linux-kernel - [PATCH] PM: suspend: Fix platform_suspend_prepare

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Date:   Sat, 10 Aug 2019 13:24:04 +0200
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Linux PM <linux-pm@...r.kernel.org>
Cc:     Marek Szyprowski <m.szyprowski@...sung.com>,
        Linux ACPI <linux-acpi@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Zhang Rui <rui.zhang@...el.com>,
        Rajneesh Bhardwaj <rajneesh.bhardwaj@...ux.intel.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Mario Limonciello <mario.limonciello@...l.com>,
        Kai-Heng Feng <kai.heng.feng@...onical.com>
Subject: [PATCH] PM: suspend: Fix platform_suspend_prepare_noirq()

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

After commit ac9eafbe930a ("ACPI: PM: s2idle: Execute LPS0 _DSM
functions with suspended devices"), a NULL pointer may be dereferenced
if suspend-to-idle is attempted on a platform without "traditional"
suspend support due to invalid fall-through in
platform_suspend_prepare_noirq().

Fix that and while at it add missing braces in platform_resume_noirq().

Fixes: ac9eafbe930a ("ACPI: PM: s2idle: Execute LPS0 _DSM functions with suspended devices")
Reported-by: Marek Szyprowski <m.szyprowski@...sung.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---

Commit ac9eafbe930a is in linux-next only at this point.

---
 kernel/power/suspend.c |   11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

Index: linux-pm/kernel/power/suspend.c
===================================================================
--- linux-pm.orig/kernel/power/suspend.c
+++ linux-pm/kernel/power/suspend.c
@@ -253,10 +253,10 @@ static int platform_suspend_prepare_late
 
 static int platform_suspend_prepare_noirq(suspend_state_t state)
 {
-	if (state == PM_SUSPEND_TO_IDLE) {
-		if (s2idle_ops && s2idle_ops->prepare_late)
-			return s2idle_ops->prepare_late();
-	}
+	if (state == PM_SUSPEND_TO_IDLE)
+		return s2idle_ops && s2idle_ops->prepare_late ?
+			s2idle_ops->prepare_late() : 0;
+
 	return suspend_ops->prepare_late ? suspend_ops->prepare_late() : 0;
 }
 
@@ -265,8 +265,9 @@ static void platform_resume_noirq(suspen
 	if (state == PM_SUSPEND_TO_IDLE) {
 		if (s2idle_ops && s2idle_ops->restore_early)
 			s2idle_ops->restore_early();
-	} else if (suspend_ops->wake)
+	} else if (suspend_ops->wake) {
 		suspend_ops->wake();
+	}
 }
 
 static void platform_resume_early(suspend_state_t state)