[PATCH 04/14] sched: update sched_notifier and add wakeup/sleep notifications

Tejun Heo
2009-11-23T16:30:03Z

Update sched_notifier such that

* in and out ops are symmetric in the parameter they take.

* Use single fire_sched_notifier() macro instead of separate function
for each op.

* Allow NULL ops.

* Add wakeup and sleep notifications.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Avi Kivity <avi@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
---
include/linux/sched.h | 20 +++++++++++++-------
kernel/sched.c | 41 ++++++++++++++++++-----------------------
virt/kvm/kvm_main.c | 4 ++--
3 files changed, 33 insertions(+), 32 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 37c97a1..657372f 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1214,15 +1214,21 @@ struct sched_notifier;

/**
* sched_notifier_ops - notifiers called for scheduling events
- * @in: we're about to be rescheduled:
- * notifier: struct sched_notifier for the task being scheduled
- * cpu: cpu we're scheduled on
- * @out: we've just been preempted
- * notifier: struct sched_notifier for the task being preempted
- * next: the task that's kicking us out
+ * @wakeup: we're waking up
+ * notifier: struct sched_notifier for the task being woken up
+ * @sleep: we're going to bed
+ * notifier: struct sched_notifier for the task sleeping
+ * @in: we're now running on the cpu
+ * notifier: struct sched_notifier for the task being scheduled in
+ * prev: the task which ran before us
+ * @out: we're leaving the cpu
+ * notifier: struct sched_notifier for the task being scheduled out
+ * next: the task which will run after us
*/
struct sched_notifier_ops {
- void (*in)(struct sched_notifier *notifier, int cpu);
+ void (*wakeup)(struct sched_notifier *notifier);
+ void (*sleep)(struct sched_notifier *notifier);
+ void (*in)(struct sched_notifier *notifier, struct task_struct *prev);
void (*out)(struct sched_notifier *notifier, struct task_struct *next);
};

diff --git a/kernel/sched.c b/kernel/sched.c
index 7ef5757..da0513e 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1389,6 +1389,16 @@ static const u32 prio_to_wmult[40] = {
/* 15 */ 119304647, 148102320, 186737708, 238609294, 286331153,
};

+#define fire_sched_notifier(p, callback, args...) do { \
+ struct task_struct *__p = (p); \
+ struct sched_notifier *__sn; \
+ struct hlist_node *__pos; \
+ \
+ hlist_for_each_entry(__sn, __pos, &__p->sched_notifiers, link) \
+ if (__sn->ops->callback) \
+ __sn->ops->callback(__sn , ##args); \
+} while (0)
+
static void activate_task(struct rq *rq, struct task_struct *p, int wakeup);

/*
@@ -2441,6 +2451,8 @@ out_running:
if (p->sched_class->task_wake_up)
p->sched_class->task_wake_up(rq, p);
#endif
+ if (success)
+ fire_sched_notifier(p, wakeup);
out:
task_rq_unlock(rq, &flags);
put_cpu();
@@ -2653,25 +2665,6 @@ void sched_notifier_unregister(struct sched_notifier *notifier)
}
EXPORT_SYMBOL_GPL(sched_notifier_unregister);

-static void fire_sched_in_notifiers(struct task_struct *curr)
-{
- struct sched_notifier *notifier;
- struct hlist_node *node;
-
- hlist_for_each_entry(notifier, node, &curr->sched_notifiers, link)
- notifier->ops->in(notifier, raw_smp_processor_id());
-}
-
-static void fire_sched_out_notifiers(struct task_struct *curr,
- struct task_struct *next)
-{
- struct sched_notifier *notifier;
- struct hlist_node *node;
-
- hlist_for_each_entry(notifier, node, &curr->sched_notifiers, link)
- notifier->ops->out(notifier, next);
-}
-
/**
* prepare_task_switch - prepare to switch tasks
* @rq: the runqueue preparing to switch
@@ -2689,7 +2682,7 @@ static inline void
prepare_task_switch(struct rq *rq, struct task_struct *prev,
struct task_struct *next)
{
- fire_sched_out_notifiers(prev, next);
+ fire_sched_notifier(current, out, next);
prepare_lock_switch(rq, next);
prepare_arch_switch(next);
}
@@ -2731,7 +2724,7 @@ static void finish_task_switch(struct rq *rq, struct task_struct *prev)
prev_state = prev->state;
finish_arch_switch(prev);
perf_event_task_sched_in(current, cpu_of(rq));
- fire_sched_in_notifiers(current);
+ fire_sched_notifier(current, in, prev);
finish_lock_switch(rq, prev);

if (mm)
@@ -5417,10 +5410,12 @@ need_resched_nonpreemptible:
clear_tsk_need_resched(prev);

if (prev->state && !(preempt_count() & PREEMPT_ACTIVE)) {
- if (unlikely(signal_pending_state(prev->state, prev)))
+ if (unlikely(signal_pending_state(prev->state, prev))) {
prev->state = TASK_RUNNING;
- else
+ } else {
+ fire_sched_notifier(prev, sleep);
deactivate_task(rq, prev, 1);
+ }
switch_count = &prev->nvcsw;
}

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 4e8e33f..006358d 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2695,11 +2695,11 @@ static inline struct kvm_vcpu *sched_notifier_to_vcpu(struct sched_notifier *sn)
return container_of(sn, struct kvm_vcpu, sched_notifier);
}

-static void kvm_sched_in(struct sched_notifier *sn, int cpu)
+static void kvm_sched_in(struct sched_notifier *sn, struct task_struct *prev)
{
struct kvm_vcpu *vcpu = sched_notifier_to_vcpu(sn);

- kvm_arch_vcpu_load(vcpu, cpu);
+ kvm_arch_vcpu_load(vcpu, smp_processor_id());
}

static void kvm_sched_out(struct sched_notifier *sn, struct task_struct *next)
--
1.6.5.3