diff options
| -rw-r--r-- | include/linux/preempt.h | 44 | ||||
| -rw-r--r-- | include/linux/sched.h | 5 | ||||
| -rw-r--r-- | kernel/Kconfig.preempt | 3 | ||||
| -rw-r--r-- | kernel/sched.c | 73 |
4 files changed, 123 insertions, 2 deletions
diff --git a/include/linux/preempt.h b/include/linux/preempt.h index d0926d63406c..484988ed301e 100644 --- a/include/linux/preempt.h +++ b/include/linux/preempt.h @@ -8,6 +8,7 @@ #include <linux/thread_info.h> #include <linux/linkage.h> +#include <linux/list.h> #ifdef CONFIG_DEBUG_PREEMPT extern void fastcall add_preempt_count(int val); @@ -60,4 +61,47 @@ do { \ #endif +#ifdef CONFIG_PREEMPT_NOTIFIERS + +struct preempt_notifier; + +/** + * preempt_ops - notifiers called when a task is preempted and rescheduled + * @sched_in: we're about to be rescheduled: + * notifier: struct preempt_notifier for the task being scheduled + * cpu: cpu we're scheduled on + * @sched_out: we've just been preempted + * notifier: struct preempt_notifier for the task being preempted + * next: the task that's kicking us out + */ +struct preempt_ops { + void (*sched_in)(struct preempt_notifier *notifier, int cpu); + void (*sched_out)(struct preempt_notifier *notifier, + struct task_struct *next); +}; + +/** + * preempt_notifier - key for installing preemption notifiers + * @link: internal use + * @ops: defines the notifier functions to be called + * + * Usually used in conjunction with container_of(). + */ +struct preempt_notifier { + struct hlist_node link; + struct preempt_ops *ops; +}; + +void preempt_notifier_register(struct preempt_notifier *notifier); +void preempt_notifier_unregister(struct preempt_notifier *notifier); + +static inline void preempt_notifier_init(struct preempt_notifier *notifier, + struct preempt_ops *ops) +{ + INIT_HLIST_NODE(¬ifier->link); + notifier->ops = ops; +} + +#endif + #endif /* __LINUX_PREEMPT_H */ diff --git a/include/linux/sched.h b/include/linux/sched.h index 7c61b50823fa..7a4de8768748 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -935,6 +935,11 @@ struct task_struct { struct sched_class *sched_class; struct sched_entity se; +#ifdef CONFIG_PREEMPT_NOTIFIERS + /* list of struct preempt_notifier: */ + struct hlist_head preempt_notifiers; +#endif + unsigned short ioprio; #ifdef CONFIG_BLK_DEV_IO_TRACE unsigned int btrace_seq; diff --git a/kernel/Kconfig.preempt b/kernel/Kconfig.preempt index c64ce9c14207..6b066632e40c 100644 --- a/kernel/Kconfig.preempt +++ b/kernel/Kconfig.preempt @@ -63,3 +63,6 @@ config PREEMPT_BKL Say Y here if you are building a kernel for a desktop system. Say N if you are unsure. +config PREEMPT_NOTIFIERS + bool + diff --git a/kernel/sched.c b/kernel/sched.c index 93cf241cfbe9..e901aa59f206 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -1592,6 +1592,10 @@ static void __sched_fork(struct task_struct *p) INIT_LIST_HEAD(&p->run_list); p->se.on_rq = 0; +#ifdef CONFIG_PREEMPT_NOTIFIERS + INIT_HLIST_HEAD(&p->preempt_notifiers); +#endif + /* * We mark the process as running here, but have not actually * inserted it onto the runqueue yet. This guarantees that @@ -1673,6 +1677,63 @@ void fastcall wake_up_new_task(struct task_struct *p, unsigned long clone_flags) task_rq_unlock(rq, &flags); } +#ifdef CONFIG_PREEMPT_NOTIFIERS + +/** + * preempt_notifier_register - tell me when current is being being preempted + * and rescheduled + */ +void preempt_notifier_register(struct preempt_notifier *notifier) +{ + hlist_add_head(¬ifier->link, ¤t->preempt_notifiers); +} +EXPORT_SYMBOL_GPL(preempt_notifier_register); + +/** + * preempt_notifier_unregister - no longer interested in preemption notifications + * + * This is safe to call from within a preemption notifier. + */ +void preempt_notifier_unregister(struct preempt_notifier *notifier) +{ + hlist_del(¬ifier->link); +} +EXPORT_SYMBOL_GPL(preempt_notifier_unregister); + +static void fire_sched_in_preempt_notifiers(struct task_struct *curr) +{ + struct preempt_notifier *notifier; + struct hlist_node *node; + + hlist_for_each_entry(notifier, node, &curr->preempt_notifiers, link) + notifier->ops->sched_in(notifier, raw_smp_processor_id()); +} + +static void +fire_sched_out_preempt_notifiers(struct task_struct *curr, + struct task_struct *next) +{ + struct preempt_notifier *notifier; + struct hlist_node *node; + + hlist_for_each_entry(notifier, node, &curr->preempt_notifiers, link) + notifier->ops->sched_out(notifier, next); +} + +#else + +static void fire_sched_in_preempt_notifiers(struct task_struct *curr) +{ +} + +static void +fire_sched_out_preempt_notifiers(struct task_struct *curr, + struct task_struct *next) +{ +} + +#endif + /** * prepare_task_switch - prepare to switch tasks * @rq: the runqueue preparing to switch @@ -1685,8 +1746,11 @@ void fastcall wake_up_new_task(struct task_struct *p, unsigned long clone_flags) * prepare_task_switch sets up locking and calls architecture specific * hooks. */ -static inline void prepare_task_switch(struct rq *rq, struct task_struct *next) +static inline void +prepare_task_switch(struct rq *rq, struct task_struct *prev, + struct task_struct *next) { + fire_sched_out_preempt_notifiers(prev, next); prepare_lock_switch(rq, next); prepare_arch_switch(next); } @@ -1728,6 +1792,7 @@ static inline void finish_task_switch(struct rq *rq, struct task_struct *prev) prev_state = prev->state; finish_arch_switch(prev); finish_lock_switch(rq, prev); + fire_sched_in_preempt_notifiers(current); if (mm) mmdrop(mm); if (unlikely(prev_state == TASK_DEAD)) { @@ -1768,7 +1833,7 @@ context_switch(struct rq *rq, struct task_struct *prev, { struct mm_struct *mm, *oldmm; - prepare_task_switch(rq, next); + prepare_task_switch(rq, prev, next); mm = next->mm; oldmm = prev->active_mm; /* @@ -6335,6 +6400,10 @@ void __init sched_init(void) set_load_weight(&init_task); +#ifdef CONFIG_PREEMPT_NOTIFIERS + INIT_HLIST_HEAD(&init_task.preempt_notifiers); +#endif + #ifdef CONFIG_SMP nr_cpu_ids = highest_cpu + 1; open_softirq(SCHED_SOFTIRQ, run_rebalance_domains, NULL); |