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

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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 1ce8b37241 ("usbnet: smsc95xx: Forward
PHY interrupts to PHY driver to avoid polling"), but has existed since
forever.

Fixes: 541cd3ee00 ("phylib: Fix deadlock on resume")
Link: https://lore.kernel.org/netdev/a5315a8a-32c2-962f-f696-de9a26d30091@samsung.com/
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.1656410895.git.lukas@wunner.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Lukas Wunner
2022-06-28 12:15:08 +02:00
committed by Jakub Kicinski
parent e65af5403e
commit 1758bde2e4
3 changed files with 52 additions and 0 deletions
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6
include/linux/phy.h
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@@ -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;