[RFC][PATCH 17/18 v2] ftrace/cpuidle/x86: Mark functions that are RCU unsafe

[Steven Rostedt <rostedt@goodmis.org>]

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From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>

Some callbacks of the function tracer use rcu_read_lock(). This means that
there's places that can not be traced because RCU is not tracking the CPU
for various reasons (like NO_HZ_FULL and coming back from userspace).

Thes functions need to be marked so that callbacks that use RCU do not
trace them.

Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 arch/x86/kernel/process.c |    2 ++
 drivers/cpuidle/cpuidle.c |    2 ++
 kernel/cpu/idle.c         |    2 ++
 3 files changed, 6 insertions(+)

diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 83369e5..18739cd 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -17,6 +17,7 @@
 #include <linux/stackprotector.h>
 #include <linux/tick.h>
 #include <linux/cpuidle.h>
+#include <linux/ftrace.h>
 #include <trace/events/power.h>
 #include <linux/hw_breakpoint.h>
 #include <asm/cpu.h>
@@ -316,6 +317,7 @@ void default_idle(void)
 #ifdef CONFIG_APM_MODULE
 EXPORT_SYMBOL(default_idle);
 #endif
+FTRACE_UNSAFE_RCU(default_idle);
 
 #ifdef CONFIG_XEN
 bool xen_set_default_idle(void)
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index fdc432f..9515457 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -19,6 +19,7 @@
 #include <linux/ktime.h>
 #include <linux/hrtimer.h>
 #include <linux/module.h>
+#include <linux/ftrace.h>
 #include <trace/events/power.h>
 
 #include "cpuidle.h"
@@ -168,6 +169,7 @@ int cpuidle_idle_call(void)
 
 	return 0;
 }
+FTRACE_UNSAFE_RCU(cpuidle_idle_call);
 
 /**
  * cpuidle_install_idle_handler - installs the cpuidle idle loop handler
diff --git a/kernel/cpu/idle.c b/kernel/cpu/idle.c
index e695c0a..d9d290f 100644
--- a/kernel/cpu/idle.c
+++ b/kernel/cpu/idle.c
@@ -5,6 +5,7 @@
 #include <linux/cpu.h>
 #include <linux/tick.h>
 #include <linux/mm.h>
+#include <linux/ftrace.h>
 #include <linux/stackprotector.h>
 
 #include <asm/tlb.h>
@@ -61,6 +62,7 @@ void __weak arch_cpu_idle(void)
 	cpu_idle_force_poll = 1;
 	local_irq_enable();
 }
+FTRACE_UNSAFE_RCU(arch_cpu_idle);
 
 /*
  * Generic idle loop implementation
-- 
1.7.10.4