mt76: fix schedule while atomic in mt76x02_reset_state

Fix following schedule while atomic in mt76x02_reset_state
since synchronize_rcu is run inside a RCU section

[44036.944222] mt76x2e 0000:06:00.0: MCU message 31 (seq 3) timed out
[44036.944281] BUG: sleeping function called from invalid context at kernel/rcu/tree_exp.h:818
[44036.944284] in_atomic(): 1, irqs_disabled(): 0, pid: 28066, name: kworker/u4:1
[44036.944287] INFO: lockdep is turned off.
[44036.944292] CPU: 1 PID: 28066 Comm: kworker/u4:1 Tainted: G        W         5.0.0-rc7-wdn-t1+ #7
[44036.944294] Hardware name: Dell Inc. Studio XPS 1340/0K183D, BIOS A11 09/08/2009
[44036.944305] Workqueue: phy1 mt76x02_wdt_work [mt76x02_lib]
[44036.944308] Call Trace:
[44036.944317]  dump_stack+0x67/0x90
[44036.944322]  ___might_sleep.cold.88+0x9f/0xaf
[44036.944327]  rcu_blocking_is_gp+0x13/0x50
[44036.944330]  synchronize_rcu+0x17/0x80
[44036.944337]  mt76_sta_state+0x138/0x1d0 [mt76]
[44036.944349]  mt76x02_wdt_work+0x1c9/0x610 [mt76x02_lib]
[44036.944355]  process_one_work+0x2a5/0x620
[44036.944361]  worker_thread+0x35/0x3e0
[44036.944368]  kthread+0x11c/0x140
[44036.944376]  ret_from_fork+0x3a/0x50
[44036.944384] BUG: scheduling while atomic: kworker/u4:1/28066/0x00000002
[44036.944387] INFO: lockdep is turned off.
[44036.944389] Modules linked in: cmac ctr ccm af_packet snd_hda_codec_hdmi

Introduce __mt76_sta_remove in order to run sta_remove without holding dev->mutex.
Move __mt76_sta_remove outside of RCU section in mt76x02_reset_state

Fixes: e4ebb8b403d1 ("mt76: mt76x2: implement full device restart on watchdog reset")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

diff --git a/drivers/net/wireless/mediatek/mt76/mac80211.c b/drivers/net/wireless/mediatek/mt76/mac80211.c
index a033745..3161674 100644 (file)
--- a/drivers/net/wireless/mediatek/mt76/mac80211.c
+++ b/drivers/net/wireless/mediatek/mt76/mac80211.c
@@ -679,19 +679,15 @@ out:
        return ret;
 }
 
-static void
-mt76_sta_remove(struct mt76_dev *dev, struct ieee80211_vif *vif,
-               struct ieee80211_sta *sta)
+void __mt76_sta_remove(struct mt76_dev *dev, struct ieee80211_vif *vif,
+                      struct ieee80211_sta *sta)
 {
        struct mt76_wcid *wcid = (struct mt76_wcid *)sta->drv_priv;
-       int idx = wcid->idx;
-       int i;
+       int i, idx = wcid->idx;
 
        rcu_assign_pointer(dev->wcid[idx], NULL);
        synchronize_rcu();
 
-       mutex_lock(&dev->mutex);
-
        if (dev->drv->sta_remove)
                dev->drv->sta_remove(dev, vif, sta);
 
@@ -699,7 +695,15 @@ mt76_sta_remove(struct mt76_dev *dev, struct ieee80211_vif *vif,
        for (i = 0; i < ARRAY_SIZE(sta->txq); i++)
                mt76_txq_remove(dev, sta->txq[i]);
        mt76_wcid_free(dev->wcid_mask, idx);
+}
+EXPORT_SYMBOL_GPL(__mt76_sta_remove);
 
+static void
+mt76_sta_remove(struct mt76_dev *dev, struct ieee80211_vif *vif,
+               struct ieee80211_sta *sta)
+{
+       mutex_lock(&dev->mutex);
+       __mt76_sta_remove(dev, vif, sta);
        mutex_unlock(&dev->mutex);
 }
 

diff --git a/drivers/net/wireless/mediatek/mt76/mt76.h b/drivers/net/wireless/mediatek/mt76/mt76.h
index cb50e96..bcbfd3c 100644 (file)
--- a/drivers/net/wireless/mediatek/mt76/mt76.h
+++ b/drivers/net/wireless/mediatek/mt76/mt76.h
@@ -695,6 +695,8 @@ int mt76_sta_state(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
                   struct ieee80211_sta *sta,
                   enum ieee80211_sta_state old_state,
                   enum ieee80211_sta_state new_state);
+void __mt76_sta_remove(struct mt76_dev *dev, struct ieee80211_vif *vif,
+                      struct ieee80211_sta *sta);
 
 struct ieee80211_sta *mt76_rx_convert(struct sk_buff *skb);
 

diff --git a/drivers/net/wireless/mediatek/mt76/mt76x02_mmio.c b/drivers/net/wireless/mediatek/mt76/mt76x02_mmio.c
index 9de015b..daaed12 100644 (file)
--- a/drivers/net/wireless/mediatek/mt76/mt76x02_mmio.c
+++ b/drivers/net/wireless/mediatek/mt76/mt76x02_mmio.c
@@ -441,19 +441,23 @@ static void mt76x02_reset_state(struct mt76x02_dev *dev)
 {
        int i;
 
+       lockdep_assert_held(&dev->mt76.mutex);
+
        clear_bit(MT76_STATE_RUNNING, &dev->mt76.state);
 
        rcu_read_lock();
-
        ieee80211_iter_keys_rcu(dev->mt76.hw, NULL, mt76x02_key_sync, NULL);
+       rcu_read_unlock();
 
        for (i = 0; i < ARRAY_SIZE(dev->mt76.wcid); i++) {
-               struct mt76_wcid *wcid = rcu_dereference(dev->mt76.wcid[i]);
-               struct mt76x02_sta *msta;
                struct ieee80211_sta *sta;
                struct ieee80211_vif *vif;
+               struct mt76x02_sta *msta;
+               struct mt76_wcid *wcid;
                void *priv;
 
+               wcid = rcu_dereference_protected(dev->mt76.wcid[i],
+                                       lockdep_is_held(&dev->mt76.mutex));
                if (!wcid)
                        continue;
 
@@ -463,13 +467,10 @@ static void mt76x02_reset_state(struct mt76x02_dev *dev)
                priv = msta->vif;
                vif = container_of(priv, struct ieee80211_vif, drv_priv);
 
-               mt76_sta_state(dev->mt76.hw, vif, sta,
-                              IEEE80211_STA_NONE, IEEE80211_STA_NOTEXIST);
+               __mt76_sta_remove(&dev->mt76, vif, sta);
                memset(msta, 0, sizeof(*msta));
        }
 
-       rcu_read_unlock();
-
        dev->vif_mask = 0;
        dev->beacon_mask = 0;
 }
@@ -489,11 +490,11 @@ static void mt76x02_watchdog_reset(struct mt76x02_dev *dev)
        for (i = 0; i < ARRAY_SIZE(dev->mt76.napi); i++)
                napi_disable(&dev->mt76.napi[i]);
 
+       mutex_lock(&dev->mt76.mutex);
+
        if (restart)
                mt76x02_reset_state(dev);
 
-       mutex_lock(&dev->mt76.mutex);
-
        if (dev->beacon_mask)
                mt76_clear(dev, MT_BEACON_TIME_CFG,
                           MT_BEACON_TIME_CFG_BEACON_TX |