[PATCH 3/8] clocksource/drivers/samsung_pwm_timer: Prevent ftrace recursion

From: Daniel Lezcano
Date: Wed Oct 28 2015 - 09:12:09 EST

From: Jisheng Zhang <jszhang@xxxxxxxxxxx>

Currently samsung_pwm_timer can be used as a scheduler clock. We properly
marked samsung_read_sched_clock() as notrace but we then call another
function samsung_clocksource_read() that _wasn't_ notrace.

Having a traceable function in the sched_clock() path leads to a recursion
within ftrace and a kernel crash.

Fix this by adding notrace attribute to the samsung_clocksource_read()

Signed-off-by: Jisheng Zhang <jszhang@xxxxxxxxxxx>
Signed-off-by: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
drivers/clocksource/samsung_pwm_timer.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/clocksource/samsung_pwm_timer.c b/drivers/clocksource/samsung_pwm_timer.c
index bc90e13..9502bc4 100644
--- a/drivers/clocksource/samsung_pwm_timer.c
+++ b/drivers/clocksource/samsung_pwm_timer.c
@@ -307,7 +307,7 @@ static void samsung_clocksource_resume(struct clocksource *cs)
samsung_time_start(pwm.source_id, true);

-static cycle_t samsung_clocksource_read(struct clocksource *c)
+static cycle_t notrace samsung_clocksource_read(struct clocksource *c)
return ~readl_relaxed(pwm.source_reg);

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