mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/
synced 2026-11-10 20:48:12 +00:00
9e409f1dff
The acpi_battery_get_property() callback calls acpi_battery_get_state()
without any lock held. On some devices, it happens that the property
cache has expired before a uevent reaches userspace, triggering
simultaneous attempts to evaluate _BST. See [1] for an analysis to sysrq
stacktraces on one of the these devices.
In a few cases, including when the AML is sleeping or acquiring a mutex,
ACPICA drops the namespace and interpreter locks and allows the
evaluation of _BST to start while another task is still evaluating it.
This could somehow confuse the interpreter and lead to chaos in AML
mutexes on some devices, see [2] for an example.
Not holding the lock is also prone to race conditions, for example:
CPU0 | CPU1
acpi_battery_get_property() |
acpi_battery_get_state() |
[update_time expired] |
extract_package() | acpi_battery_get_property()
battery->update_time = jiffies | acpi_battery_get_state()
kfree() | [up to date]
| [read capacity_now]
[fix capacity_now due to quirk] |
where CPU1 gets raw capacity_now before CPU0 fixes it to a meaningful
value.
The existing mutex update_lock is not applicapable for
acpi_battery_get_property(), as some code path could call or wait for
acpi_battery_get_property() while holding update_lock.
Therefore, introduce a mutex called property_lock to protect all
accesses to battery properties, so that acpi_battery_get_property() can
take the advantage of the mutex and synchronize itself. With the mutex,
acpi_battery_get_state() are synchronized in all code paths calling it,
and its cache mechanism can always clamp the frequency of _BST
evaluations according to cache_time.
The helper function acpi_battery_handle_discharging() for quirky devices
has to be inlined due to the change, as the mutex must be unlocked
before calling the expensive power_supply_is_system_supplied() helper
function.
Fixes: 86bfd21a0b ("ACPI: battery: Drop redundant locking")
Reported-by: Rick <rickk1166@gmail.com>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=221065#c85 [1]
Reported-by: Avraham Hollander <anhollander516@gmail.com>
Tested-by: Avraham Hollander <anhollander516@gmail.com>
Closes: https://lore.kernel.org/linux-acpi/CAP1mzZReJCn6df5DwEPu-JCQUyr=Pu1cg5xKCMttWZkHCQtVmQ@mail.gmail.com [2]
Signed-off-by: Rong Zhang <i@rong.moe>
Cc: All applicable <stable@vger.kernel.org>
Link: https://patch.msgid.link/20260809-b4-acpi-battery-notification-v5-1-788d54fa2e35@rong.moe
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
1483 lines
41 KiB
1483 lines
41 KiB