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clocksource: exynos_mct: Fix ftrace 

In (93bfb76 clocksource: exynos_mct: register sched_clock callback) we
supported using the MCT as a scheduler clock.  We properly marked
exynos4_read_sched_clock() as notrace.  However, we then went and
called another function that _wasn't_ notrace.  That means if you do:

  cd /sys/kernel/debug/tracing/
  echo function_graph > current_tracer

You'll get a crash.

Fix this (but still let other readers of the MCT be trace-enabled) by
adding an extra function.  It's important to keep other users of MCT
traceable because the MCT is actually quite slow to access and we want
exynos4_frc_read() to show up in ftrace profiles if it's the
bottleneck.

Signed-off-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
This commit is contained in:
Doug Anderson 2014-07-05 06:38:55 +09:00 committed by Kukjin Kim
parent 2fd82d3301
commit 89e6a13b88
1 changed files with 7 additions and 2 deletions
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9
drivers/clocksource/exynos_mct.c
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@ -162,7 +162,7 @@ static void exynos4_mct_frc_start(void)
exynos4_mct_write(reg, EXYNOS4_MCT_G_TCON);
}
static cycle_t exynos4_frc_read(struct clocksource *cs)
static cycle_t notrace _exynos4_frc_read(void)
{
unsigned int lo, hi;
u32 hi2 = __raw_readl(reg_base + EXYNOS4_MCT_G_CNT_U);
@ -176,6 +176,11 @@ static cycle_t exynos4_frc_read(struct clocksource *cs)
return ((cycle_t)hi << 32) | lo;
}
static cycle_t exynos4_frc_read(struct clocksource *cs)
{
return _exynos4_frc_read();
}
static void exynos4_frc_resume(struct clocksource *cs)
{
exynos4_mct_frc_start();
@ -192,7 +197,7 @@ struct clocksource mct_frc = {
static u64 notrace exynos4_read_sched_clock(void)
{
return exynos4_frc_read(&mct_frc);
return _exynos4_frc_read();
}
static void __init exynos4_clocksource_init(void)