Re: [PATCH 5.10 06/41] net: pxa168_eth: Fix a potential data race in pxa168_eth_remove

[Pavel Machek]

Hi!

> [ Upstream commit 0571a753cb07982cc82f4a5115e0b321da89e1f3 ]
> 
> pxa168_eth_remove() firstly calls unregister_netdev(),
> then cancels a timeout work. unregister_netdev() shuts down a device
> interface and removes it from the kernel tables. If the timeout occurs
> in parallel, the timeout work (pxa168_eth_tx_timeout_task) performs stop
> and open of the device. It may lead to an inconsistent state and memory
> leaks.

AFAICT the timeout work does a lot of processing, including
pxa168_eth_open(), pxa168_init_phy() and phy_connect_direct(). We
probably don't want that to run with clock being disabled and DMA
being unmapped.

We certainly don't want phy_disconnect() being undone by
phy_connect_direct() running in the workqueue.

IOW this patch is not enough to fix the bugs, and at least fix below
is needed to get something reasonable.

Signed-off-by: Pavel Machek (CIP) <pa...@denx.de>

Best regards,
                                                                Pavel

> +++ b/drivers/net/ethernet/marvell/pxa168_eth.c
> @@ -1544,8 +1544,8 @@ static int pxa168_eth_remove(struct platform_device 
> *pdev)
>       clk_disable_unprepare(pep->clk);
>       mdiobus_unregister(pep->smi_bus);
>       mdiobus_free(pep->smi_bus);
> -     unregister_netdev(dev);
>       cancel_work_sync(&pep->tx_timeout_task);
> +     unregister_netdev(dev);
>       free_netdev(dev);
>       return 0;
>  }

diff --git a/drivers/net/ethernet/marvell/pxa168_eth.c 
b/drivers/net/ethernet/marvell/pxa168_eth.c
index d1e4d42e497d..432be22a51be 100644
--- a/drivers/net/ethernet/marvell/pxa168_eth.c
+++ b/drivers/net/ethernet/marvell/pxa168_eth.c
@@ -1532,7 +1532,8 @@ static int pxa168_eth_remove(struct platform_device *pdev)
 {
        struct net_device *dev = platform_get_drvdata(pdev);
        struct pxa168_eth_private *pep = netdev_priv(dev);
-
+       
+       cancel_work_sync(&pep->tx_timeout_task);
        if (pep->htpr) {
                dma_free_coherent(pep->dev->dev.parent, HASH_ADDR_TABLE_SIZE,
                                  pep->htpr, pep->htpr_dma);
@@ -1545,7 +1546,6 @@ static int pxa168_eth_remove(struct platform_device *pdev)
        mdiobus_unregister(pep->smi_bus);
        mdiobus_free(pep->smi_bus);
        unregister_netdev(dev);
-       cancel_work_sync(&pep->tx_timeout_task);
        free_netdev(dev);
        return 0;
 }

-- 
DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany

signature.asc
Description: Digital signature