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

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: Ben Hutchings <ben@decadent.org.uk>

diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index 7c0d578..013bd2e 100644 (file)
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -367,6 +367,7 @@ int hibernation_snapshot(int platform_mode)
        }
 
        suspend_console();
+       ftrace_stop();
        pm_restrict_gfp_mask();
        error = dpm_suspend(PMSG_FREEZE);
        if (error)
@@ -392,6 +393,7 @@ int hibernation_snapshot(int platform_mode)
        if (error || !in_suspend)
                pm_restore_gfp_mask();
 
+       ftrace_start();
        resume_console();
        dpm_complete(msg);
 
@@ -496,6 +498,7 @@ 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) {
@@ -503,6 +506,7 @@ int hibernation_restore(int platform_mode)
                dpm_resume_end(PMSG_RECOVER);
        }
        pm_restore_gfp_mask();
+       ftrace_start();
        resume_console();
        pm_restore_console();
        return error;
@@ -529,6 +533,7 @@ 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)
@@ -572,6 +577,7 @@ 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 4953dc0..af48faa 100644 (file)
--- a/kernel/power/suspend.c
+++ b/kernel/power/suspend.c
@@ -25,6 +25,7 @@
 #include <linux/export.h>
 #include <linux/suspend.h>
 #include <linux/syscore_ops.h>
+#include <linux/ftrace.h>
 #include <trace/events/power.h>
 
 #include "power.h"
@@ -220,6 +221,7 @@ 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) {
@@ -239,6 +241,7 @@ 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)