linux-kernel - [PATCH 2/2] ACPI: PM: s2idle: Prevent spurious SCIs from waking up the system

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Date:   Tue, 11 Feb 2020 17:53:52 +0100
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Linux ACPI <linux-acpi@...r.kernel.org>
Cc:     Linux PM <linux-pm@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Zhang Rui <rui.zhang@...el.com>,
        David Box <david.e.box@...ux.intel.com>,
        Chen Yu <yu.c.chen@...el.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Tsuchiya Yuto <kitakar@...il.com>,
        Bob Moore <robert.moore@...el.com>,
        Erik Kaneda <erik.kaneda@...el.com>
Subject: [PATCH 2/2] ACPI: PM: s2idle: Prevent spurious SCIs from waking up the system

From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

If the platform triggers a spurious SCI even though the status bit
is not set for any GPE when the system is suspended to idle, it will
be treated as a genuine wakeup, so avoid that by checking if any GPEs
are active at all before returning 'true' from acpi_s2idle_wake().

Link: https://bugzilla.kernel.org/show_bug.cgi?id=206413
Fixes: 56b991849009 ("PM: sleep: Simplify suspend-to-idle control flow")
Reported-by: Tsuchiya Yuto <kitakar@...il.com>
Cc: 5.4+ <stable@...r.kernel.org> # 5.4+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
 drivers/acpi/sleep.c |   12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

Index: linux-pm/drivers/acpi/sleep.c
===================================================================
--- linux-pm.orig/drivers/acpi/sleep.c
+++ linux-pm/drivers/acpi/sleep.c
@@ -1006,10 +1006,16 @@ static bool acpi_s2idle_wake(void)
 			return true;
 
 		/*
-		 * If there are no EC events to process, the wakeup is regarded
-		 * as a genuine one.
+		 * If there are no EC events to process and at least one of the
+		 * other enabled GPEs is active, the wakeup is regarded as a
+		 * genuine one.
+		 *
+		 * Note that the checks below must be carried out in this order
+		 * to avoid returning prematurely due to a change of the EC GPE
+		 * status bit from unset to set between the checks with the
+		 * status bits of all the other GPEs unset.
 		 */
-		if (!acpi_ec_dispatch_gpe())
+		if (acpi_any_gpe_status_set() && !acpi_ec_dispatch_gpe())
 			return true;
 
 		/*