Re: [PATCH net v1] lan78xx: Fix crash with multiple device attach

Paolo Abeni
2024-05-06T09:38:34Z

On Thu, 2024-05-02 at 10:27 +0530, Rengarajan S wrote:
> After the first device(MAC + PHY) is attached, the corresponding
> fixup gets registered and before it is unregistered next device
> is attached causing the dev pointer of second device to be NULL.
> Fixed the issue with multiple PHY attach by unregistering PHY
> at the end of probe. Removed the unregistration during phy_init
> since the handling has been taken care in probe.

The above description is unclear to me. Could you please list the exact
sequence of events/calls that lead to the problem?

> Fixes: 89b36fb5e532 ("lan78xx: Lan7801 Support for Fixed PHY")
> Signed-off-by: Rengarajan S <rengarajan.s@microchip.com>
> ---
>
> drivers/net/usb/lan78xx.c | 16 +++++++++-------
> 1 file changed, 9 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/net/usb/lan78xx.c b/drivers/net/usb/lan78xx.c
> index 5add4145d..3ec79620f 100644
> --- a/drivers/net/usb/lan78xx.c
> +++ b/drivers/net/usb/lan78xx.c
> @@ -2383,14 +2383,8 @@ static int lan78xx_phy_init(struct lan78xx_net *dev)
> netdev_err(dev->net, "can't attach PHY to %s\n",
> dev->mdiobus->id);
> if (dev->chipid == ID_REV_CHIP_ID_7801_) {
> - if (phy_is_pseudo_fixed_link(phydev)) {
> + if (phy_is_pseudo_fixed_link(phydev))
> fixed_phy_unregister(phydev);
> - } else {
> - phy_unregister_fixup_for_uid(PHY_KSZ9031RNX,
> - 0xfffffff0);
> - phy_unregister_fixup_for_uid(PHY_LAN8835,
> - 0xfffffff0);
> - }
> }
> return -EIO;
> }
> @@ -4458,6 +4452,14 @@ static int lan78xx_probe(struct usb_interface *intf,
> pm_runtime_set_autosuspend_delay(&udev->dev,
> DEFAULT_AUTOSUSPEND_DELAY);
>
> + /* Unregistering Fixup to avoid crash with multiple device
> + * attach.
> + */
> + phy_unregister_fixup_for_uid(PHY_KSZ9031RNX,
> + 0xfffffff0);
> + phy_unregister_fixup_for_uid(PHY_LAN8835,
> + 0xfffffff0);
> +

Minor nit: the above 2 statments can now fit a single line each.

Thanks,

Paolo