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Subject[PATCH 4.14 162/165] watchdog: Mark watchdog touch functions as notrace
Date
4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Vincent Whitchurch <vincent.whitchurch@axis.com>

commit cb9d7fd51d9fbb329d182423bd7b92d0f8cb0e01 upstream.

Some architectures need to use stop_machine() to patch functions for
ftrace, and the assumption is that the stopped CPUs do not make function
calls to traceable functions when they are in the stopped state.

Commit ce4f06dcbb5d ("stop_machine: Touch_nmi_watchdog() after
MULTI_STOP_PREPARE") added calls to the watchdog touch functions from
the stopped CPUs and those functions lack notrace annotations. This
leads to crashes when enabling/disabling ftrace on ARM kernels built
with the Thumb-2 instruction set.

Fix it by adding the necessary notrace annotations.

Fixes: ce4f06dcbb5d ("stop_machine: Touch_nmi_watchdog() after MULTI_STOP_PREPARE")
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: oleg@redhat.com
Cc: tj@kernel.org
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20180821152507.18313-1-vincent.whitchurch@axis.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
kernel/watchdog.c | 4 ++--
kernel/watchdog_hld.c | 2 +-
kernel/workqueue.c | 2 +-
3 files changed, 4 insertions(+), 4 deletions(-)

--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -265,7 +265,7 @@ static void __touch_watchdog(void)
* entering idle state. This should only be used for scheduler events.
* Use touch_softlockup_watchdog() for everything else.
*/
-void touch_softlockup_watchdog_sched(void)
+notrace void touch_softlockup_watchdog_sched(void)
{
/*
* Preemption can be enabled. It doesn't matter which CPU's timestamp
@@ -274,7 +274,7 @@ void touch_softlockup_watchdog_sched(voi
raw_cpu_write(watchdog_touch_ts, 0);
}

-void touch_softlockup_watchdog(void)
+notrace void touch_softlockup_watchdog(void)
{
touch_softlockup_watchdog_sched();
wq_watchdog_touch(raw_smp_processor_id());
--- a/kernel/watchdog_hld.c
+++ b/kernel/watchdog_hld.c
@@ -29,7 +29,7 @@ static struct cpumask dead_events_mask;
static unsigned long hardlockup_allcpu_dumped;
static atomic_t watchdog_cpus = ATOMIC_INIT(0);

-void arch_touch_nmi_watchdog(void)
+notrace void arch_touch_nmi_watchdog(void)
{
/*
* Using __raw here because some code paths have
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -5484,7 +5484,7 @@ static void wq_watchdog_timer_fn(unsigne
mod_timer(&wq_watchdog_timer, jiffies + thresh);
}

-void wq_watchdog_touch(int cpu)
+notrace void wq_watchdog_touch(int cpu)
{
if (cpu >= 0)
per_cpu(wq_watchdog_touched_cpu, cpu) = jiffies;

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