Subject: Re: [PATCH NET v3 1/2] net: phy: Add phy loopback support in net phy framework

From: Andrew Lunn <[email-masked]>
Date: Sat, 24 Jun 2017 05:12:31 +0200

> +int phy_loopback(struct phy_device *phydev, bool enable)
> +{
> +	struct phy_driver *phydrv = to_phy_driver(phydev->mdio.dev.driver);
> +	int ret = 0;
> +
> +	if (enable && phydev->loopback_enabled)
> +		return -EBUSY;
> +
> +	if (!enable && !phydev->loopback_enabled)
> +		return -EINVAL;
> +
> +	if (phydev->drv && phydrv->set_loopback)
> +		ret = phydrv->set_loopback(phydev, enable);

   	else
		ret = -EOPNOTSUPP;

> +
> +	if (ret)
> +		return ret;
> +
> +	phydev->loopback_enabled = enable;
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL(phy_loopback);

One of the comments we made of the PHY code in the hns driver is that
its locking is completely broken. You have made the same error
here. The core needs to hold the mutex while calling into the PHY
driver.

	Andrew