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clocksource/drivers/arm_global_timer: Prevent ftrace recursion 

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 <jszhang@marvell.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
This commit is contained in:
Jisheng Zhang 2015-10-20 16:02:34 +08:00 committed by Daniel Lezcano
parent 56fd16caba
commit d6df3576e6
1 changed files with 7 additions and 2 deletions
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9
drivers/clocksource/arm_global_timer.c
View File

@ -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. * different to the 32-bit upper value read previously, go back to step 2.
* Otherwise the 64-bit timer counter value is correct. * Otherwise the 64-bit timer counter value is correct.
*/ */
static u64 gt_counter_read(void) static u64 notrace _gt_counter_read(void)
{ {
u64 counter; u64 counter;
u32 lower; u32 lower;
@ -79,6 +79,11 @@ static u64 gt_counter_read(void)
return counter; return counter;
} }
static u64 gt_counter_read(void)
{
return _gt_counter_read();
}
/** /**
* To ensure that updates to comparator value register do not set the * To ensure that updates to comparator value register do not set the
* Interrupt Status Register proceed as follows: * Interrupt Status Register proceed as follows:
@ -201,7 +206,7 @@ static struct clocksource gt_clocksource = {
#ifdef CONFIG_CLKSRC_ARM_GLOBAL_TIMER_SCHED_CLOCK #ifdef CONFIG_CLKSRC_ARM_GLOBAL_TIMER_SCHED_CLOCK
static u64 notrace gt_sched_clock_read(void) static u64 notrace gt_sched_clock_read(void)
{ {
return gt_counter_read(); return _gt_counter_read();
} }
#endif #endif