Commit c875503a authored by Jijie Shao's avatar Jijie Shao Committed by Jakub Kicinski
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net: hibmcge: fix rtnl deadlock issue 



Currently, the hibmcge netdev acquires the rtnl_lock in
pci_error_handlers.reset_prepare() and releases it in
pci_error_handlers.reset_done().

However, in the PCI framework:
pci_reset_bus - __pci_reset_slot - pci_slot_save_and_disable_locked -
 pci_dev_save_and_disable - err_handler->reset_prepare(dev);

In pci_slot_save_and_disable_locked():
	list_for_each_entry(dev, &slot->bus->devices, bus_list) {
		if (!dev->slot || dev->slot!= slot)
			continue;
		pci_dev_save_and_disable(dev);
		if (dev->subordinate)
			pci_bus_save_and_disable_locked(dev->subordinate);
	}

This will iterate through all devices under the current bus and execute
err_handler->reset_prepare(), causing two devices of the hibmcge driver
to sequentially request the rtnl_lock, leading to a deadlock.

Since the driver now executes netif_device_detach()
before the reset process, it will not concurrently with
other netdev APIs, so there is no need to hold the rtnl_lock now.

Therefore, this patch removes the rtnl_lock during the reset process and
adjusts the position of HBG_NIC_STATE_RESETTING to ensure
that multiple resets are not executed concurrently.

Fixes: 3f5a61f6 ("net: hibmcge: Add reset supported in this module")
Signed-off-by: default avatarJijie Shao <shaojijie@huawei.com>
Reviewed-by: default avatarSimon Horman <horms@kernel.org>
Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent f6a2a310

drivers/net/ethernet/hisilicon/hibmcge/hbg_err.c

+5 −9
Original line number Diff line number Diff line
@@ -53,9 +53,11 @@ static int hbg_reset_prepare(struct hbg_priv *priv, enum hbg_reset_type type) 
{

	int ret;



	ASSERT_RTNL();

	if (test_and_set_bit(HBG_NIC_STATE_RESETTING, &priv->state))

		return -EBUSY;



	if (netif_running(priv->netdev)) {

		clear_bit(HBG_NIC_STATE_RESETTING, &priv->state);

		dev_warn(&priv->pdev->dev,

			 "failed to reset because port is up\n");

		return -EBUSY;
@@ -64,7 +66,6 @@ static int hbg_reset_prepare(struct hbg_priv *priv, enum hbg_reset_type type) 
	netif_device_detach(priv->netdev);



	priv->reset_type = type;

	set_bit(HBG_NIC_STATE_RESETTING, &priv->state);

	clear_bit(HBG_NIC_STATE_RESET_FAIL, &priv->state);

	ret = hbg_hw_event_notify(priv, HBG_HW_EVENT_RESET);

	if (ret) {
@@ -84,29 +85,26 @@ static int hbg_reset_done(struct hbg_priv *priv, enum hbg_reset_type type) 
	    type != priv->reset_type)

		return 0;



	ASSERT_RTNL();



	clear_bit(HBG_NIC_STATE_RESETTING, &priv->state);

	ret = hbg_rebuild(priv);

	if (ret) {

		priv->stats.reset_fail_cnt++;

		set_bit(HBG_NIC_STATE_RESET_FAIL, &priv->state);

		clear_bit(HBG_NIC_STATE_RESETTING, &priv->state);

		dev_err(&priv->pdev->dev, "failed to rebuild after reset\n");

		return ret;

	}



	netif_device_attach(priv->netdev);

	clear_bit(HBG_NIC_STATE_RESETTING, &priv->state);



	dev_info(&priv->pdev->dev, "reset done\n");

	return ret;

}



/* must be protected by rtnl lock */

int hbg_reset(struct hbg_priv *priv)

{

	int ret;



	ASSERT_RTNL();

	ret = hbg_reset_prepare(priv, HBG_RESET_TYPE_FUNCTION);

	if (ret)

		return ret;
@@ -171,7 +169,6 @@ static void hbg_pci_err_reset_prepare(struct pci_dev *pdev) 
	struct net_device *netdev = pci_get_drvdata(pdev);

	struct hbg_priv *priv = netdev_priv(netdev);



	rtnl_lock();

	hbg_reset_prepare(priv, HBG_RESET_TYPE_FLR);

}
@@ -181,7 +178,6 @@ static void hbg_pci_err_reset_done(struct pci_dev *pdev) 
	struct hbg_priv *priv = netdev_priv(netdev);



	hbg_reset_done(priv, HBG_RESET_TYPE_FLR);

	rtnl_unlock();

}



static const struct pci_error_handlers hbg_pci_err_handler = {