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authorRafael J. Wysocki <rafael.j.wysocki@intel.com>2020-02-11 12:11:02 +0300
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2020-02-11 12:11:02 +0300
commite3728b50cd9be7d4b1469447cdf1feb93e3b7adb (patch)
tree446902616310615718c4615e9dbe1a1ea2e5a914 /drivers/acpi/sleep.c
parentf0ac20c3f6137910c8a927953e8a92f5b3716166 (diff)
downloadlinux-e3728b50cd9be7d4b1469447cdf1feb93e3b7adb.tar.xz
ACPI: PM: s2idle: Avoid possible race related to the EC GPE
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>
Diffstat (limited to 'drivers/acpi/sleep.c')
-rw-r--r--drivers/acpi/sleep.c44
1 files changed, 31 insertions, 13 deletions
diff --git a/drivers/acpi/sleep.c b/drivers/acpi/sleep.c
index 439880629839..2c695b196cd2 100644
--- a/drivers/acpi/sleep.c
+++ b/drivers/acpi/sleep.c
@@ -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 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 (!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;
- /*
- * If there are EC events to process, the wakeup may be a spurious one
- * coming from the EC.
- */
- if (acpi_ec_dispatch_gpe()) {
/*
* 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)