The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 1758bde2e4aa5ff188d53e7d9d388bbb7e12eebb Mon Sep 17 00:00:00 2001 From: Lukas Wunner lukas@wunner.de Date: Tue, 28 Jun 2022 12:15:08 +0200 Subject: [PATCH] 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 1ce8b37241ed ("usbnet: smsc95xx: Forward PHY interrupts to PHY driver to avoid polling"), but has existed since forever.

Fixes: 541cd3ee00a4 ("phylib: Fix deadlock on resume") Link: https://lore.kernel.org/netdev/a5315a8a-32c2-962f-f696-de9a26d30091@samsung.... Reported-by: Marek Szyprowski m.szyprowski@samsung.com Tested-by: Marek Szyprowski m.szyprowski@samsung.com Signed-off-by: Lukas Wunner lukas@wunner.de Acked-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Cc: stable@vger.kernel.org # v2.6.33+ Reviewed-by: Andrew Lunn andrew@lunn.ch Link: https://lore.kernel.org/r/b7f386d04e9b5b0e2738f0125743e30676f309ef.165641089... Signed-off-by: Jakub Kicinski kuba@kernel.org

diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c index ef62f357b76d..8d3ee3a6495b 100644 --- a/drivers/net/phy/phy.c +++ b/drivers/net/phy/phy.c @@ -31,6 +31,7 @@ #include <linux/io.h> #include <linux/uaccess.h> #include <linux/atomic.h> +#include <linux/suspend.h> #include <net/netlink.h> #include <net/genetlink.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; 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); ret = drv->handle_interrupt(phydev); mutex_unlock(&phydev->lock); diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c index 431a8719c635..46acddd865a7 100644 --- a/drivers/net/phy/phy_device.c +++ b/drivers/net/phy/phy_device.c @@ -278,6 +278,15 @@ static __maybe_unused int mdio_bus_phy_suspend(struct device *dev) if (phydev->mac_managed_pm) 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 * control, possibly with the phydev->lock held. Upon resume, netdev * 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) return ret; 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) phy_start_machine(phydev);

diff --git a/include/linux/phy.h b/include/linux/phy.h index 508f1149665b..b09f7d36cff2 100644 --- a/include/linux/phy.h +++ b/include/linux/phy.h @@ -572,6 +572,10 @@ struct macsec_ops; * @mdix_ctrl: User setting of crossover * @pma_extable: Cached value of PMA/PMD Extended Abilities Register * @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 * @skb: Netlink message for cable diagnostics * @nest: Netlink nest used for cable diagnostics @@ -626,6 +630,8 @@ struct phy_device {

/* Interrupts are enabled */ unsigned interrupts:1; + unsigned irq_suspended:1; + unsigned irq_rerun:1;

enum phy_state state;