On 2021-05-15 04:42, Brian Norris wrote:

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@... Link: https://lore.kernel.org/linux-wireless/ab4d00ce52f32bd8e45ad0448a44737e@bewa... Reported-by: Maximilian Luz luzmaximilian@gmail.com Reported-by: Dave Olsthoorn dave@bewaar.me

Thanks!

The firmware still seems to crash quicker than previously, but that's a unrelated problem.

Tested-by: Dave Olsthoorn dave@bewaar.me

Cc: Johannes Berg johannes@sipsolutions.net Signed-off-by: Brian Norris briannorris@chromium.org

---

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

diff --git a/drivers/net/wireless/marvell/mwifiex/main.c b/drivers/net/wireless/marvell/mwifiex/main.c index 529dfd8b7ae8..17399d4aa129 100644 --- 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 mwifiex_adapter *adapter) 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(); }