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ACPI / SBS: Fix rare oops when removing modules

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[ Upstream commit 757c968c442397f1249bb775a7c8c03842e3e0c7 ]

There was a small race when removing the sbshc module where
smbus_alarm() had queued acpi_smbus_callback() for deferred execution
but it hadn't been run yet, so that when it did run hc had been freed
and the module unloaded, resulting in an invalid paging request.

A similar race existed when removing the sbs module with regards to
acpi_sbs_callback() (which is called from acpi_smbus_callback()).

We therefore need to ensure no callbacks are pending or executing before
the cleanups are done and the modules are removed.

Signed-off-by: Ronald Tschalär <ronald@innovation.ch>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Ronald Tschalär 2018-09-30 19:53:13 -07:00 committed by Greg Kroah-Hartman
parent 7f02606367
commit d43b7b99fe
2 changed files with 3 additions and 0 deletions
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1
drivers/acpi/osl.c
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@ -1132,6 +1132,7 @@ void acpi_os_wait_events_complete(void)
flush_workqueue(kacpid_wq);
flush_workqueue(kacpi_notify_wq);
}
EXPORT_SYMBOL(acpi_os_wait_events_complete);
struct acpi_hp_work {
struct work_struct work;

2
drivers/acpi/sbshc.c
View file

@ -196,6 +196,7 @@ int acpi_smbus_unregister_callback(struct acpi_smb_hc *hc)
hc->callback = NULL;
hc->context = NULL;
mutex_unlock(&hc->lock);
acpi_os_wait_events_complete();
return 0;
}
@ -292,6 +293,7 @@ static int acpi_smbus_hc_remove(struct acpi_device *device)
hc = acpi_driver_data(device);
acpi_ec_remove_query_handler(hc->ec, hc->query_bit);
acpi_os_wait_events_complete();
kfree(hc);
device->driver_data = NULL;
return 0;