From 7b9643c970c77db6ab8cc7760b7e2cc2e4daface Mon Sep 17 00:00:00 2001
From: "Rafael J. Wysocki" <rjw@sisk.pl>
Date: Wed, 28 Mar 2012 23:30:21 +0200
Subject: [PATCH] PM / Sleep: Move disabling of usermode helpers to the freezer

commit 1e73203cd1157a03facc41ffb54050f5b28e55bd upstream.

The core suspend/hibernation code calls usermodehelper_disable() to
avoid race conditions between the freezer and the starting of
usermode helpers and each code path has to do that on its own.
However, it is always called right before freeze_processes()
and usermodehelper_enable() is always called right after
thaw_processes().  For this reason, to avoid code duplication and
to make the connection between usermodehelper_disable() and the
freezer more visible, make freeze_processes() call it and remove the
direct usermodehelper_disable() and usermodehelper_enable() calls
from all suspend/hibernation code paths.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 kernel/power/hibernate.c | 11 -----------
 kernel/power/process.c   |  7 +++++++
 kernel/power/suspend.c   |  7 -------
 kernel/power/user.c      | 10 +---------
 4 files changed, 8 insertions(+), 27 deletions(-)

diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index 12334ee412c..a364144ad33 100644
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -16,7 +16,6 @@
 #include <linux/string.h>
 #include <linux/device.h>
 #include <linux/async.h>
-#include <linux/kmod.h>
 #include <linux/delay.h>
 #include <linux/fs.h>
 #include <linux/mount.h>
@@ -618,10 +617,6 @@ int hibernate(void)
 	sys_sync();
 	printk("done.\n");
 
-	error = usermodehelper_disable();
-	if (error)
-		goto Exit;
-
 	error = freeze_processes();
 	if (error)
 		goto Free_bitmaps;
@@ -658,7 +653,6 @@ int hibernate(void)
  Thaw:
 	thaw_processes();
  Free_bitmaps:
-	usermodehelper_enable();
 	free_basic_memory_bitmaps();
  Exit:
 	pm_notifier_call_chain(PM_POST_HIBERNATION);
@@ -778,10 +772,6 @@ static int software_resume(void)
 	if (error)
 		goto close_finish;
 
-	error = usermodehelper_disable();
-	if (error)
-		goto close_finish;
-
 	pr_debug("PM: Preparing processes for restore.\n");
 	error = freeze_processes();
 	if (error) {
@@ -800,7 +790,6 @@ static int software_resume(void)
 	swsusp_free();
 	thaw_processes();
  Done:
-	usermodehelper_enable();
 	free_basic_memory_bitmaps();
  Finish:
 	pm_notifier_call_chain(PM_POST_RESTORE);
diff --git a/kernel/power/process.c b/kernel/power/process.c
index 7e426459e60..0d20bc0455d 100644
--- a/kernel/power/process.c
+++ b/kernel/power/process.c
@@ -16,6 +16,7 @@
 #include <linux/freezer.h>
 #include <linux/delay.h>
 #include <linux/workqueue.h>
+#include <linux/kmod.h>
 
 /* 
  * Timeout for stopping processes
@@ -122,6 +123,10 @@ int freeze_processes(void)
 {
 	int error;
 
+	error = usermodehelper_disable();
+	if (error)
+		return error;
+
 	if (!pm_freezing)
 		atomic_inc(&system_freezing_cnt);
 
@@ -187,6 +192,8 @@ void thaw_processes(void)
 	} while_each_thread(g, p);
 	read_unlock(&tasklist_lock);
 
+	usermodehelper_enable();
+
 	schedule();
 	printk("done.\n");
 }
diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c
index 4fd51beed87..038d72bc59f 100644
--- a/kernel/power/suspend.c
+++ b/kernel/power/suspend.c
@@ -12,7 +12,6 @@
 #include <linux/delay.h>
 #include <linux/errno.h>
 #include <linux/init.h>
-#include <linux/kmod.h>
 #include <linux/console.h>
 #include <linux/cpu.h>
 #include <linux/syscalls.h>
@@ -101,17 +100,12 @@ static int suspend_prepare(void)
 	if (error)
 		goto Finish;
 
-	error = usermodehelper_disable();
-	if (error)
-		goto Finish;
-
 	error = suspend_freeze_processes();
 	if (!error)
 		return 0;
 
 	suspend_stats.failed_freeze++;
 	dpm_save_failed_step(SUSPEND_FREEZE);
-	usermodehelper_enable();
  Finish:
 	pm_notifier_call_chain(PM_POST_SUSPEND);
 	pm_restore_console();
@@ -259,7 +253,6 @@ int suspend_devices_and_enter(suspend_state_t state)
 static void suspend_finish(void)
 {
 	suspend_thaw_processes();
-	usermodehelper_enable();
 	pm_notifier_call_chain(PM_POST_SUSPEND);
 	pm_restore_console();
 }
diff --git a/kernel/power/user.c b/kernel/power/user.c
index 3e100075b13..89dc7e45254 100644
--- a/kernel/power/user.c
+++ b/kernel/power/user.c
@@ -12,7 +12,6 @@
 #include <linux/suspend.h>
 #include <linux/syscalls.h>
 #include <linux/reboot.h>
-#include <linux/kmod.h>
 #include <linux/string.h>
 #include <linux/device.h>
 #include <linux/miscdevice.h>
@@ -222,14 +221,8 @@ static long snapshot_ioctl(struct file *filp, unsigned int cmd,
 		sys_sync();
 		printk("done.\n");
 
-		error = usermodehelper_disable();
-		if (error)
-			break;
-
 		error = freeze_processes();
-		if (error)
-			usermodehelper_enable();
-		else
+		if (!error)
 			data->frozen = 1;
 		break;
 
@@ -238,7 +231,6 @@ static long snapshot_ioctl(struct file *filp, unsigned int cmd,
 			break;
 		pm_restore_gfp_mask();
 		thaw_processes();
-		usermodehelper_enable();
 		data->frozen = 0;
 		break;
 
-- 
2.11.4.GIT