From: Stanislaw Gruszka Date: Wed, 6 Oct 2010 09:22:09 +0000 (+0200) Subject: mac80211: keep lock when calling __ieee80211_scan_completed() X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=e229f844d7223b7063bea1e649203ac521a58fe1;p=linux-beck.git mac80211: keep lock when calling __ieee80211_scan_completed() We are taking local->mtx inside __ieee80211_scan_completed(), but just before call to that function we drop the lock. Dropping/taking lock is not good, because can lead to hard to understand race conditions. Patch split scan_completed() code into two functions, first must be called with local->mtx taken and second without it. Signed-off-by: Stanislaw Gruszka Acked-by: Johannes Berg Signed-off-by: John W. Linville --- diff --git a/net/mac80211/scan.c b/net/mac80211/scan.c index 830c02bc398a..6964a4598176 100644 --- a/net/mac80211/scan.c +++ b/net/mac80211/scan.c @@ -249,12 +249,12 @@ static bool ieee80211_prep_hw_scan(struct ieee80211_local *local) return true; } -static void __ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted) +static bool __ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted, + bool was_hw_scan) { struct ieee80211_local *local = hw_to_local(hw); - bool was_hw_scan; - mutex_lock(&local->mtx); + lockdep_assert_held(&local->mtx); /* * It's ok to abort a not-yet-running scan (that @@ -265,17 +265,13 @@ static void __ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted) if (WARN_ON(!local->scanning && !aborted)) aborted = true; - if (WARN_ON(!local->scan_req)) { - mutex_unlock(&local->mtx); - return; - } + if (WARN_ON(!local->scan_req)) + return false; - 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->mtx); - return; + return false; } kfree(local->hw_scan_req); @@ -289,23 +285,25 @@ static void __ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted) local->scanning = 0; local->scan_channel = NULL; - /* we only have to protect scan_req and hw/sw scan */ - mutex_unlock(&local->mtx); - - ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL); - if (was_hw_scan) - goto done; - - ieee80211_configure_filter(local); + return true; +} - drv_sw_scan_complete(local); +static void __ieee80211_scan_completed_finish(struct ieee80211_hw *hw, + bool was_hw_scan) +{ + struct ieee80211_local *local = hw_to_local(hw); - ieee80211_offchannel_return(local, true); + ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL); + if (!was_hw_scan) { + ieee80211_configure_filter(local); + drv_sw_scan_complete(local); + ieee80211_offchannel_return(local, true); + } - done: mutex_lock(&local->mtx); ieee80211_recalc_idle(local); mutex_unlock(&local->mtx); + ieee80211_mlme_notify_scan_completed(local); ieee80211_ibss_notify_scan_completed(local); ieee80211_mesh_notify_scan_completed(local); @@ -366,6 +364,8 @@ static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata, struct ieee80211_local *local = sdata->local; int rc; + lockdep_assert_held(&local->mtx); + if (local->scan_req) return -EBUSY; @@ -447,8 +447,8 @@ ieee80211_scan_get_channel_time(struct ieee80211_channel *chan) return IEEE80211_PROBE_DELAY + IEEE80211_CHANNEL_TIME; } -static int ieee80211_scan_state_decision(struct ieee80211_local *local, - unsigned long *next_delay) +static void ieee80211_scan_state_decision(struct ieee80211_local *local, + unsigned long *next_delay) { bool associated = false; bool tx_empty = true; @@ -458,12 +458,6 @@ static int ieee80211_scan_state_decision(struct ieee80211_local *local, struct ieee80211_sub_if_data *sdata; struct ieee80211_channel *next_chan; - /* if no more bands/channels left, complete scan and advance to the idle state */ - if (local->scan_channel_idx >= local->scan_req->n_channels) { - __ieee80211_scan_completed(&local->hw, false); - return 1; - } - /* * check if at least one STA interface is associated, * check if at least one STA interface has pending tx frames @@ -535,7 +529,6 @@ static int ieee80211_scan_state_decision(struct ieee80211_local *local, } *next_delay = 0; - return 0; } static void ieee80211_scan_state_leave_oper_channel(struct ieee80211_local *local, @@ -651,7 +644,7 @@ void ieee80211_scan_work(struct work_struct *work) container_of(work, struct ieee80211_local, scan_work.work); struct ieee80211_sub_if_data *sdata = local->scan_sdata; unsigned long next_delay = 0; - bool aborted; + bool aborted, hw_scan, finish; mutex_lock(&local->mtx); @@ -704,8 +697,12 @@ void ieee80211_scan_work(struct work_struct *work) do { switch (local->next_scan_state) { case SCAN_DECISION: - if (ieee80211_scan_state_decision(local, &next_delay)) - return; + /* if no more bands/channels left, complete scan */ + if (local->scan_channel_idx >= local->scan_req->n_channels) { + aborted = false; + goto out_complete; + } + ieee80211_scan_state_decision(local, &next_delay); break; case SCAN_SET_CHANNEL: ieee80211_scan_state_set_channel(local, &next_delay); @@ -726,8 +723,11 @@ void ieee80211_scan_work(struct work_struct *work) return; out_complete: + hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning); + finish = __ieee80211_scan_completed(&local->hw, aborted, hw_scan); mutex_unlock(&local->mtx); - __ieee80211_scan_completed(&local->hw, aborted); + if (finish) + __ieee80211_scan_completed_finish(&local->hw, hw_scan); return; out: @@ -796,6 +796,7 @@ int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata, void ieee80211_scan_cancel(struct ieee80211_local *local) { bool abortscan; + bool finish = false; cancel_delayed_work_sync(&local->scan_work); @@ -806,8 +807,10 @@ void ieee80211_scan_cancel(struct ieee80211_local *local) mutex_lock(&local->mtx); abortscan = test_bit(SCAN_SW_SCANNING, &local->scanning) || (!local->scanning && local->scan_req); + if (abortscan) + finish = __ieee80211_scan_completed(&local->hw, true, false); mutex_unlock(&local->mtx); - if (abortscan) - __ieee80211_scan_completed(&local->hw, true); + if (finish) + __ieee80211_scan_completed_finish(&local->hw, false); }