cfg80211: avoid holding the RTNL when calling the driver

Currently, _everything_ in cfg80211 holds the RTNL, and if you
have a slow USB device (or a few) you can get some bad lock
contention on that.

Fix that by re-adding a mutex to each wiphy/rdev as we had at
some point, so we have locking for the wireless_dev lists and
all the other things in there, and also so that drivers still
don't have to worry too much about it (they still won't get
parallel calls for a single device).

Then, we can restrict the RTNL to a few cases where we add or
remove interfaces and really need the added protection. Some
of the global list management still also uses the RTNL, since
we need to have it anyway for netdev management, but we only
hold the RTNL for very short periods of time here.

Link: https://lore.kernel.org/r/20210122161942.81df9f5e047a.I4a8e1a60b18863ea8c5e6d3a0faeafb2d45b2f40@changeid
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com> [marvell driver issues]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

6 files changed, 17 insertions, 2 deletions

diff --git a/drivers/net/wireless/ath/ath11k/reg.c b/drivers/net/wireless/ath/ath11k/reg.c
index b876fec7fa1b..e1a1df169034 100644
--- a/drivers/net/wireless/ath/ath11k/reg.c
+++ b/drivers/net/wireless/ath/ath11k/reg.c
@@ -247,7 +247,9 @@ int ath11k_regd_update(struct ath11k *ar, bool init)
 	}
 
 	rtnl_lock();
-	ret = regulatory_set_wiphy_regd_sync_rtnl(ar->hw->wiphy, regd_copy);
+	wiphy_lock(ar->hw->wiphy);
+	ret = regulatory_set_wiphy_regd_sync(ar->hw->wiphy, regd_copy);
+	wiphy_unlock(ar->hw->wiphy);
 	rtnl_unlock();
 
 	kfree(regd_copy);
diff --git a/drivers/net/wireless/ath/ath6kl/core.c b/drivers/net/wireless/ath/ath6kl/core.c
index ebb9f163710f..4f0a7a185fc9 100644
--- a/drivers/net/wireless/ath/ath6kl/core.c
+++ b/drivers/net/wireless/ath/ath6kl/core.c
@@ -212,11 +212,13 @@ int ath6kl_core_init(struct ath6kl *ar, enum ath6kl_htc_type htc_type)
 		ar->avail_idx_map |= BIT(i);
 
 	rtnl_lock();
+	wiphy_lock(ar->wiphy);
 
 	/* Add an initial station interface */
 	wdev = ath6kl_interface_add(ar, "wlan%d", NET_NAME_ENUM,
 				    NL80211_IFTYPE_STATION, 0, INFRA_NETWORK);
 
+	wiphy_unlock(ar->wiphy);
 	rtnl_unlock();
 
 	if (!wdev) {
diff --git a/drivers/net/wireless/ath/ath6kl/init.c b/drivers/net/wireless/ath/ath6kl/init.c
index 39bf19686175..9b5c7d8f2b95 100644
--- a/drivers/net/wireless/ath/ath6kl/init.c
+++ b/drivers/net/wireless/ath/ath6kl/init.c
@@ -1904,7 +1904,9 @@ void ath6kl_stop_txrx(struct ath6kl *ar)
 		spin_unlock_bh(&ar->list_lock);
 		ath6kl_cfg80211_vif_stop(vif, test_bit(WMI_READY, &ar->flag));
 		rtnl_lock();
+		wiphy_lock(ar->wiphy);
 		ath6kl_cfg80211_vif_cleanup(vif);
+		wiphy_unlock(ar->wiphy);
 		rtnl_unlock();
 		spin_lock_bh(&ar->list_lock);
 	}
diff --git a/drivers/net/wireless/ath/wil6210/cfg80211.c b/drivers/net/wireless/ath/wil6210/cfg80211.c
index 1c42410d68e1..60bba5b491e0 100644
--- a/drivers/net/wireless/ath/wil6210/cfg80211.c
+++ b/drivers/net/wireless/ath/wil6210/cfg80211.c
@@ -2820,7 +2820,9 @@ void wil_p2p_wdev_free(struct wil6210_priv *wil)
 	wil->radio_wdev = wil->main_ndev->ieee80211_ptr;
 	mutex_unlock(&wil->vif_mutex);
 	if (p2p_wdev) {
+		wiphy_lock(wil->wiphy);
 		cfg80211_unregister_wdev(p2p_wdev);
+		wiphy_unlock(wil->wiphy);
 		kfree(p2p_wdev);
 	}
 }
diff --git a/drivers/net/wireless/ath/wil6210/netdev.c b/drivers/net/wireless/ath/wil6210/netdev.c
index 472fe804203d..0913f0bf60e7 100644
--- a/drivers/net/wireless/ath/wil6210/netdev.c
+++ b/drivers/net/wireless/ath/wil6210/netdev.c
@@ -473,7 +473,9 @@ int wil_if_add(struct wil6210_priv *wil)
 	wil_update_net_queues_bh(wil, vif, NULL, true);
 
 	rtnl_lock();
+	wiphy_lock(wiphy);
 	rc = wil_vif_add(wil, vif);
+	wiphy_unlock(wiphy);
 	rtnl_unlock();
 	if (rc < 0)
 		goto out_wiphy;
@@ -543,15 +545,18 @@ void wil_if_remove(struct wil6210_priv *wil)
 {
 	struct net_device *ndev = wil->main_ndev;
 	struct wireless_dev *wdev = ndev->ieee80211_ptr;
+	struct wiphy *wiphy = wdev->wiphy;
 
 	wil_dbg_misc(wil, "if_remove\n");
 
 	rtnl_lock();
+	wiphy_lock(wiphy);
 	wil_vif_remove(wil, 0);
+	wiphy_unlock(wiphy);
 	rtnl_unlock();
 
 	netif_napi_del(&wil->napi_tx);
 	netif_napi_del(&wil->napi_rx);
 
-	wiphy_unregister(wdev->wiphy);
+	wiphy_unregister(wiphy);
 }
diff --git a/drivers/net/wireless/ath/wil6210/pcie_bus.c b/drivers/net/wireless/ath/wil6210/pcie_bus.c
index c174323c5c0b..ce40d94909ad 100644
--- a/drivers/net/wireless/ath/wil6210/pcie_bus.c
+++ b/drivers/net/wireless/ath/wil6210/pcie_bus.c
@@ -473,8 +473,10 @@ static void wil_pcie_remove(struct pci_dev *pdev)
 
 	wil6210_debugfs_remove(wil);
 	rtnl_lock();
+	wiphy_lock(wil->wiphy);
 	wil_p2p_wdev_free(wil);
 	wil_remove_all_additional_vifs(wil);
+	wiphy_unlock(wil->wiphy);
 	rtnl_unlock();
 	wil_if_remove(wil);
 	wil_if_pcie_disable(wil);