Merge branch 'pm-sleep' into pm-for-linus

* pm-sleep: (51 commits)
  PM: Drop generic_subsys_pm_ops
  PM / Sleep: Remove forward-only callbacks from AMBA bus type
  PM / Sleep: Remove forward-only callbacks from platform bus type
  PM: Run the driver callback directly if the subsystem one is not there
  PM / Sleep: Make pm_op() and pm_noirq_op() return callback pointers
  PM / Sleep: Merge internal functions in generic_ops.c
  PM / Sleep: Simplify generic system suspend callbacks
  PM / Hibernate: Remove deprecated hibernation snapshot ioctls
  PM / Sleep: Fix freezer failures due to racy usermodehelper_is_disabled()
  PM / Sleep: Recommend [un]lock_system_sleep() over using pm_mutex directly
  PM / Sleep: Replace mutex_[un]lock(&pm_mutex) with [un]lock_system_sleep()
  PM / Sleep: Make [un]lock_system_sleep() generic
  PM / Sleep: Use the freezer_count() functions in [un]lock_system_sleep() APIs
  PM / Freezer: Remove the "userspace only" constraint from freezer[_do_not]_count()
  PM / Hibernate: Replace unintuitive 'if' condition in kernel/power/user.c with 'else'
  Freezer / sunrpc / NFS: don't allow TASK_KILLABLE sleeps to block the freezer
  PM / Sleep: Unify diagnostic messages from device suspend/resume
  ACPI / PM: Do not save/restore NVS on Asus K54C/K54HR
  PM / Hibernate: Remove deprecated hibernation test modes
  PM / Hibernate: Thaw processes in SNAPSHOT_CREATE_IMAGE ioctl test path
  ...

Conflicts:
	kernel/kmod.c

1 files changed, 24 insertions, 1 deletions

diff --git a/kernel/kmod.c b/kernel/kmod.c
index 2142687094d..a0a88543934 100644
--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -34,6 +34,9 @@
 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/resource.h>
+#include <linux/notifier.h>
+#include <linux/suspend.h>
+#include <linux/rwsem.h>
 #include <asm/uaccess.h>
 
 #include <trace/events/module.h>
@@ -48,6 +51,7 @@ static struct workqueue_struct *khelper_wq;
 static kernel_cap_t usermodehelper_bset = CAP_FULL_SET;
 static kernel_cap_t usermodehelper_inheritable = CAP_FULL_SET;
 static DEFINE_SPINLOCK(umh_sysctl_lock);
+static DECLARE_RWSEM(umhelper_sem);
 
 #ifdef CONFIG_MODULES
 
@@ -273,6 +277,7 @@ static void __call_usermodehelper(struct work_struct *work)
  * If set, call_usermodehelper_exec() will exit immediately returning -EBUSY
  * (used for preventing user land processes from being created after the user
  * 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;
 
@@ -291,6 +296,18 @@ static DECLARE_WAIT_QUEUE_HEAD(running_helpers_waitq);
  */
 #define RUNNING_HELPERS_TIMEOUT	(5 * HZ)
 
+void read_lock_usermodehelper(void)
+{
+	down_read(&umhelper_sem);
+}
+EXPORT_SYMBOL_GPL(read_lock_usermodehelper);
+
+void read_unlock_usermodehelper(void)
+{
+	up_read(&umhelper_sem);
+}
+EXPORT_SYMBOL_GPL(read_unlock_usermodehelper);
+
 /**
  * usermodehelper_disable - prevent new helpers from being started
  */
@@ -298,8 +315,10 @@ int usermodehelper_disable(void)
 {
 	long retval;
 
+	down_write(&umhelper_sem);
 	usermodehelper_disabled = 1;
-	smp_mb();
+	up_write(&umhelper_sem);
+
 	/*
 	 * From now on call_usermodehelper_exec() won't start any new
 	 * helpers, so it is sufficient if running_helpers turns out to
@@ -312,7 +331,9 @@ int usermodehelper_disable(void)
 	if (retval)
 		return 0;
 
+	down_write(&umhelper_sem);
 	usermodehelper_disabled = 0;
+	up_write(&umhelper_sem);
 	return -EAGAIN;
 }
 
@@ -321,7 +342,9 @@ int usermodehelper_disable(void)
  */
 void usermodehelper_enable(void)
 {
+	down_write(&umhelper_sem);
 	usermodehelper_disabled = 0;
+	up_write(&umhelper_sem);
 }
 
 /**