[PATCH v3 13/13] clocksource/drivers/rockchip_timer: Prevent ftrace recursion
From: Alexander Kochetkov <hidden>
Date: 2016-11-29 13:46:51
Also in:
linux-devicetree, linux-rockchip, lkml
Subsystem:
arm/rockchip soc support, clocksource, clockevent drivers, the rest · Maintainers:
Heiko Stuebner, Daniel Lezcano, Thomas Gleixner, Linus Torvalds
Currently rockchip_timer can be used as a scheduler clock. We properly marked rk_timer_sched_clock_read() as notrace but we then call another function rk_timer_counter_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 an extra notrace function to keep other users of rk_timer_counter_read() traceable. Signed-off-by: Alexander Kochetkov <redacted> --- drivers/clocksource/rockchip_timer.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/drivers/clocksource/rockchip_timer.c b/drivers/clocksource/rockchip_timer.c
index 1af80a0..a127822 100644
--- a/drivers/clocksource/rockchip_timer.c
+++ b/drivers/clocksource/rockchip_timer.c@@ -87,7 +87,7 @@ static void rk_timer_update_counter(u64 cycles, struct rk_timer *timer) writel_relaxed(upper, timer->base + TIMER_LOAD_COUNT1); } -static u64 rk_timer_counter_read(struct rk_timer *timer) +static u64 notrace _rk_timer_counter_read(struct rk_timer *timer) { u64 counter; u32 lower;
@@ -106,6 +106,11 @@ static u64 rk_timer_counter_read(struct rk_timer *timer) return counter; } +static u64 rk_timer_counter_read(struct rk_timer *timer) +{ + return _rk_timer_counter_read(timer); +} + static void rk_timer_interrupt_clear(struct rk_timer *timer) { writel_relaxed(1, timer->base + TIMER_INT_STATUS);
@@ -168,7 +173,7 @@ static u64 notrace rk_timer_sched_clock_read(void) { struct rk_clocksource *_cs = &cs_timer; - return ~rk_timer_counter_read(&_cs->timer); + return ~_rk_timer_counter_read(&_cs->timer); } static int __init rk_timer_init(struct device_node *np, u32 ctrl_reg)
--
1.7.9.5