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Diffstat (limited to 'include/linux/preempt.h')
| -rw-r--r-- | include/linux/preempt.h | 155 |
1 files changed, 155 insertions, 0 deletions
diff --git a/include/linux/preempt.h b/include/linux/preempt.h new file mode 100644 index 00000000..5a710b9c --- /dev/null +++ b/include/linux/preempt.h @@ -0,0 +1,155 @@ +#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/thread_info.h> +#include <linux/linkage.h> +#include <linux/list.h> + +#if defined(CONFIG_DEBUG_PREEMPT) || defined(CONFIG_PREEMPT_TRACER) + extern void add_preempt_count(int val); + extern void sub_preempt_count(int val); +#else +# define add_preempt_count(val) do { preempt_count() += (val); } while (0) +# define sub_preempt_count(val) do { preempt_count() -= (val); } while (0) +#endif + +#define inc_preempt_count() add_preempt_count(1) +#define dec_preempt_count() sub_preempt_count(1) + +#define preempt_count() (current_thread_info()->preempt_count) + +#ifdef CONFIG_PREEMPT + +asmlinkage void preempt_schedule(void); + +#define preempt_check_resched() \ +do { \ + if (unlikely(test_thread_flag(TIF_NEED_RESCHED))) \ + preempt_schedule(); \ +} while (0) + +#else /* !CONFIG_PREEMPT */ + +#define preempt_check_resched() do { } while (0) + +#endif /* CONFIG_PREEMPT */ + + +#ifdef CONFIG_PREEMPT_COUNT + +#define preempt_disable() \ +do { \ + inc_preempt_count(); \ + barrier(); \ +} while (0) + +#define sched_preempt_enable_no_resched() \ +do { \ + barrier(); \ + dec_preempt_count(); \ +} while (0) + +#define preempt_enable_no_resched() sched_preempt_enable_no_resched() + +#define preempt_enable() \ +do { \ + preempt_enable_no_resched(); \ + barrier(); \ + preempt_check_resched(); \ +} while (0) + +/* For debugging and tracer internals only! */ +#define add_preempt_count_notrace(val) \ + do { preempt_count() += (val); } while (0) +#define sub_preempt_count_notrace(val) \ + do { preempt_count() -= (val); } while (0) +#define inc_preempt_count_notrace() add_preempt_count_notrace(1) +#define dec_preempt_count_notrace() sub_preempt_count_notrace(1) + +#define preempt_disable_notrace() \ +do { \ + inc_preempt_count_notrace(); \ + barrier(); \ +} while (0) + +#define preempt_enable_no_resched_notrace() \ +do { \ + barrier(); \ + dec_preempt_count_notrace(); \ +} while (0) + +/* preempt_check_resched is OK to trace */ +#define preempt_enable_notrace() \ +do { \ + preempt_enable_no_resched_notrace(); \ + barrier(); \ + preempt_check_resched(); \ +} while (0) + +#else /* !CONFIG_PREEMPT_COUNT */ + +#define preempt_disable() do { } while (0) +#define sched_preempt_enable_no_resched() do { } while (0) +#define preempt_enable_no_resched() do { } while (0) +#define preempt_enable() do { } while (0) + +#define preempt_disable_notrace() do { } while (0) +#define preempt_enable_no_resched_notrace() do { } while (0) +#define preempt_enable_notrace() do { } while (0) + +#endif /* CONFIG_PREEMPT_COUNT */ + +#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 */ |