On 06/19/2014 07:08 PM, Doug Anderson wrote:
In (93bfb76 clocksource: exynos_mct: register sched_clock callback) we
supported using the MCT as a scheduler clock.
Hi Thomas,
is it possible you update the tip/timers/core so I can get visibility on
the above patch to apply this one ?
Thanks
-- Daniel
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@xxxxxxxxxxxx>
---
Changes in v2:
- Split out from other patches so this can go into 3.16.
- Better comment about why exynos4_frc_read() should be traceable.
- No more useless inline.
drivers/clocksource/exynos_mct.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/drivers/clocksource/exynos_mct.c b/drivers/clocksource/exynos_mct.c
index f71d55f..5ce99c0 100644
--- a/drivers/clocksource/exynos_mct.c
+++ b/drivers/clocksource/exynos_mct.c
@@ -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)
--
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