[PATCH v8 2/3] freezer: refactor pm_freezing into a function.

[Ricardo Ribalda]

Add a way to let the drivers know if the processes are frozen.

This is needed by drivers that are waiting for processes to end on their
shutdown path.

Convert pm_freezing into a function and export it, so it can be used by
drivers that are either built-in or modules.

Cc: stable at vger.kernel.org
Fixes: 83bfc7e793b5 ("ASoC: SOF: core: unregister clients and machine drivers in .shutdown")
Signed-off-by: Ricardo Ribalda <ribalda at chromium.org>

sdad
---
 include/linux/freezer.h |  3 ++-
 kernel/freezer.c        |  3 +--
 kernel/power/process.c  | 24 ++++++++++++++++++++----
 3 files changed, 23 insertions(+), 7 deletions(-)

diff --git a/include/linux/freezer.h b/include/linux/freezer.h
index b303472255be..3413c869d68b 100644
--- a/include/linux/freezer.h
+++ b/include/linux/freezer.h
@@ -13,7 +13,7 @@
 #ifdef CONFIG_FREEZER
 DECLARE_STATIC_KEY_FALSE(freezer_active);
 
-extern bool pm_freezing;		/* PM freezing in effect */
+bool pm_freezing(void);
 extern bool pm_nosig_freezing;		/* PM nosig freezing in effect */
 
 /*
@@ -80,6 +80,7 @@ static inline int freeze_processes(void) { return -ENOSYS; }
 static inline int freeze_kernel_threads(void) { return -ENOSYS; }
 static inline void thaw_processes(void) {}
 static inline void thaw_kernel_threads(void) {}
+static inline bool pm_freezing(void) { return false; }
 
 static inline bool try_to_freeze(void) { return false; }
 
diff --git a/kernel/freezer.c b/kernel/freezer.c
index 4fad0e6fca64..2d3530ebdb7e 100644
--- a/kernel/freezer.c
+++ b/kernel/freezer.c
@@ -20,7 +20,6 @@ EXPORT_SYMBOL(freezer_active);
  * indicate whether PM freezing is in effect, protected by
  * system_transition_mutex
  */
-bool pm_freezing;
 bool pm_nosig_freezing;
 
 /* protects freezing and frozen transitions */
@@ -46,7 +45,7 @@ bool freezing_slow_path(struct task_struct *p)
 	if (pm_nosig_freezing || cgroup_freezing(p))
 		return true;
 
-	if (pm_freezing && !(p->flags & PF_KTHREAD))
+	if (pm_freezing() && !(p->flags & PF_KTHREAD))
 		return true;
 
 	return false;
diff --git a/kernel/power/process.c b/kernel/power/process.c
index ddd9988327fe..8a4d0e2c8c20 100644
--- a/kernel/power/process.c
+++ b/kernel/power/process.c
@@ -108,6 +108,22 @@ static int try_to_freeze_tasks(bool user_only)
 	return todo ? -EBUSY : 0;
 }
 
+/*
+ * Indicate whether PM freezing is in effect, protected by
+ * system_transition_mutex.
+ */
+static bool pm_freezing_internal;
+
+/**
+ * pm_freezing - indicate whether PM freezing is in effect.
+ *
+ */
+bool pm_freezing(void)
+{
+	return pm_freezing_internal;
+}
+EXPORT_SYMBOL(pm_freezing);
+
 /**
  * freeze_processes - Signal user space processes to enter the refrigerator.
  * The current thread will not be frozen.  The same process that calls
@@ -126,12 +142,12 @@ int freeze_processes(void)
 	/* Make sure this task doesn't get frozen */
 	current->flags |= PF_SUSPEND_TASK;
 
-	if (!pm_freezing)
+	if (!pm_freezing())
 		static_branch_inc(&freezer_active);
 
 	pm_wakeup_clear(0);
 	pr_info("Freezing user space processes ... ");
-	pm_freezing = true;
+	pm_freezing_internal = true;
 	error = try_to_freeze_tasks(true);
 	if (!error) {
 		__usermodehelper_set_disable_depth(UMH_DISABLED);
@@ -187,9 +203,9 @@ void thaw_processes(void)
 	struct task_struct *curr = current;
 
 	trace_suspend_resume(TPS("thaw_processes"), 0, true);
-	if (pm_freezing)
+	if (pm_freezing())
 		static_branch_dec(&freezer_active);
-	pm_freezing = false;
+	pm_freezing_internal = false;
 	pm_nosig_freezing = false;
 
 	oom_killer_enable();

-- 
2.39.0.rc0.267.gcb52ba06e7-goog-b4-0.11.0-dev-696ae