[PATCH 1/8] clocksource/drivers/arm_global_timer: Prevent ftrace recursion
From: Daniel Lezcano <hidden>
Date: 2015-10-28 13:11:52
Also in:
lkml
Subsystem:
arm/sti architecture, clocksource, clockevent drivers, the rest · Maintainers:
Patrice Chotard, Daniel Lezcano, Thomas Gleixner, Linus Torvalds
From: Jisheng Zhang <redacted> Currently arm_global_timer can be used as a scheduler clock. We properly marked gt_sched_clock_read() as notrace but we then call another function gt_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 gt_counter_read() traceable. Signed-off-by: Jisheng Zhang <redacted> Signed-off-by: Daniel Lezcano <redacted> --- drivers/clocksource/arm_global_timer.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/drivers/clocksource/arm_global_timer.c b/drivers/clocksource/arm_global_timer.c
index 29ea50a..a2cb6fa 100644
--- a/drivers/clocksource/arm_global_timer.c
+++ b/drivers/clocksource/arm_global_timer.c@@ -60,7 +60,7 @@ static struct clock_event_device __percpu *gt_evt; * different to the 32-bit upper value read previously, go back to step 2. * Otherwise the 64-bit timer counter value is correct. */ -static u64 gt_counter_read(void) +static u64 notrace _gt_counter_read(void) { u64 counter; u32 lower;
@@ -79,6 +79,11 @@ static u64 gt_counter_read(void) return counter; } +static u64 gt_counter_read(void) +{ + return _gt_counter_read(); +} + /** * To ensure that updates to comparator value register do not set the * Interrupt Status Register proceed as follows:
@@ -201,7 +206,7 @@ static struct clocksource gt_clocksource = { #ifdef CONFIG_CLKSRC_ARM_GLOBAL_TIMER_SCHED_CLOCK static u64 notrace gt_sched_clock_read(void) { - return gt_counter_read(); + return _gt_counter_read(); } #endif
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1.9.1