ARM: sched_clock: allow init_sched_clock() to be called early

sched_clock is supposed to be initialized early - in the recently added
init_early platform hook.  However, in doing so we end up calling
mod_timer() before the timer lists are initialized, resulting in an
oops.

Split the initialization in two - the part which the platform calls
early which starts things off.  The addition of the timer can be
delayed until after we have more of the kernel initialized - when the
normal time sources are initialized.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

3 files changed, 12 insertions, 1 deletions

diff --git a/arch/arm/include/asm/sched_clock.h b/arch/arm/include/asm/sched_clock.h
index a84628be1a7b..c8e6ddf3e860 100644
--- a/arch/arm/include/asm/sched_clock.h
+++ b/arch/arm/include/asm/sched_clock.h
@@ -115,4 +115,6 @@ static inline void init_fixed_sched_clock(struct clock_data *cd,
         }
 }
 
+extern void sched_clock_postinit(void);
+
 #endif
diff --git a/arch/arm/kernel/sched_clock.c b/arch/arm/kernel/sched_clock.c
index 2cdcc9287c74..784464a21c1c 100644
--- a/arch/arm/kernel/sched_clock.c
+++ b/arch/arm/kernel/sched_clock.c
@@ -60,10 +60,15 @@ void __init init_sched_clock(struct clock_data *cd, void (*update)(void),
          * sets the initial epoch.
          */
         sched_clock_timer.data = msecs_to_jiffies(w - (w / 10));
-        sched_clock_poll(sched_clock_timer.data);
+        update();
 
         /*
          * Ensure that sched_clock() starts off at 0ns
          */
         cd->epoch_ns = 0;
 }
+
+void __init sched_clock_postinit(void)
+{
+        sched_clock_poll(sched_clock_timer.data);
+}
diff --git a/arch/arm/kernel/time.c b/arch/arm/kernel/time.c
index f1e2eb19a67d..3d76bf233734 100644
--- a/arch/arm/kernel/time.c
+++ b/arch/arm/kernel/time.c
@@ -29,6 +29,7 @@
 
 #include <asm/leds.h>
 #include <asm/thread_info.h>
+#include <asm/sched_clock.h>
 #include <asm/stacktrace.h>
 #include <asm/mach/arch.h>
 #include <asm/mach/time.h>
@@ -163,5 +164,8 @@ void __init time_init(void)
 {
         system_timer = machine_desc->timer;
         system_timer->init();
+#ifdef CONFIG_HAVE_SCHED_CLOCK
+        sched_clock_postinit();
+#endif
 }