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On surprise removal, pciehp_unconfigure_device() and acpiphp's
trim_stale_devices() call pci_dev_set_disconnected() to mark removed
devices as permanently offline. Thereby, the PCI core and drivers know
to skip device accesses.
However pci_dev_set_disconnected() takes the device_lock and thus waits for
a concurrent driver bind or unbind to complete. As a result, the driver's
->probe and ->remove hooks have no chance to learn that the device is gone.
That doesn't make any sense, so drop the device_lock and instead use atomic
xchg() and cmpxchg() operations to update the device state.
As a byproduct, an AB-BA deadlock reported by Anatoli is fixed which occurs
on surprise removal with AER concurrently performing a bus reset.
AER bus reset:
INFO: task irq/26-aerdrv:95 blocked for more than 120 seconds.
Tainted: G W 6.2.0-rc3-custom-norework-jan11+
schedule
rwsem_down_write_slowpath
down_write_nested
pciehp_reset_slot # acquires reset_lock
pci_reset_hotplug_slot
pci_slot_reset # acquires device_lock
pci_bus_error_reset
aer_root_reset
pcie_do_recovery
aer_process_err_devices
aer_isr
pciehp surprise removal:
INFO: task irq/26-pciehp:96 blocked for more than 120 seconds.
Tainted: G W 6.2.0-rc3-custom-norework-jan11+
schedule_preempt_disabled
__mutex_lock
mutex_lock_nested
pci_dev_set_disconnected # acquires device_lock
pci_walk_bus
pciehp_unconfigure_device
pciehp_disable_slot
pciehp_handle_presence_or_link_change
pciehp_ist # acquires reset_lock
Link: https://bugzilla.kernel.org/show_bug.cgi?id=215590
Fixes: a6bd101b8f84 ("PCI: Unify device inaccessible")
Link: https://lore.kernel.org/r/3dc88ea82bdc0e37d9000e413d5ebce481cbd629.1674205689.git.lukas@wunner.de
Reported-by: Anatoli Antonovitch <anatoli.antonovitch@amd.com>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: stable@vger.kernel.org # v4.20+
Cc: Keith Busch <kbusch@kernel.org>
74ff8864cc