ftrace: Disable function tracing during suspend/resume and hibernation, again

BugLink: http://bugs.launchpad.net/bugs/1034988

commit 443772d408a25af62498793f6f805ce3c559309a upstream.

If function tracing is enabled for some of the low-level suspend/resume
functions, it leads to triple fault during resume from suspend, ultimately
ending up in a reboot instead of a resume (or a total refusal to come out
of suspended state, on some machines).

This issue was explained in more detail in commit f42ac38c59e0a03d (ftrace:
disable tracing for suspend to ram). However, the changes made by that commit
got reverted by commit cbe2f5a6e84eebb (tracing: allow tracing of
suspend/resume & hibernation code again). So, unfortunately since things are
not yet robust enough to allow tracing of low-level suspend/resume functions,
suspend/resume is still broken when ftrace is enabled.

So fix this by disabling function tracing during suspend/resume & hibernation.

Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com>

2 files changed, 9 insertions, 0 deletions

diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index 8884c27682f..32f1590644d 100644
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -344,6 +344,7 @@ int hibernation_snapshot(int platform_mode)
                 goto Complete_devices;
 
         suspend_console();
+        ftrace_stop();
         pm_restrict_gfp_mask();
         error = dpm_suspend(PMSG_FREEZE);
         if (error)
@@ -369,6 +370,7 @@ int hibernation_snapshot(int platform_mode)
         if (error || !in_suspend)
                 pm_restore_gfp_mask();
 
+        ftrace_start();
         resume_console();
 
  Complete_devices:
@@ -471,6 +473,7 @@ int hibernation_restore(int platform_mode)
 
         pm_prepare_console();
         suspend_console();
+        ftrace_stop();
         pm_restrict_gfp_mask();
         error = dpm_suspend_start(PMSG_QUIESCE);
         if (!error) {
@@ -478,6 +481,7 @@ int hibernation_restore(int platform_mode)
                 dpm_resume_end(PMSG_RECOVER);
         }
         pm_restore_gfp_mask();
+        ftrace_start();
         resume_console();
         pm_restore_console();
         return error;
@@ -504,6 +508,7 @@ int hibernation_platform_enter(void)
 
         entering_platform_hibernation = true;
         suspend_console();
+        ftrace_stop();
         error = dpm_suspend_start(PMSG_HIBERNATE);
         if (error) {
                 if (hibernation_ops->recover)
@@ -547,6 +552,7 @@ int hibernation_platform_enter(void)
  Resume_devices:
         entering_platform_hibernation = false;
         dpm_resume_end(PMSG_RESTORE);
+        ftrace_start();
         resume_console();
 
  Close:
diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c
index 449ccc9c0a4..e40d20595b1 100644
--- a/kernel/power/suspend.c
+++ b/kernel/power/suspend.c
@@ -23,6 +23,7 @@
 #include <linux/slab.h>
 #include <linux/suspend.h>
 #include <linux/syscore_ops.h>
+#include <linux/ftrace.h>
 #include <trace/events/power.h>
 
 #include "power.h"
@@ -210,6 +211,7 @@ int suspend_devices_and_enter(suspend_state_t state)
                         goto Close;
         }
         suspend_console();
+        ftrace_stop();
         suspend_test_start();
         error = dpm_suspend_start(PMSG_SUSPEND);
         if (error) {
@@ -226,6 +228,7 @@ int suspend_devices_and_enter(suspend_state_t state)
         suspend_test_start();
         dpm_resume_end(PMSG_RESUME);
         suspend_test_finish("resume devices");
+        ftrace_start();
         resume_console();
  Close:
         if (suspend_ops->end)