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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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af9d8adc6b
If a PCI bridge with an ACPIPHP context attached is removed via
sysfs, the code path executed as a result is the following:
pci_stop_and_remove_bus_device_locked
pci_remove_bus
pcibios_remove_bus
acpi_pci_remove_bus
acpiphp_remove_slots
cleanup_bridge
unregister_hotplug_dock_device (drops dock references to the bridge)
put_bridge
free_bridge
acpiphp_put_context (for each child, under context lock)
kfree (context)
Now, if a dock event affecting one of the bridge's child devices
occurs (roughly at the same time), it will lead to the following code
path:
acpi_dock_deferred_cb
dock_notify
handle_eject_request
hot_remove_dock_devices
dock_hotplug_event
hotplug_event (dereferences context)
That may lead to a kernel crash in hotplug_event() if it is executed
after the last kfree() in the bridge removal code path.
To prevent that from happening, add a wrapper around hotplug_event()
called dock_event() and point the .handler pointer in acpiphp_dock_ops
to it. Make that wrapper retrieve the device's ACPIPHP context using
acpiphp_get_context() (instead of taking it from the data argument)
under acpiphp_context_lock and check if the parent bridge's
is_going_away flag is set. If that flag is set, it will return
immediately and if it is not set it will grab a reference to the
device's parent bridge before executing hotplug_event().
Then, in the above scenario, the reference to the parent bridge
held by dock_event() will prevent free_bridge() from being executed
for it until hotplug_event() returns.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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| .. | ||
| acpi_pcihp.c | ||
| acpiphp_core.c | ||
| acpiphp_glue.c | ||
| acpiphp_ibm.c | ||
| acpiphp.h | ||
| cpci_hotplug_core.c | ||
| cpci_hotplug_pci.c | ||
| cpci_hotplug.h | ||
| cpcihp_generic.c | ||
| cpcihp_zt5550.c | ||
| cpcihp_zt5550.h | ||
| cpqphp_core.c | ||
| cpqphp_ctrl.c | ||
| cpqphp_nvram.c | ||
| cpqphp_nvram.h | ||
| cpqphp_pci.c | ||
| cpqphp_sysfs.c | ||
| cpqphp.h | ||
| ibmphp_core.c | ||
| ibmphp_ebda.c | ||
| ibmphp_hpc.c | ||
| ibmphp_pci.c | ||
| ibmphp_res.c | ||
| ibmphp.h | ||
| Kconfig | ||
| Makefile | ||
| pci_hotplug_core.c | ||
| pciehp_acpi.c | ||
| pciehp_core.c | ||
| pciehp_ctrl.c | ||
| pciehp_hpc.c | ||
| pciehp_pci.c | ||
| pciehp.h | ||
| pcihp_skeleton.c | ||
| pcihp_slot.c | ||
| rpadlpar_core.c | ||
| rpadlpar_sysfs.c | ||
| rpadlpar.h | ||
| rpaphp_core.c | ||
| rpaphp_pci.c | ||
| rpaphp_slot.c | ||
| rpaphp.h | ||
| s390_pci_hpc.c | ||
| sgi_hotplug.c | ||
| shpchp_core.c | ||
| shpchp_ctrl.c | ||
| shpchp_hpc.c | ||
| shpchp_pci.c | ||
| shpchp_sysfs.c | ||
| shpchp.h | ||