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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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9
kernel/power/suspend.c
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@@ -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);