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net: watchdog: hold device global xmit lock during tx disable 

commit 3aa6bce9af0e25b735c9c1263739a5639a336ae8 upstream.

Prevent netif_tx_disable() running concurrently with dev_watchdog() by
taking the device global xmit lock. Otherwise, the recommended:

	netif_carrier_off(dev);
	netif_tx_disable(dev);

driver shutdown sequence can happen after the watchdog has already
checked carrier, resulting in possible false alarms. This is because
netif_tx_lock() only sets the frozen bit without maintaining the locks
on the individual queues.

Fixes: c3f26a269c ("netdev: Fix lockdep warnings in multiqueue configurations.")
Signed-off-by: Edwin Peer <edwin.peer@broadcom.com>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Edwin Peer 2021-02-05 17:37:32 -08:00 committed by Greg Kroah-Hartman
parent a5f0b6f7b1
commit 2545c5bd83
1 changed files with 2 additions and 0 deletions
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2
include/linux/netdevice.h
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@ -4044,6 +4044,7 @@ static inline void netif_tx_disable(struct net_device *dev)
local_bh_disable();
cpu = smp_processor_id();
spin_lock(&dev->tx_global_lock);
for (i = 0; i < dev->num_tx_queues; i++) {
struct netdev_queue *txq = netdev_get_tx_queue(dev, i);
@ -4051,6 +4052,7 @@ static inline void netif_tx_disable(struct net_device *dev)
netif_tx_stop_queue(txq);
__netif_tx_unlock(txq);
}
spin_unlock(&dev->tx_global_lock);
local_bh_enable();
}