netdev - Re: [PATCH net-next v3 5/7] usbnet: smsc95xx: Forward PHY interrupts to PHY driver to avoid polling

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <2f612dd0-ac30-4860-ef1b-bbb180da21af@samsung.com>
Date:   Tue, 24 May 2022 08:16:23 +0200
From:   Marek Szyprowski <m.szyprowski@...sung.com>
To:     Andrew Lunn <andrew@...n.ch>, Lukas Wunner <lukas@...ner.de>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Eric Dumazet <edumazet@...gle.com>, netdev@...r.kernel.org,
        linux-usb@...r.kernel.org,
        Steve Glendinning <steve.glendinning@...well.net>,
        UNGLinuxDriver@...rochip.com, Oliver Neukum <oneukum@...e.com>,
        Andre Edich <andre.edich@...rochip.com>,
        Oleksij Rempel <linux@...pel-privat.de>,
        Martyn Welch <martyn.welch@...labora.com>,
        Gabriel Hojda <ghojda@...urs.ro>,
        Christoph Fritz <chf.fritz@...glemail.com>,
        Lino Sanfilippo <LinoSanfilippo@....de>,
        Philipp Rosenberger <p.rosenberger@...bus.com>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Russell King <linux@...linux.org.uk>,
        Ferry Toth <fntoth@...il.com>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        'Linux Samsung SOC' <linux-samsung-soc@...r.kernel.org>
Subject: Re: [PATCH net-next v3 5/7] usbnet: smsc95xx: Forward PHY
 interrupts to PHY driver to avoid polling

On 24.05.2022 03:08, Andrew Lunn wrote:
>> @@ -976,6 +977,25 @@ static irqreturn_t phy_interrupt(int irq, void *phy_dat)
>>   	struct phy_driver *drv = phydev->drv;
>>   	irqreturn_t ret;
>>   
>> +	if (IS_ENABLED(CONFIG_PM_SLEEP) &&
>> +	    (phydev->mdio.dev.power.is_prepared ||
>> +	     phydev->mdio.dev.power.is_suspended)) {
>> +		struct net_device *netdev = phydev->attached_dev;
>> +
>> +		if (netdev) {
>> +			struct device *parent = netdev->dev.parent;
>> +
>> +			if (netdev->wol_enabled)
>> +				pm_system_wakeup();
>> +			else if (device_may_wakeup(&netdev->dev))
>> +				pm_wakeup_dev_event(&netdev->dev, 0, true);
>> +			else if (parent && device_may_wakeup(parent))
>> +				pm_wakeup_dev_event(parent, 0, true);
>> +		}
>> +
>> +		return IRQ_HANDLED;
> I'm not sure you can just throw the interrupt away. There have been
> issues with WoL, where the WoL signal has been applied to a PMC, not
> an actual interrupt. Yet the PHY driver assumes it is an
> interrupt. And in order for WoL to work correctly, it needs the
> interrupt handler to be called. We said the hardware is broken, WoL
> cannot work for that setup.
>
> Here you have correct hardware, but you are throwing the interrupt
> away, which will have the same result. So i think you need to abort
> the suspend, get the bus working again, and call the interrupt
> handler. If this is a WoL interrupt you are supposed to be waking up
> anyway.

This hardware doesn't support wake-on-lan. It looks somehow that it 
manages to throw an interrupt just a moment before the power regulator 
for the whole usb bus is cut off.

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland