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- #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_COUNT
- #define preempt_disable() \
- do { \
- preempt_count_inc(); \
- barrier(); \
- } while (0)
- #define sched_preempt_enable_no_resched() \
- do { \
- barrier(); \
- preempt_count_dec(); \
- } while (0)
- #define preempt_enable_no_resched() sched_preempt_enable_no_resched()
- #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)
- #else
- #define preempt_enable() preempt_enable_no_resched()
- #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() preempt_enable_no_resched_notrace()
- #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()
- #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 */
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