init(&rdev->bss_lock); INIT_LIST_HEAD(&rdev->bss_list); @@ -701,6 +702,7 @@ void cfg80211_dev_free(struct cfg80211_registered_device *rdev) rfkill_destroy(rdev->rfkill); mutex_destroy(&rdev->mtx); mutex_destroy(&rdev->devlist_mtx); + mutex_destroy(&rdev->sched_scan_mtx); list_for_each_entry_safe(scan, tmp, &rdev->bss_list, list) cfg80211_put_bss(&scan->pub); cfg80211_rdev_free_wowlan(rdev); @@ -737,12 +739,16 @@ static void wdev_cleanup_work(struct work_struct *work) ___cfg80211_scan_done(rdev, true); } + cfg80211_unlock_rdev(rdev); + + mutex_lock(&rdev->sched_scan_mtx); + if (WARN_ON(rdev->sched_scan_req && rdev->sched_scan_req->dev == wdev->netdev)) { __cfg80211_stop_sched_scan(rdev, false); } - cfg80211_unlock_rdev(rdev); + mutex_unlock(&rdev->sched_scan_mtx); mutex_lock(&rdev->devlist_mtx); rdev->opencount--; @@ -830,9 +836,9 @@ static int cfg80211_netdev_notifier_call(struct notifier_block * nb, break; case NL80211_IFTYPE_P2P_CLIENT: case NL80211_IFTYPE_STATION: - cfg80211_lock_rdev(rdev); + mutex_lock(&rdev->sched_scan_mtx); __cfg80211_stop_sched_scan(rdev, false); - cfg80211_unlock_rdev(rdev); + mutex_unlock(&rdev->sched_scan_mtx); wdev_lock(wdev); #ifdef CONFIG_CFG80211_WEXT diff --git a/net/wireless/core.h b/net/wireless/core.h index 3dce1f167eba..a570ff9214ec 100644 --- a/net/wireless/core.h +++ b/net/wireless/core.h @@ -65,6 +65,8 @@ struct cfg80211_registered_device { struct work_struct scan_done_wk; struct work_struct sched_scan_results_wk; + struct mutex sched_scan_mtx; + #ifdef CONFIG_NL80211_TESTMODE struct genl_info *testmode_info; #endif diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c index f07602d7bf68..cea338150d05 100644 --- a/net/wireless/nl80211.c +++ b/net/wireless/nl80211.c @@ -3461,9 +3461,6 @@ static int nl80211_start_sched_scan(struct sk_buff *skb, if (!is_valid_ie_attr(info->attrs[NL80211_ATTR_IE])) return -EINVAL; - if (rdev->sched_scan_req) - return -EINPROGRESS; - if (!info->attrs[NL80211_ATTR_SCHED_SCAN_INTERVAL]) return -EINVAL; @@ -3502,12 +3499,21 @@ static int nl80211_start_sched_scan(struct sk_buff *skb, if (ie_len > wiphy->max_scan_ie_len) return -EINVAL; + mutex_lock(&rdev->sched_scan_mtx); + + if (rdev->sched_scan_req) { + err = -EINPROGRESS; + goto out; + } + request = kzalloc(sizeof(*request) + sizeof(*request->ssids) * n_ssids + sizeof(*request->channels) * n_channels + ie_len, GFP_KERNEL); - if (!request) - return -ENOMEM; + if (!request) { + err = -ENOMEM; + goto out; + } if (n_ssids) request->ssids = (void *)&request->channels[n_channels]; @@ -3605,6 +3611,7 @@ static int nl80211_start_sched_scan(struct sk_buff *skb, out_free: kfree(request); out: + mutex_unlock(&rdev->sched_scan_mtx); return err; } @@ -3612,12 +3619,17 @@ static int nl80211_stop_sched_scan(struct sk_buff *skb, struct genl_info *info) { struct cfg80211_registered_device *rdev = info->user_ptr[0]; + int err; if (!(rdev->wiphy.flags & WIPHY_FLAG_SUPPORTS_SCHED_SCAN) || !rdev->ops->sched_scan_stop) return -EOPNOTSUPP; - return __cfg80211_stop_sched_scan(rdev, false); + mutex_lock(&rdev->sched_scan_mtx); + err = __cfg80211_stop_sched_scan(rdev, false); + mutex_unlock(&rdev->sched_scan_mtx); + + return err; } static int nl80211_send_bss(struct sk_buff *msg, u32 pid, u32 seq, int flags, diff --git a/net/wireless/scan.c b/net/wireless/scan.c index 7a6c67667d70..ae0c2256ba3b 100644 --- a/net/wireless/scan.c +++ b/net/wireless/scan.c @@ -100,14 +100,14 @@ void __cfg80211_sched_scan_results(struct work_struct *wk) rdev = container_of(wk, struct cfg80211_registered_device, sched_scan_results_wk); - cfg80211_lock_rdev(rdev); + mutex_lock(&rdev->sched_scan_mtx); /* we don't have sched_scan_req anymore if the scan is stopping */ if (rdev->sched_scan_req) nl80211_send_sched_scan_results(rdev, rdev->sched_scan_req->dev); - cfg80211_unlock_rdev(rdev); + mutex_unlock(&rdev->sched_scan_mtx); } void cfg80211_sched_scan_results(struct wiphy *wiphy) @@ -123,9 +123,9 @@ void cfg80211_sched_scan_stopped(struct wiphy *wiphy) { struct cfg80211_registered_device *rdev = wiphy_to_dev(wiphy); - cfg80211_lock_rdev(rdev); + mutex_lock(&rdev->sched_scan_mtx); __cfg80211_stop_sched_scan(rdev, true); - cfg80211_unlock_rdev(rdev); + mutex_unlock(&rdev->sched_scan_mtx); } EXPORT_SYMBOL(cfg80211_sched_scan_stopped); @@ -135,7 +135,7 @@ int __cfg80211_stop_sched_scan(struct cfg80211_registered_device *rdev, int err; struct net_device *dev; - ASSERT_RDEV_LOCK(rdev); + lockdep_assert_held(&rdev->sched_scan_mtx); if (!rdev->sched_scan_req) return 0;