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* [PATCH 5.13] mwifiex: bring down link before deleting interface
@ 2021-05-15  2:42 Brian Norris
  2021-05-15 11:36 ` Maximilian Luz
                   ` (3 more replies)
  0 siblings, 4 replies; 10+ messages in thread
From: Brian Norris @ 2021-05-15  2:42 UTC (permalink / raw)
  To: linux-wireless
  Cc: linux-kernel, Ganapathi Bhat, Sharvari Harisangam,
	Amitkumar Karwar, Xinming Hu, Brian Norris, stable,
	Maximilian Luz, dave, Johannes Berg

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>
---
 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();
 	}
 
-- 


^ permalink raw reply related	[flat|nested] 10+ messages in thread

end of thread, other threads:[~2021-06-11 10:04 UTC | newest]

Thread overview: 10+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-05-15  2:42 [PATCH 5.13] mwifiex: bring down link before deleting interface Brian Norris
2021-05-15 11:36 ` Maximilian Luz
2021-05-15 15:10 ` Dave Olsthoorn
2021-05-15 15:40   ` mwifiex firmware crash (Was: Re: [PATCH 5.13] mwifiex: bring down link before deleting interface) Pali Rohár
2021-05-15 16:32     ` mwifiex firmware crash Dave Olsthoorn
2021-05-15 16:53       ` Pali Rohár
2021-05-19 19:20         ` Dave Olsthoorn
2021-06-11  0:18 ` [PATCH 5.13] mwifiex: bring down link before deleting interface Brian Norris
2021-06-11  9:53   ` Kalle Valo
2021-06-11 10:03 ` Kalle Valo

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