2021-01-28 00:30:57

by Johannes Berg

[permalink] [raw]
Subject: [PATCH] virt_wifi: fix deadlock on RTNL

From: Johannes Berg <[email protected]>

Fix a regression where everything in virt_wifi would just hang. This
happened due to overlapping changes between commit a05829a7222e
("cfg80211: avoid holding the RTNL when calling the driver") which
had originally needed to change the locking, but then I introduced
commit 2fe8ef106238 ("cfg80211: change netdev registration/unregistration
semantics") instead. virt_wifi somehow fell through the cracks when
I undid all the previous locking changes. Fix it now.

Fixes: a05829a7222e ("cfg80211: avoid holding the RTNL when calling the driver")
Signed-off-by: Johannes Berg <[email protected]>
---
drivers/net/wireless/virt_wifi.c | 8 --------
1 file changed, 8 deletions(-)

diff --git a/drivers/net/wireless/virt_wifi.c b/drivers/net/wireless/virt_wifi.c
index 4b455a4ae15b..c878097f0dda 100644
--- a/drivers/net/wireless/virt_wifi.c
+++ b/drivers/net/wireless/virt_wifi.c
@@ -537,9 +537,7 @@ static int virt_wifi_newlink(struct net *src_net, struct net_device *dev,
dev->ieee80211_ptr->iftype = NL80211_IFTYPE_STATION;
dev->ieee80211_ptr->wiphy = common_wiphy;

- wiphy_lock(common_wiphy);
err = register_netdevice(dev);
- wiphy_unlock(common_wiphy);
if (err) {
dev_err(&priv->lowerdev->dev, "can't register_netdevice: %d\n",
err);
@@ -562,9 +560,7 @@ static int virt_wifi_newlink(struct net *src_net, struct net_device *dev,

return 0;
unregister_netdev:
- wiphy_lock(common_wiphy);
unregister_netdevice(dev);
- wiphy_unlock(common_wiphy);
free_wireless_dev:
kfree(dev->ieee80211_ptr);
dev->ieee80211_ptr = NULL;
@@ -590,9 +586,7 @@ static void virt_wifi_dellink(struct net_device *dev,
netdev_rx_handler_unregister(priv->lowerdev);
netdev_upper_dev_unlink(priv->lowerdev, dev);

- wiphy_lock(common_wiphy);
unregister_netdevice_queue(dev, head);
- wiphy_unlock(common_wiphy);
module_put(THIS_MODULE);

/* Deleting the wiphy is handled in the module destructor. */
@@ -631,9 +625,7 @@ static int virt_wifi_event(struct notifier_block *this, unsigned long event,
upper_dev = priv->upperdev;

upper_dev->rtnl_link_ops->dellink(upper_dev, &list_kill);
- wiphy_lock(common_wiphy);
unregister_netdevice_many(&list_kill);
- wiphy_unlock(common_wiphy);
break;
}

--
2.26.2