netdev - Re: [PATCH net] net: phy: Restore phy

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Message-ID: <48d13be9-8351-14e4-8fc9-feb1452b88a7@huawei.com>
Date:   Mon, 26 Feb 2018 10:09:26 +0800
From:   Yunsheng Lin <linyunsheng@...wei.com>
To:     Andrew Lunn <andrew@...n.ch>, David Miller <davem@...emloft.net>
CC:     <hkallweit1@...il.com>, Florian Fainelli <f.fainelli@...il.com>,
        netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH net] net: phy: Restore phy_resume() locking assumption

Hi, Andrew

On 2018/2/26 7:04, Lunn wrote:
> commit f5e64032a799 ("net: phy: fix resume handling") changes the
> locking semantics for phy_resume() such that the caller now needs to
> hold the phy mutex. Not all call sites were adopted to this new
> semantic, resulting in warnings from the added
> WARN_ON(!mutex_is_locked(&phydev->lock)).  Rather than change the
> semantics, add a __phy_resume() and restore the old behavior of
> phy_resume().
> 
> Reported-by: Heiner Kallweit <hkallweit1@...il.com>
> Fixes: f5e64032a799 ("net: phy: fix resume handling")
> Signed-off-by: Andrew Lunn <andrew@...n.ch>
> ---
>  drivers/net/phy/phy.c        |  2 +-
>  drivers/net/phy/phy_device.c | 18 +++++++++++++-----
>  include/linux/phy.h          |  1 +
>  3 files changed, 15 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
> index e3e29c2b028b..a6f924fee584 100644
> --- a/drivers/net/phy/phy.c
> +++ b/drivers/net/phy/phy.c
> @@ -819,7 +819,7 @@ void phy_start(struct phy_device *phydev)
>  		break;
>  	case PHY_HALTED:
>  		/* if phy was suspended, bring the physical link up again */
> -		phy_resume(phydev);
> +		__phy_resume(phydev);
>  
>  		/* make sure interrupts are re-enabled for the PHY */
>  		if (phy_interrupt_is_valid(phydev)) {
> diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
> index d39ae77707ef..4cfb3851ed1f 100644
> --- a/drivers/net/phy/phy_device.c
> +++ b/drivers/net/phy/phy_device.c
> @@ -135,9 +135,7 @@ static int mdio_bus_phy_resume(struct device *dev)
>  	if (!mdio_bus_phy_may_suspend(phydev))
>  		goto no_resume;
>  
> -	mutex_lock(&phydev->lock);
>  	ret = phy_resume(phydev);
> -	mutex_unlock(&phydev->lock);
>  	if (ret < 0)
>  		return ret;
>  
> @@ -1041,9 +1039,7 @@ int phy_attach_direct(struct net_device *dev, struct phy_device *phydev,
>  	if (err)
>  		goto error;
>  
> -	mutex_lock(&phydev->lock);
>  	phy_resume(phydev);
> -	mutex_unlock(&phydev->lock);
>  	phy_led_triggers_register(phydev);
>  
>  	return err;
> @@ -1172,7 +1168,7 @@ int phy_suspend(struct phy_device *phydev)
>  }
>  EXPORT_SYMBOL(phy_suspend);
>  
> -int phy_resume(struct phy_device *phydev)
> +int __phy_resume(struct phy_device *phydev)
>  {
>  	struct phy_driver *phydrv = to_phy_driver(phydev->mdio.dev.driver);
>  	int ret = 0;
> @@ -1189,6 +1185,18 @@ int phy_resume(struct phy_device *phydev)
>  
>  	return ret;
>  }
> +EXPORT_SYMBOL(__phy_resume);
> +
> +int phy_resume(struct phy_device *phydev)
> +{
> +	int ret;
> +
> +	mutex_lock(&phydev->lock);
> +	ret = phy_resume(phydev);

phy_resume -> __phy_resume?

> +	mutex_unlock(&phydev->lock);
> +
> +	return ret;
> +}
>  EXPORT_SYMBOL(phy_resume);
>  
>  int phy_loopback(struct phy_device *phydev, bool enable)
> diff --git a/include/linux/phy.h b/include/linux/phy.h
> index 5a0c3e53e7c2..d7069539f351 100644
> --- a/include/linux/phy.h
> +++ b/include/linux/phy.h
> @@ -924,6 +924,7 @@ void phy_device_remove(struct phy_device *phydev);
>  int phy_init_hw(struct phy_device *phydev);
>  int phy_suspend(struct phy_device *phydev);
>  int phy_resume(struct phy_device *phydev);
> +int __phy_resume(struct phy_device *phydev);
>  int phy_loopback(struct phy_device *phydev, bool enable);
>  struct phy_device *phy_attach(struct net_device *dev, const char *bus_id,
>  			      phy_interface_t interface);
>