diff options
Diffstat (limited to 'kernel/include/linux/preempt.h')
| -rw-r--r-- | kernel/include/linux/preempt.h | 250 |
1 files changed, 250 insertions, 0 deletions
diff --git a/kernel/include/linux/preempt.h b/kernel/include/linux/preempt.h new file mode 100644 index 000000000..66587bf45 --- /dev/null +++ b/kernel/include/linux/preempt.h @@ -0,0 +1,250 @@ +#ifndef __LINUX_PREEMPT_H +#define __LINUX_PREEMPT_H + +/* + * include/linux/preempt.h - macros for accessing and manipulating + * preempt_count (used for kernel preemption, interrupt count, etc.) + */ + +#include <linux/linkage.h> +#include <linux/list.h> + +/* + * We use the MSB mostly because its available; see <linux/preempt_mask.h> for + * the other bits -- can't include that header due to inclusion hell. + */ +#define PREEMPT_NEED_RESCHED 0x80000000 + +#include <asm/preempt.h> + +#if defined(CONFIG_DEBUG_PREEMPT) || defined(CONFIG_PREEMPT_TRACER) +extern void preempt_count_add(int val); +extern void preempt_count_sub(int val); +#define preempt_count_dec_and_test() ({ preempt_count_sub(1); should_resched(); }) +#else +#define preempt_count_add(val) __preempt_count_add(val) +#define preempt_count_sub(val) __preempt_count_sub(val) +#define preempt_count_dec_and_test() __preempt_count_dec_and_test() +#endif + +#define __preempt_count_inc() __preempt_count_add(1) +#define __preempt_count_dec() __preempt_count_sub(1) + +#define preempt_count_inc() preempt_count_add(1) +#define preempt_count_dec() preempt_count_sub(1) + +#ifdef CONFIG_PREEMPT_LAZY +#define add_preempt_lazy_count(val) do { preempt_lazy_count() += (val); } while (0) +#define sub_preempt_lazy_count(val) do { preempt_lazy_count() -= (val); } while (0) +#define inc_preempt_lazy_count() add_preempt_lazy_count(1) +#define dec_preempt_lazy_count() sub_preempt_lazy_count(1) +#define preempt_lazy_count() (current_thread_info()->preempt_lazy_count) +#else +#define add_preempt_lazy_count(val) do { } while (0) +#define sub_preempt_lazy_count(val) do { } while (0) +#define inc_preempt_lazy_count() do { } while (0) +#define dec_preempt_lazy_count() do { } while (0) +#define preempt_lazy_count() (0) +#endif + +#ifdef CONFIG_PREEMPT_COUNT + +#define preempt_disable() \ +do { \ + preempt_count_inc(); \ + barrier(); \ +} while (0) + +#define preempt_lazy_disable() \ +do { \ + inc_preempt_lazy_count(); \ + barrier(); \ +} while (0) + +#define sched_preempt_enable_no_resched() \ +do { \ + barrier(); \ + preempt_count_dec(); \ +} while (0) + +#ifdef CONFIG_PREEMPT_RT_BASE +# define preempt_enable_no_resched() sched_preempt_enable_no_resched() +# define preempt_check_resched_rt() preempt_check_resched() +#else +# define preempt_enable_no_resched() preempt_enable() +# define preempt_check_resched_rt() barrier(); +#endif + +#ifdef CONFIG_PREEMPT +#define preempt_enable() \ +do { \ + barrier(); \ + if (unlikely(preempt_count_dec_and_test())) \ + __preempt_schedule(); \ +} while (0) + +#define preempt_check_resched() \ +do { \ + if (should_resched()) \ + __preempt_schedule(); \ +} while (0) + +#define preempt_lazy_enable() \ +do { \ + dec_preempt_lazy_count(); \ + barrier(); \ + preempt_check_resched(); \ +} while (0) + +#else +#define preempt_enable() \ +do { \ + barrier(); \ + preempt_count_dec(); \ +} while (0) +#define preempt_check_resched() do { } while (0) +#endif + +#define preempt_disable_notrace() \ +do { \ + __preempt_count_inc(); \ + barrier(); \ +} while (0) + +#define preempt_enable_no_resched_notrace() \ +do { \ + barrier(); \ + __preempt_count_dec(); \ +} while (0) + +#ifdef CONFIG_PREEMPT + +#ifndef CONFIG_CONTEXT_TRACKING +#define __preempt_schedule_context() __preempt_schedule() +#endif + +#define preempt_enable_notrace() \ +do { \ + barrier(); \ + if (unlikely(__preempt_count_dec_and_test())) \ + __preempt_schedule_context(); \ +} while (0) +#else +#define preempt_enable_notrace() \ +do { \ + barrier(); \ + __preempt_count_dec(); \ +} while (0) +#endif + +#else /* !CONFIG_PREEMPT_COUNT */ + +/* + * Even if we don't have any preemption, we need preempt disable/enable + * to be barriers, so that we don't have things like get_user/put_user + * that can cause faults and scheduling migrate into our preempt-protected + * region. + */ +#define preempt_disable() barrier() +#define sched_preempt_enable_no_resched() barrier() +#define preempt_enable_no_resched() barrier() +#define preempt_enable() barrier() +#define preempt_check_resched() do { } while (0) + +#define preempt_disable_notrace() barrier() +#define preempt_enable_no_resched_notrace() barrier() +#define preempt_enable_notrace() barrier() +#define preempt_check_resched_rt() barrier() + +#endif /* CONFIG_PREEMPT_COUNT */ + +#ifdef MODULE +/* + * Modules have no business playing preemption tricks. + */ +#undef sched_preempt_enable_no_resched +#undef preempt_enable_no_resched +#undef preempt_enable_no_resched_notrace +#undef preempt_check_resched +#endif + +#define preempt_set_need_resched() \ +do { \ + set_preempt_need_resched(); \ +} while (0) +#define preempt_fold_need_resched() \ +do { \ + if (tif_need_resched_now()) \ + set_preempt_need_resched(); \ +} while (0) + +#ifdef CONFIG_PREEMPT_RT_FULL +# define preempt_disable_rt() preempt_disable() +# define preempt_enable_rt() preempt_enable() +# define preempt_disable_nort() barrier() +# define preempt_enable_nort() barrier() +# ifdef CONFIG_SMP + extern void migrate_disable(void); + extern void migrate_enable(void); +# else /* CONFIG_SMP */ +# define migrate_disable() barrier() +# define migrate_enable() barrier() +# endif /* CONFIG_SMP */ +#else +# define preempt_disable_rt() barrier() +# define preempt_enable_rt() barrier() +# define preempt_disable_nort() preempt_disable() +# define preempt_enable_nort() preempt_enable() +# define migrate_disable() preempt_disable() +# define migrate_enable() preempt_enable() +#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 + * + * Please note that sched_in and out are called under different + * contexts. sched_out is called with rq lock held and irq disabled + * while sched_in is called without rq lock and irq enabled. This + * difference is intentional and depended upon by its users. + */ +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 */ |