From: Marcelo Tosatti <mtosatti@redhat.com>
Date: Wed, 28 Nov 2012 01:28:54 +0000 (-0200)
Subject: sched: add notifier for cross-cpu migrations
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=582b336ec2c0f0076f5650a029fcc9abd4a906f7;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git

sched: add notifier for cross-cpu migrations

Originally from Jeremy Fitzhardinge.

Acked-by: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
---

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 0dd42a02df2e..6eb2ed819e36 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -107,6 +107,14 @@ extern unsigned long this_cpu_load(void);
 extern void calc_global_load(unsigned long ticks);
 extern void update_cpu_load_nohz(void);
 
+/* Notifier for when a task gets migrated to a new CPU */
+struct task_migration_notifier {
+	struct task_struct *task;
+	int from_cpu;
+	int to_cpu;
+};
+extern void register_task_migration_notifier(struct notifier_block *n);
+
 extern unsigned long get_parent_ip(unsigned long addr);
 
 struct seq_file;
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 2d8927fda712..c86b8b6e70f4 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -922,6 +922,13 @@ void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags)
 		rq->skip_clock_update = 1;
 }
 
+static ATOMIC_NOTIFIER_HEAD(task_migration_notifier);
+
+void register_task_migration_notifier(struct notifier_block *n)
+{
+	atomic_notifier_chain_register(&task_migration_notifier, n);
+}
+
 #ifdef CONFIG_SMP
 void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
 {
@@ -952,8 +959,16 @@ void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
 	trace_sched_migrate_task(p, new_cpu);
 
 	if (task_cpu(p) != new_cpu) {
+		struct task_migration_notifier tmn;
+
 		p->se.nr_migrations++;
 		perf_sw_event(PERF_COUNT_SW_CPU_MIGRATIONS, 1, NULL, 0);
+
+		tmn.task = p;
+		tmn.from_cpu = task_cpu(p);
+		tmn.to_cpu = new_cpu;
+
+		atomic_notifier_call_chain(&task_migration_notifier, 0, &tmn);
 	}
 
 	__set_task_cpu(p, new_cpu);