PM: s2idle: ACPI: Fix wakeup interrupts handling
authorRafael J. Wysocki <rafael.j.wysocki@intel.com>
Fri, 4 Feb 2022 17:35:22 +0000 (18:35 +0100)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 16 Feb 2022 11:56:19 +0000 (12:56 +0100)
commit0e546bb1324eb7805b96642be16fc34edce41fbd
tree203f4a0ba770082f5ecf102db44f188bcbb1954d
parent65aabd296665f853d9d2805a0c479f99c27a2448
PM: s2idle: ACPI: Fix wakeup interrupts handling

commit cb1f65c1e1424a4b5e4a86da8aa3b8fd8459c8ec upstream.

After commit e3728b50cd9b ("ACPI: PM: s2idle: Avoid possible race
related to the EC GPE") wakeup interrupts occurring immediately after
the one discarded by acpi_s2idle_wake() may be missed.  Moreover, if
the SCI triggers again immediately after the rearming in
acpi_s2idle_wake(), that wakeup may be missed too.

The problem is that pm_system_irq_wakeup() only calls pm_system_wakeup()
when pm_wakeup_irq is 0, but that's not the case any more after the
interrupt causing acpi_s2idle_wake() to run until pm_wakeup_irq is
cleared by the pm_wakeup_clear() call in s2idle_loop().  However,
there may be wakeup interrupts occurring in that time frame and if
that happens, they will be missed.

To address that issue first move the clearing of pm_wakeup_irq to
the point at which it is known that the interrupt causing
acpi_s2idle_wake() to tun will be discarded, before rearming the SCI
for wakeup.  Moreover, because that only reduces the size of the
time window in which the issue may manifest itself, allow
pm_system_irq_wakeup() to register two second wakeup interrupts in
a row and, when discarding the first one, replace it with the second
one.  [Of course, this assumes that only one wakeup interrupt can be
discarded in one go, but currently that is the case and I am not
aware of any plans to change that.]

Fixes: e3728b50cd9b ("ACPI: PM: s2idle: Avoid possible race related to the EC GPE")
Cc: 5.4+ <stable@vger.kernel.org> # 5.4+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/acpi/sleep.c
drivers/base/power/wakeup.c
include/linux/suspend.h
kernel/power/main.c
kernel/power/process.c
kernel/power/suspend.c