Commit 1758bde2 authored by Lukas Wunner's avatar Lukas Wunner Committed by Jakub Kicinski
Browse files

net: phy: Don't trigger state machine while in suspend 

Upon system sleep, mdio_bus_phy_suspend() stops the phy_state_machine(),
but subsequent interrupts may retrigger it:

They may have been left enabled to facilitate wakeup and are not
quiesced until the ->suspend_noirq() phase.  Unwanted interrupts may
hence occur between mdio_bus_phy_suspend() and dpm_suspend_noirq(),
as well as between dpm_resume_noirq() and mdio_bus_phy_resume().

Retriggering the phy_state_machine() through an interrupt is not only
undesirable for the reason given in mdio_bus_phy_suspend() (freezing it
midway with phydev->lock held), but also because the PHY may be
inaccessible after it's suspended:  Accesses to USB-attached PHYs are
blocked once usb_suspend_both() clears the can_submit flag and PHYs on
PCI network cards may become inaccessible upon suspend as well.

Amend phy_interrupt() to avoid triggering the state machine if the PHY
is suspended.  Signal wakeup instead if the attached net_device or its
parent has been configured as a wakeup source.  (Those conditions are
identical to mdio_bus_phy_may_suspend().)  Postpone handling of the
interrupt until the PHY has resumed.

Before stopping the phy_state_machine() in mdio_bus_phy_suspend(),
wait for a concurrent phy_interrupt() to run to completion.  That is
necessary because phy_interrupt() may have checked the PHY's suspend
status before the system sleep transition commenced and it may thus
retrigger the state machine after it was stopped.

Likewise, after re-enabling interrupt handling in mdio_bus_phy_resume(),
wait for a concurrent phy_interrupt() to complete to ensure that
interrupts which it postponed are properly rerun.

The issue was exposed by commit 1ce8b372 ("usbnet: smsc95xx: Forward
PHY interrupts to PHY driver to avoid polling"), but has existed since
forever.

Fixes: 541cd3ee ("phylib: Fix deadlock on resume")
Link: https://lore.kernel.org/netdev/a5315a8a-32c2-962f-f696-de9a26d30091@samsung.com/


Reported-by: default avatarMarek Szyprowski <m.szyprowski@samsung.com>
Tested-by: default avatarMarek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: default avatarLukas Wunner <lukas@wunner.de>
Acked-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: stable@vger.kernel.org # v2.6.33+
Reviewed-by: default avatarAndrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/b7f386d04e9b5b0e2738f0125743e30676f309ef.1656410895.git.lukas@wunner.de


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent e65af540

drivers/net/phy/phy.c

+23 −0
Original line number Original line Diff line number Diff line
@@ -31,6 +31,7 @@ 
#include <linux/io.h>

#include <linux/io.h>

#include <linux/uaccess.h>

#include <linux/uaccess.h>

#include <linux/atomic.h>

#include <linux/atomic.h>

#include <linux/suspend.h>

#include <net/netlink.h>

#include <net/netlink.h>

#include <net/genetlink.h>

#include <net/genetlink.h>

#include <net/sock.h>

#include <net/sock.h>
@@ -976,6 +977,28 @@ static irqreturn_t phy_interrupt(int irq, void *phy_dat) 
	struct phy_driver *drv = phydev->drv;

	struct phy_driver *drv = phydev->drv;

	irqreturn_t ret;

	irqreturn_t ret;





	/* Wakeup interrupts may occur during a system sleep transition.

	 * Postpone handling until the PHY has resumed.

	 */

	if (IS_ENABLED(CONFIG_PM_SLEEP) && phydev->irq_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);

		}



		phydev->irq_rerun = 1;

		disable_irq_nosync(irq);

		return IRQ_HANDLED;

	}



	mutex_lock(&phydev->lock);

	mutex_lock(&phydev->lock);

	ret = drv->handle_interrupt(phydev);

	ret = drv->handle_interrupt(phydev);

	mutex_unlock(&phydev->lock);

	mutex_unlock(&phydev->lock);

drivers/net/phy/phy_device.c

+23 −0
Original line number Original line Diff line number Diff line
@@ -278,6 +278,15 @@ static __maybe_unused int mdio_bus_phy_suspend(struct device *dev) 
	if (phydev->mac_managed_pm)

	if (phydev->mac_managed_pm)

		return 0;

		return 0;





	/* Wakeup interrupts may occur during the system sleep transition when

	 * the PHY is inaccessible. Set flag to postpone handling until the PHY

	 * has resumed. Wait for concurrent interrupt handler to complete.

	 */

	if (phy_interrupt_is_valid(phydev)) {

		phydev->irq_suspended = 1;

		synchronize_irq(phydev->irq);

	}



	/* We must stop the state machine manually, otherwise it stops out of

	/* We must stop the state machine manually, otherwise it stops out of

	 * control, possibly with the phydev->lock held. Upon resume, netdev

	 * control, possibly with the phydev->lock held. Upon resume, netdev

	 * may call phy routines that try to grab the same lock, and that may

	 * may call phy routines that try to grab the same lock, and that may
@@ -315,6 +324,20 @@ static __maybe_unused int mdio_bus_phy_resume(struct device *dev) 
	if (ret < 0)

	if (ret < 0)

		return ret;

		return ret;

no_resume:

no_resume:

	if (phy_interrupt_is_valid(phydev)) {

		phydev->irq_suspended = 0;

		synchronize_irq(phydev->irq);



		/* Rerun interrupts which were postponed by phy_interrupt()

		 * because they occurred during the system sleep transition.

		 */

		if (phydev->irq_rerun) {

			phydev->irq_rerun = 0;

			enable_irq(phydev->irq);

			irq_wake_thread(phydev->irq, phydev);

		}

	}



	if (phydev->attached_dev && phydev->adjust_link)

	if (phydev->attached_dev && phydev->adjust_link)

		phy_start_machine(phydev);

		phy_start_machine(phydev);

include/linux/phy.h

+6 −0
Original line number Original line Diff line number Diff line
@@ -572,6 +572,10 @@ struct macsec_ops; 
 * @mdix_ctrl: User setting of crossover

 * @mdix_ctrl: User setting of crossover

 * @pma_extable: Cached value of PMA/PMD Extended Abilities Register

 * @pma_extable: Cached value of PMA/PMD Extended Abilities Register

 * @interrupts: Flag interrupts have been enabled

 * @interrupts: Flag interrupts have been enabled

 * @irq_suspended: Flag indicating PHY is suspended and therefore interrupt

 *                 handling shall be postponed until PHY has resumed

 * @irq_rerun: Flag indicating interrupts occurred while PHY was suspended,

 *             requiring a rerun of the interrupt handler after resume

 * @interface: enum phy_interface_t value

 * @interface: enum phy_interface_t value

 * @skb: Netlink message for cable diagnostics

 * @skb: Netlink message for cable diagnostics

 * @nest: Netlink nest used for cable diagnostics

 * @nest: Netlink nest used for cable diagnostics
@@ -626,6 +630,8 @@ struct phy_device { 




	/* Interrupts are enabled */

	/* Interrupts are enabled */

	unsigned interrupts:1;

	unsigned interrupts:1;

	unsigned irq_suspended:1;

	unsigned irq_rerun:1;





	enum phy_state state;

	enum phy_state state;