[PATCH 5.12 194/242] mwifiex: bring down link before deleting interface

Greg Kroah-Hartman
2021-07-15T19:18:19Z

From: Brian Norris <briannorris@chromium.org>

commit 1f9482aa8d412b4ba06ce6ab8e333fb8ca29a06e upstream.

We can deadlock when rmmod'ing the driver or going through firmware
reset, because the cfg80211_unregister_wdev() has to bring down the link
for us, ... which then grab the same wiphy lock.

nl80211_del_interface() already handles a very similar case, with a nice
description:

/*
* We hold RTNL, so this is safe, without RTNL opencount cannot
* reach 0, and thus the rdev cannot be deleted.
*
* We need to do it for the dev_close(), since that will call
* the netdev notifiers, and we need to acquire the mutex there
* but don't know if we get there from here or from some other
* place (e.g. "ip link set ... down").
*/
mutex_unlock(&rdev->wiphy.mtx);
...

Do similarly for mwifiex teardown, by ensuring we bring the link down
first.

Sample deadlock trace:

[ 247.103516] INFO: task rmmod:2119 blocked for more than 123 seconds.
[ 247.110630] Not tainted 5.12.4 #5
[ 247.115796] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 247.124557] task:rmmod state:D stack: 0 pid: 2119 ppid: 2114 flags:0x00400208
[ 247.133905] Call trace:
[ 247.136644] __switch_to+0x130/0x170
[ 247.140643] __schedule+0x714/0xa0c
[ 247.144548] schedule_preempt_disabled+0x88/0xf4
[ 247.149714] __mutex_lock_common+0x43c/0x750
[ 247.154496] mutex_lock_nested+0x5c/0x68
[ 247.158884] cfg80211_netdev_notifier_call+0x280/0x4e0 [cfg80211]
[ 247.165769] raw_notifier_call_chain+0x4c/0x78
[ 247.170742] call_netdevice_notifiers_info+0x68/0xa4
[ 247.176305] __dev_close_many+0x7c/0x138
[ 247.180693] dev_close_many+0x7c/0x10c
[ 247.184893] unregister_netdevice_many+0xfc/0x654
[ 247.190158] unregister_netdevice_queue+0xb4/0xe0
[ 247.195424] _cfg80211_unregister_wdev+0xa4/0x204 [cfg80211]
[ 247.201816] cfg80211_unregister_wdev+0x20/0x2c [cfg80211]
[ 247.208016] mwifiex_del_virtual_intf+0xc8/0x188 [mwifiex]
[ 247.214174] mwifiex_uninit_sw+0x158/0x1b0 [mwifiex]
[ 247.219747] mwifiex_remove_card+0x38/0xa0 [mwifiex]
[ 247.225316] mwifiex_pcie_remove+0xd0/0xe0 [mwifiex_pcie]
[ 247.231451] pci_device_remove+0x50/0xe0
[ 247.235849] device_release_driver_internal+0x110/0x1b0
[ 247.241701] driver_detach+0x5c/0x9c
[ 247.245704] bus_remove_driver+0x84/0xb8
[ 247.250095] driver_unregister+0x3c/0x60
[ 247.254486] pci_unregister_driver+0x2c/0x90
[ 247.259267] cleanup_module+0x18/0xcdc [mwifiex_pcie]

Fixes: a05829a7222e ("cfg80211: avoid holding the RTNL when calling the driver")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/linux-wireless/98392296-40ee-6300-369c-32e16cff3725@gmail.com/
Link: https://lore.kernel.org/linux-wireless/ab4d00ce52f32bd8e45ad0448a44737e@bewaar.me/
Reported-by: Maximilian Luz <luzmaximilian@gmail.com>
Reported-by: dave@bewaar.me
Cc: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Brian Norris <briannorris@chromium.org>
Tested-by: Maximilian Luz <luzmaximilian@gmail.com>
Tested-by: Dave Olsthoorn <dave@bewaar.me>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210515024227.2159311-1-briannorris@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/net/wireless/marvell/mwifiex/main.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)

--- a/drivers/net/wireless/marvell/mwifiex/main.c
+++ b/drivers/net/wireless/marvell/mwifiex/main.c
@@ -1445,11 +1445,18 @@ static void mwifiex_uninit_sw(struct mwi
if (!priv)
continue;
rtnl_lock();
- wiphy_lock(adapter->wiphy);
if (priv->netdev &&
- priv->wdev.iftype != NL80211_IFTYPE_UNSPECIFIED)
+ priv->wdev.iftype != NL80211_IFTYPE_UNSPECIFIED) {
+ /*
+ * Close the netdev now, because if we do it later, the
+ * netdev notifiers will need to acquire the wiphy lock
+ * again --> deadlock.
+ */
+ dev_close(priv->wdev.netdev);
+ wiphy_lock(adapter->wiphy);
mwifiex_del_virtual_intf(adapter->wiphy, &priv->wdev);
- wiphy_unlock(adapter->wiphy);
+ wiphy_unlock(adapter->wiphy);
+ }
rtnl_unlock();
}