From: Rafael J. Wysocki rafael.j.wysocki@intel.com
commit e3728b50cd9be7d4b1469447cdf1feb93e3b7adb upstream.
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: 56b991849009 ("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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/acpi/sleep.c | 46 ++++++++++++++++++++++++++++++++-------------- include/linux/suspend.h | 2 +- kernel/power/suspend.c | 9 +++++---- 3 files changed, 38 insertions(+), 19 deletions(-)
--- a/drivers/acpi/sleep.c +++ b/drivers/acpi/sleep.c @@ -987,21 +987,28 @@ 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 IRQD_WAKEUP_ARMED is set for the SCI at this point, the SCI has - * not triggered while suspended, so bail out. - */ - if (!acpi_sci_irq_valid() || - irqd_is_wakeup_armed(irq_get_irq_data(acpi_sci_irq))) - return; - - /* - * If there are EC events to process, the wakeup may be a spurious one - * coming from the EC. - */ - if (acpi_ec_dispatch_gpe()) { + 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 (the + * wakeup is pending anyway and the SCI is not the source of + * it). + */ + if (irqd_is_wakeup_armed(irq_get_irq_data(acpi_sci_irq))) + return true; + + /* + * If there are no EC events to process, the wakeup is regarded + * as a genuine one. + */ + if (!acpi_ec_dispatch_gpe()) + return true; + /* * Cancel the wakeup and process all pending events in case * there are any wakeup ones in there. @@ -1014,8 +1021,19 @@ 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) --- a/include/linux/suspend.h +++ b/include/linux/suspend.h @@ -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); --- a/kernel/power/suspend.c +++ b/kernel/power/suspend.c @@ -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);