sched/clock: Move sched clock initialization and merge with generic clock

sched_clock_postinit() initializes a generic clock on systems where no
other clock is provided. This function may be called only after
timekeeping_init().

Rename sched_clock_postinit to generic_clock_inti() and call it from
sched_clock_init(). Move the call for sched_clock_init() until after
time_init().

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: steven.sistare@oracle.com
Cc: daniel.m.jordan@oracle.com
Cc: linux@armlinux.org.uk
Cc: schwidefsky@de.ibm.com
Cc: heiko.carstens@de.ibm.com
Cc: john.stultz@linaro.org
Cc: sboyd@codeaurora.org
Cc: hpa@zytor.com
Cc: douly.fnst@cn.fujitsu.com
Cc: prarit@redhat.com
Cc: feng.tang@intel.com
Cc: pmladek@suse.com
Cc: gnomes@lxorguk.ukuu.org.uk
Cc: linux-s390@vger.kernel.org
Cc: boris.ostrovsky@oracle.com
Cc: jgross@suse.com
Cc: pbonzini@redhat.com
Link: https://lkml.kernel.org/r/20180719205545.16512-23-pasha.tatashin@oracle.com

diff --git a/include/linux/sched_clock.h b/include/linux/sched_clock.h
index 411b52e..abe28d5 100644 (file)
--- a/include/linux/sched_clock.h
+++ b/include/linux/sched_clock.h
@@ -9,17 +9,16 @@
 #define LINUX_SCHED_CLOCK
 
 #ifdef CONFIG_GENERIC_SCHED_CLOCK
-extern void sched_clock_postinit(void);
+extern void generic_sched_clock_init(void);
 
 extern void sched_clock_register(u64 (*read)(void), int bits,
                                 unsigned long rate);
 #else
-static inline void sched_clock_postinit(void) { }
+static inline void generic_sched_clock_init(void) { }
 
 static inline void sched_clock_register(u64 (*read)(void), int bits,
                                        unsigned long rate)
 {
-       ;
 }
 #endif
 

diff --git a/init/main.c b/init/main.c
index 3b4ada1..162d931 100644 (file)
--- a/init/main.c
+++ b/init/main.c
@@ -79,7 +79,7 @@
 #include <linux/pti.h>
 #include <linux/blkdev.h>
 #include <linux/elevator.h>
-#include <linux/sched_clock.h>
+#include <linux/sched/clock.h>
 #include <linux/sched/task.h>
 #include <linux/sched/task_stack.h>
 #include <linux/context_tracking.h>
@@ -642,7 +642,7 @@ asmlinkage __visible void __init start_kernel(void)
        softirq_init();
        timekeeping_init();
        time_init();
-       sched_clock_postinit();
+       sched_clock_init();
        printk_safe_init();
        perf_event_init();
        profile_init();

diff --git a/kernel/sched/clock.c b/kernel/sched/clock.c
index 10c83e7..0e9dbb2 100644 (file)
--- a/kernel/sched/clock.c
+++ b/kernel/sched/clock.c
@@ -53,6 +53,7 @@
  *
  */
 #include "sched.h"
+#include <linux/sched_clock.h>
 
 /*
  * Scheduler clock - returns current time in nanosec units.
@@ -68,11 +69,6 @@ EXPORT_SYMBOL_GPL(sched_clock);
 
 __read_mostly int sched_clock_running;
 
-void sched_clock_init(void)
-{
-       sched_clock_running = 1;
-}
-
 #ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK
 /*
  * We must start with !__sched_clock_stable because the unstable -> stable
@@ -199,6 +195,15 @@ void clear_sched_clock_stable(void)
                __clear_sched_clock_stable();
 }
 
+static void __sched_clock_gtod_offset(void)
+{
+       __gtod_offset = (sched_clock() + __sched_clock_offset) - ktime_get_ns();
+}
+
+void __init sched_clock_init(void)
+{
+       sched_clock_running = 1;
+}
 /*
  * We run this as late_initcall() such that it runs after all built-in drivers,
  * notably: acpi_processor and intel_idle, which can mark the TSC as unstable.
@@ -385,8 +390,6 @@ void sched_clock_tick(void)
 
 void sched_clock_tick_stable(void)
 {
-       u64 gtod, clock;
-
        if (!sched_clock_stable())
                return;
 
@@ -398,9 +401,7 @@ void sched_clock_tick_stable(void)
         * TSC to be unstable, any computation will be computing crap.
         */
        local_irq_disable();
-       gtod = ktime_get_ns();
-       clock = sched_clock();
-       __gtod_offset = (clock + __sched_clock_offset) - gtod;
+       __sched_clock_gtod_offset();
        local_irq_enable();
 }
 
@@ -434,6 +435,12 @@ EXPORT_SYMBOL_GPL(sched_clock_idle_wakeup_event);
 
 #else /* CONFIG_HAVE_UNSTABLE_SCHED_CLOCK */
 
+void __init sched_clock_init(void)
+{
+       sched_clock_running = 1;
+       generic_sched_clock_init();
+}
+
 u64 sched_clock_cpu(int cpu)
 {
        if (unlikely(!sched_clock_running))

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index fe365c9..552406e 100644 (file)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5954,7 +5954,6 @@ void __init sched_init(void)
        int i, j;
        unsigned long alloc_size = 0, ptr;
 
-       sched_clock_init();
        wait_bit_init();
 
 #ifdef CONFIG_FAIR_GROUP_SCHED

diff --git a/kernel/time/sched_clock.c b/kernel/time/sched_clock.c
index 2d8f05a..cbc72c2 100644 (file)
--- a/kernel/time/sched_clock.c
+++ b/kernel/time/sched_clock.c
@@ -237,7 +237,7 @@ sched_clock_register(u64 (*read)(void), int bits, unsigned long rate)
        pr_debug("Registered %pF as sched_clock source\n", read);
 }
 
-void __init sched_clock_postinit(void)
+void __init generic_sched_clock_init(void)
 {
        /*
         * If no sched_clock() function has been provided at that point,