netdev - [PATCH net 5/5] e1000: Move cancel_work

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Message-ID: <20250610171348.1476574-6-anthony.l.nguyen@intel.com>
Date: Tue, 10 Jun 2025 10:13:45 -0700
From: Tony Nguyen <anthony.l.nguyen@...el.com>
To: davem@...emloft.net,
	kuba@...nel.org,
	pabeni@...hat.com,
	edumazet@...gle.com,
	andrew+netdev@...n.ch,
	netdev@...r.kernel.org
Cc: Joe Damato <jdamato@...tly.com>,
	anthony.l.nguyen@...el.com,
	stfomichev@...il.com,
	syzbot+846bb38dc67fe62cc733@...kaller.appspotmail.com,
	John <john.cs.hey@...il.com>,
	Stanislav Fomichev <sdf@...ichev.me>,
	Jacob Keller <jacob.e.keller@...el.com>
Subject: [PATCH net 5/5] e1000: Move cancel_work_sync to avoid deadlock

From: Joe Damato <jdamato@...tly.com>

Previously, e1000_down called cancel_work_sync for the e1000 reset task
(via e1000_down_and_stop), which takes RTNL.

As reported by users and syzbot, a deadlock is possible in the following
scenario:

CPU 0:
  - RTNL is held
  - e1000_close
  - e1000_down
  - cancel_work_sync (cancel / wait for e1000_reset_task())

CPU 1:
  - process_one_work
  - e1000_reset_task
  - take RTNL

To remedy this, avoid calling cancel_work_sync from e1000_down
(e1000_reset_task does nothing if the device is down anyway). Instead,
call cancel_work_sync for e1000_reset_task when the device is being
removed.

Fixes: e400c7444d84 ("e1000: Hold RTNL when e1000_down can be called")
Reported-by: syzbot+846bb38dc67fe62cc733@...kaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/683837bf.a00a0220.52848.0003.GAE@google.com/
Reported-by: John <john.cs.hey@...il.com>
Closes: https://lore.kernel.org/netdev/CAP=Rh=OEsn4y_2LvkO3UtDWurKcGPnZ_NPSXK=FbgygNXL37Sw@mail.gmail.com/
Signed-off-by: Joe Damato <jdamato@...tly.com>
Acked-by: Stanislav Fomichev <sdf@...ichev.me>
Acked-by: Jacob Keller <jacob.e.keller@...el.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@...el.com>
---
 drivers/net/ethernet/intel/e1000/e1000_main.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/intel/e1000/e1000_main.c b/drivers/net/ethernet/intel/e1000/e1000_main.c
index 3f089c3d47b2..d8595e84326d 100644
--- a/drivers/net/ethernet/intel/e1000/e1000_main.c
+++ b/drivers/net/ethernet/intel/e1000/e1000_main.c
@@ -477,10 +477,6 @@ static void e1000_down_and_stop(struct e1000_adapter *adapter)
 
 	cancel_delayed_work_sync(&adapter->phy_info_task);
 	cancel_delayed_work_sync(&adapter->fifo_stall_task);
-
-	/* Only kill reset task if adapter is not resetting */
-	if (!test_bit(__E1000_RESETTING, &adapter->flags))
-		cancel_work_sync(&adapter->reset_task);
 }
 
 void e1000_down(struct e1000_adapter *adapter)
@@ -1266,6 +1262,10 @@ static void e1000_remove(struct pci_dev *pdev)
 
 	unregister_netdev(netdev);
 
+	/* Only kill reset task if adapter is not resetting */
+	if (!test_bit(__E1000_RESETTING, &adapter->flags))
+		cancel_work_sync(&adapter->reset_task);
+
 	e1000_phy_hw_reset(hw);
 
 	kfree(adapter->tx_ring);
-- 
2.47.1