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ba74c1448f
Create a distinction between scheduler related preempt_enable_no_resched() calls and the nearly one hundred other places in the kernel that do not want to reschedule, for one reason or another. This distinction matters for -rt, where the scheduler and the non-scheduler preempt models (and checks) are different. For upstream it's purely documentational. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/n/tip-gs88fvx2mdv5psnzxnv575ke@git.kernel.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
156 lines
4.1 KiB
C
156 lines
4.1 KiB
C
#ifndef __LINUX_PREEMPT_H
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#define __LINUX_PREEMPT_H
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/*
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* include/linux/preempt.h - macros for accessing and manipulating
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* preempt_count (used for kernel preemption, interrupt count, etc.)
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*/
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#include <linux/thread_info.h>
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#include <linux/linkage.h>
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#include <linux/list.h>
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#if defined(CONFIG_DEBUG_PREEMPT) || defined(CONFIG_PREEMPT_TRACER)
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extern void add_preempt_count(int val);
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extern void sub_preempt_count(int val);
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#else
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# define add_preempt_count(val) do { preempt_count() += (val); } while (0)
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# define sub_preempt_count(val) do { preempt_count() -= (val); } while (0)
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#endif
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#define inc_preempt_count() add_preempt_count(1)
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#define dec_preempt_count() sub_preempt_count(1)
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#define preempt_count() (current_thread_info()->preempt_count)
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#ifdef CONFIG_PREEMPT
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asmlinkage void preempt_schedule(void);
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#define preempt_check_resched() \
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do { \
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if (unlikely(test_thread_flag(TIF_NEED_RESCHED))) \
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preempt_schedule(); \
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} while (0)
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#else /* !CONFIG_PREEMPT */
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#define preempt_check_resched() do { } while (0)
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#endif /* CONFIG_PREEMPT */
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#ifdef CONFIG_PREEMPT_COUNT
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#define preempt_disable() \
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do { \
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inc_preempt_count(); \
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barrier(); \
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} while (0)
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#define sched_preempt_enable_no_resched() \
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do { \
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barrier(); \
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dec_preempt_count(); \
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} while (0)
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#define preempt_enable_no_resched() sched_preempt_enable_no_resched()
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#define preempt_enable() \
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do { \
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preempt_enable_no_resched(); \
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barrier(); \
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preempt_check_resched(); \
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} while (0)
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/* For debugging and tracer internals only! */
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#define add_preempt_count_notrace(val) \
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do { preempt_count() += (val); } while (0)
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#define sub_preempt_count_notrace(val) \
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do { preempt_count() -= (val); } while (0)
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#define inc_preempt_count_notrace() add_preempt_count_notrace(1)
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#define dec_preempt_count_notrace() sub_preempt_count_notrace(1)
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#define preempt_disable_notrace() \
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do { \
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inc_preempt_count_notrace(); \
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barrier(); \
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} while (0)
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#define preempt_enable_no_resched_notrace() \
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do { \
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barrier(); \
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dec_preempt_count_notrace(); \
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} while (0)
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/* preempt_check_resched is OK to trace */
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#define preempt_enable_notrace() \
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do { \
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preempt_enable_no_resched_notrace(); \
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barrier(); \
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preempt_check_resched(); \
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} while (0)
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#else /* !CONFIG_PREEMPT_COUNT */
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#define preempt_disable() do { } while (0)
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#define sched_preempt_enable_no_resched() do { } while (0)
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#define preempt_enable_no_resched() do { } while (0)
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#define preempt_enable() do { } while (0)
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#define preempt_disable_notrace() do { } while (0)
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#define preempt_enable_no_resched_notrace() do { } while (0)
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#define preempt_enable_notrace() do { } while (0)
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#endif /* CONFIG_PREEMPT_COUNT */
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#ifdef CONFIG_PREEMPT_NOTIFIERS
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struct preempt_notifier;
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/**
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* preempt_ops - notifiers called when a task is preempted and rescheduled
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* @sched_in: we're about to be rescheduled:
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* notifier: struct preempt_notifier for the task being scheduled
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* cpu: cpu we're scheduled on
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* @sched_out: we've just been preempted
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* notifier: struct preempt_notifier for the task being preempted
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* next: the task that's kicking us out
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*
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* Please note that sched_in and out are called under different
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* contexts. sched_out is called with rq lock held and irq disabled
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* while sched_in is called without rq lock and irq enabled. This
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* difference is intentional and depended upon by its users.
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*/
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struct preempt_ops {
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void (*sched_in)(struct preempt_notifier *notifier, int cpu);
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void (*sched_out)(struct preempt_notifier *notifier,
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struct task_struct *next);
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};
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/**
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* preempt_notifier - key for installing preemption notifiers
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* @link: internal use
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* @ops: defines the notifier functions to be called
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*
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* Usually used in conjunction with container_of().
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*/
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struct preempt_notifier {
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struct hlist_node link;
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struct preempt_ops *ops;
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};
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void preempt_notifier_register(struct preempt_notifier *notifier);
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void preempt_notifier_unregister(struct preempt_notifier *notifier);
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static inline void preempt_notifier_init(struct preempt_notifier *notifier,
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struct preempt_ops *ops)
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{
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INIT_HLIST_NODE(¬ifier->link);
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notifier->ops = ops;
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}
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#endif
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#endif /* __LINUX_PREEMPT_H */
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