1 files changed, 27 insertions, 0 deletions

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 8c1c9c0f4775..7e9a20b69939 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -17,6 +17,7 @@
 #include <linux/clocksource.h>
 #include <linux/kallsyms.h>
 #include <linux/seq_file.h>
+#include <linux/suspend.h>
 #include <linux/debugfs.h>
 #include <linux/hardirq.h>
 #include <linux/kthread.h>
@@ -1957,6 +1958,7 @@ ftrace_enable_sysctl(struct ctl_table *table, int write,
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 
 static atomic_t ftrace_graph_active;
+static struct notifier_block ftrace_suspend_notifier;
 
 int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace)
 {
@@ -2035,6 +2037,27 @@ static int start_graph_tracing(void)
         return ret;
 }
 
+/*
+ * Hibernation protection.
+ * The state of the current task is too much unstable during
+ * suspend/restore to disk. We want to protect against that.
+ */
+static int
+ftrace_suspend_notifier_call(struct notifier_block *bl, unsigned long state,
+                                                        void *unused)
+{
+        switch (state) {
+        case PM_HIBERNATION_PREPARE:
+                pause_graph_tracing();
+                break;
+
+        case PM_POST_HIBERNATION:
+                unpause_graph_tracing();
+                break;
+        }
+        return NOTIFY_DONE;
+}
+
 int register_ftrace_graph(trace_func_graph_ret_t retfunc,
                         trace_func_graph_ent_t entryfunc)
 {
@@ -2042,6 +2065,9 @@ int register_ftrace_graph(trace_func_graph_ret_t retfunc,
 
         mutex_lock(&ftrace_sysctl_lock);
 
+        ftrace_suspend_notifier.notifier_call = ftrace_suspend_notifier_call;
+        register_pm_notifier(&ftrace_suspend_notifier);
+
         atomic_inc(&ftrace_graph_active);
         ret = start_graph_tracing();
         if (ret) {
@@ -2067,6 +2093,7 @@ void unregister_ftrace_graph(void)
         ftrace_graph_return = (trace_func_graph_ret_t)ftrace_stub;
         ftrace_graph_entry = ftrace_graph_entry_stub;
         ftrace_shutdown(FTRACE_STOP_FUNC_RET);
+        unregister_pm_notifier(&ftrace_suspend_notifier);
 
         mutex_unlock(&ftrace_sysctl_lock);
 }