3.2-stable review patch. If anyone has any objections, please let me know.
------------------
From: "Srivatsa S. Bhat" <srivatsa.b...@linux.vnet.ibm.com>
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.b...@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <r...@sisk.pl>
Signed-off-by: Ben Hutchings <b...@decadent.org.uk>
---
kernel/power/hibernate.c | 6 ++++++
kernel/power/suspend.c | 3 +++
2 files changed, 9 insertions(+)
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -367,6 +367,7 @@ int hibernation_snapshot(int platform_mo
}
suspend_console();
+ ftrace_stop();
pm_restrict_gfp_mask();
error = dpm_suspend(PMSG_FREEZE);
if (error)
@@ -392,6 +393,7 @@ int hibernation_snapshot(int platform_mo
if (error || !in_suspend)
pm_restore_gfp_mask();
+ ftrace_start();
resume_console();
dpm_complete(msg);
@@ -496,6 +498,7 @@ int hibernation_restore(int platform_mod
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_mod
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:
--- 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_st
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_st
suspend_test_start();
dpm_resume_end(PMSG_RESUME);
suspend_test_finish("resume devices");
+ ftrace_start();
resume_console();
Close:
if (suspend_ops->end)
--
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