2 files changed, 39 insertions, 11 deletions

diff --git a/kernel/kmod.c b/kernel/kmod.c
index da7fcca279f9..05698a7415fe 100644
--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -322,7 +322,7 @@ static void __call_usermodehelper(struct work_struct *work)
  * land has been frozen during a system-wide hibernation or suspend operation).
  * Should always be manipulated under umhelper_sem acquired for write.
  */
-static int usermodehelper_disabled = 1;
+static enum umh_disable_depth usermodehelper_disabled = UMH_DISABLED;
 
 /* Number of helpers running */
 static atomic_t running_helpers = ATOMIC_INIT(0);
@@ -347,13 +347,30 @@ static DECLARE_WAIT_QUEUE_HEAD(usermodehelper_disabled_waitq);
 
 int usermodehelper_read_trylock(void)
 {
+	DEFINE_WAIT(wait);
 	int ret = 0;
 
 	down_read(&umhelper_sem);
-	if (usermodehelper_disabled) {
+	for (;;) {
+		prepare_to_wait(&usermodehelper_disabled_waitq, &wait,
+				TASK_INTERRUPTIBLE);
+		if (!usermodehelper_disabled)
+			break;
+
+		if (usermodehelper_disabled == UMH_DISABLED)
+			ret = -EAGAIN;
+
 		up_read(&umhelper_sem);
-		ret = -EAGAIN;
+
+		if (ret)
+			break;
+
+		schedule();
+		try_to_freeze();
+
+		down_read(&umhelper_sem);
 	}
+	finish_wait(&usermodehelper_disabled_waitq, &wait);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(usermodehelper_read_trylock);
@@ -392,25 +409,35 @@ void usermodehelper_read_unlock(void)
 EXPORT_SYMBOL_GPL(usermodehelper_read_unlock);
 
 /**
- * usermodehelper_enable - allow new helpers to be started again
+ * __usermodehelper_set_disable_depth - Modify usermodehelper_disabled.
+ * depth: New value to assign to usermodehelper_disabled.
+ *
+ * Change the value of usermodehelper_disabled (under umhelper_sem locked for
+ * writing) and wakeup tasks waiting for it to change.
  */
-void usermodehelper_enable(void)
+void __usermodehelper_set_disable_depth(enum umh_disable_depth depth)
 {
 	down_write(&umhelper_sem);
-	usermodehelper_disabled = 0;
+	usermodehelper_disabled = depth;
 	wake_up(&usermodehelper_disabled_waitq);
 	up_write(&umhelper_sem);
 }
 
 /**
- * usermodehelper_disable - prevent new helpers from being started
+ * __usermodehelper_disable - Prevent new helpers from being started.
+ * @depth: New value to assign to usermodehelper_disabled.
+ *
+ * Set usermodehelper_disabled to @depth and wait for running helpers to exit.
  */
-int usermodehelper_disable(void)
+int __usermodehelper_disable(enum umh_disable_depth depth)
 {
 	long retval;
 
+	if (!depth)
+		return -EINVAL;
+
 	down_write(&umhelper_sem);
-	usermodehelper_disabled = 1;
+	usermodehelper_disabled = depth;
 	up_write(&umhelper_sem);
 
 	/*
@@ -425,7 +452,7 @@ int usermodehelper_disable(void)
 	if (retval)
 		return 0;
 
-	usermodehelper_enable();
+	__usermodehelper_set_disable_depth(UMH_ENABLED);
 	return -EAGAIN;
 }
 
diff --git a/kernel/power/process.c b/kernel/power/process.c
index 56eaac7e88ab..19db29f67558 100644
--- a/kernel/power/process.c
+++ b/kernel/power/process.c
@@ -123,7 +123,7 @@ int freeze_processes(void)
 {
 	int error;
 
-	error = usermodehelper_disable();
+	error = __usermodehelper_disable(UMH_FREEZING);
 	if (error)
 		return error;
 
@@ -135,6 +135,7 @@ int freeze_processes(void)
 	error = try_to_freeze_tasks(true);
 	if (!error) {
 		printk("done.");
+		__usermodehelper_set_disable_depth(UMH_DISABLED);
 		oom_killer_disable();
 	}
 	printk("\n");