[PATCH 1/4] sched: define and use CPU_PRI_* enums for cpu notifier priorities

[Tejun Heo]

Instead of hardcoding priority 10 and 20 in sched and perf, collect
them into CPU_PRI_* enums.

Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 include/linux/cpu.h        |    9 +++++++++
 include/linux/perf_event.h |    2 +-
 kernel/sched.c             |    2 +-
 3 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index e287863..2d90738 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -48,6 +48,15 @@ extern ssize_t arch_cpu_release(const char *, size_t);
 #endif
 struct notifier_block;
 
+/*
+ * CPU notifier priorities.
+ */
+enum {
+	/* migration should happen before other stuff but after perf */
+	CPU_PRI_PERF		= 20,
+	CPU_PRI_MIGRATION	= 10,
+};
+
 #ifdef CONFIG_SMP
 /* Need to know about CPUs going up/down? */
 #if defined(CONFIG_HOTPLUG_CPU) || !defined(MODULE)
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index c8e3754..11a84f9 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -990,7 +990,7 @@ static inline void perf_event_disable(struct perf_event *event)		{ }
 #define perf_cpu_notifier(fn)					\
 do {								\
 	static struct notifier_block fn##_nb __cpuinitdata =	\
-		{ .notifier_call = fn, .priority = 20 };	\
+		{ .notifier_call = fn, .priority = CPU_PRI_PERF }; \
 	fn(&fn##_nb, (unsigned long)CPU_UP_PREPARE,		\
 		(void *)(unsigned long)smp_processor_id());	\
 	fn(&fn##_nb, (unsigned long)CPU_STARTING,		\
diff --git a/kernel/sched.c b/kernel/sched.c
index b531d79..7f07048 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -5837,7 +5837,7 @@ migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
  */
 static struct notifier_block __cpuinitdata migration_notifier = {
 	.notifier_call = migration_call,
-	.priority = 10
+	.priority = CPU_PRI_MIGRATION,
 };
 
 static int __init migration_init(void)
-- 
1.6.4.2

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