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ACPI: PM: s2idle: Avoid possible race related to the EC GPE

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It is theoretically possible for the ACPI EC GPE to be set after the
s2idle_ops->wake() called from s2idle_loop() has returned and before
the subsequent pm_wakeup_pending() check is carried out.  If that
happens, the resulting wakeup event will cause the system to resume
even though it may be a spurious one.

To avoid that race, first make the ->wake() callback in struct
platform_s2idle_ops return a bool value indicating whether or not
to let the system resume and rearrange s2idle_loop() to use that
value instad of the direct pm_wakeup_pending() call if ->wake() is
present.

Next, rework acpi_s2idle_wake() to process EC events and check
pm_wakeup_pending() before re-arming the SCI for system wakeup
to prevent it from triggering prematurely and add comments to
that function to explain the rationale for the new code flow.

Fixes: 56b9918490 ("PM: sleep: Simplify suspend-to-idle control flow")
Cc: 5.4+ <stable@vger.kernel.org> # 5.4+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Rafael J. Wysocki 2020-02-11 10:11:02 +01:00
parent f0ac20c3f6
commit e3728b50cd
3 changed files with 37 additions and 18 deletions
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36
drivers/acpi/sleep.c
View File

@ -990,21 +990,28 @@ static void acpi_s2idle_sync(void)
acpi_os_wait_events_complete(); /* synchronize Notify handling */
}
static void acpi_s2idle_wake(void)
static bool acpi_s2idle_wake(void)
{
if (!acpi_sci_irq_valid())
return pm_wakeup_pending();
while (pm_wakeup_pending()) {
/*
* If IRQD_WAKEUP_ARMED is set for the SCI at this point, the SCI has
* not triggered while suspended, so bail out.
* If IRQD_WAKEUP_ARMED is set for the SCI at this point, the
* SCI has not triggered while suspended, so bail out (the
* wakeup is pending anyway and the SCI is not the source of
* it).
*/
if (!acpi_sci_irq_valid() ||
irqd_is_wakeup_armed(irq_get_irq_data(acpi_sci_irq)))
return;
if (irqd_is_wakeup_armed(irq_get_irq_data(acpi_sci_irq)))
return true;
/*
* If there are EC events to process, the wakeup may be a spurious one
* coming from the EC.
* If there are no EC events to process, the wakeup is regarded
* as a genuine one.
*/
if (acpi_ec_dispatch_gpe()) {
if (!acpi_ec_dispatch_gpe())
return true;
/*
* Cancel the wakeup and process all pending events in case
* there are any wakeup ones in there.
@ -1017,8 +1024,19 @@ static void acpi_s2idle_wake(void)
acpi_s2idle_sync();
/*
* The SCI is in the "suspended" state now and it cannot produce
* new wakeup events till the rearming below, so if any of them
* are pending here, they must be resulting from the processing
* of EC events above or coming from somewhere else.
*/
if (pm_wakeup_pending())
return true;
rearm_wake_irq(acpi_sci_irq);
}
return false;
}
static void acpi_s2idle_restore_early(void)

2
include/linux/suspend.h
View File

@ -191,7 +191,7 @@ struct platform_s2idle_ops {
int (*begin)(void);
int (*prepare)(void);
int (*prepare_late)(void);
void (*wake)(void);
bool (*wake)(void);
void (*restore_early)(void);
void (*restore)(void);
void (*end)(void);

9
kernel/power/suspend.c
View File

@ -131,11 +131,12 @@ static void s2idle_loop(void)
* to avoid them upfront.
*/
for (;;) {
if (s2idle_ops && s2idle_ops->wake)
s2idle_ops->wake();
if (pm_wakeup_pending())
if (s2idle_ops && s2idle_ops->wake) {
if (s2idle_ops->wake())
break;
} else if (pm_wakeup_pending()) {
break;
}
pm_wakeup_clear(false);