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8cb75e0c4e
With various drivers wanting to inject idle time; we get people calling idle routines outside of the idle loop proper. Therefore we need to be extra careful about not missing TIF_NEED_RESCHED -> PREEMPT_NEED_RESCHED propagations. While looking at this, I also realized there's a small window in the existing idle loop where we can miss TIF_NEED_RESCHED; when it hits right after the tif_need_resched() test at the end of the loop but right before the need_resched() test at the start of the loop. So move preempt_fold_need_resched() out of the loop where we're guaranteed to have TIF_NEED_RESCHED set. Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/n/tip-x9jgh45oeayzajz2mjt0y7d6@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
201 lines
5.0 KiB
C
201 lines
5.0 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/linkage.h>
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#include <linux/list.h>
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/*
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* We use the MSB mostly because its available; see <linux/preempt_mask.h> for
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* the other bits -- can't include that header due to inclusion hell.
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*/
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#define PREEMPT_NEED_RESCHED 0x80000000
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#include <asm/preempt.h>
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#if defined(CONFIG_DEBUG_PREEMPT) || defined(CONFIG_PREEMPT_TRACER)
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extern void preempt_count_add(int val);
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extern void preempt_count_sub(int val);
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#define preempt_count_dec_and_test() ({ preempt_count_sub(1); should_resched(); })
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#else
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#define preempt_count_add(val) __preempt_count_add(val)
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#define preempt_count_sub(val) __preempt_count_sub(val)
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#define preempt_count_dec_and_test() __preempt_count_dec_and_test()
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#endif
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#define __preempt_count_inc() __preempt_count_add(1)
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#define __preempt_count_dec() __preempt_count_sub(1)
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#define preempt_count_inc() preempt_count_add(1)
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#define preempt_count_dec() preempt_count_sub(1)
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#ifdef CONFIG_PREEMPT_COUNT
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#define preempt_disable() \
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do { \
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preempt_count_inc(); \
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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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preempt_count_dec(); \
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} while (0)
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#define preempt_enable_no_resched() sched_preempt_enable_no_resched()
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#ifdef CONFIG_PREEMPT
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#define preempt_enable() \
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do { \
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barrier(); \
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if (unlikely(preempt_count_dec_and_test())) \
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__preempt_schedule(); \
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} while (0)
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#define preempt_check_resched() \
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do { \
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if (should_resched()) \
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__preempt_schedule(); \
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} while (0)
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#else
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#define preempt_enable() \
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do { \
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barrier(); \
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preempt_count_dec(); \
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} while (0)
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#define preempt_check_resched() do { } while (0)
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#endif
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#define preempt_disable_notrace() \
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do { \
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__preempt_count_inc(); \
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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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__preempt_count_dec(); \
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} while (0)
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#ifdef CONFIG_PREEMPT
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#ifndef CONFIG_CONTEXT_TRACKING
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#define __preempt_schedule_context() __preempt_schedule()
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#endif
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#define preempt_enable_notrace() \
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do { \
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barrier(); \
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if (unlikely(__preempt_count_dec_and_test())) \
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__preempt_schedule_context(); \
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} while (0)
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#else
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#define preempt_enable_notrace() \
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do { \
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barrier(); \
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__preempt_count_dec(); \
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} while (0)
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#endif
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#else /* !CONFIG_PREEMPT_COUNT */
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/*
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* Even if we don't have any preemption, we need preempt disable/enable
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* to be barriers, so that we don't have things like get_user/put_user
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* that can cause faults and scheduling migrate into our preempt-protected
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* region.
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*/
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#define preempt_disable() barrier()
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#define sched_preempt_enable_no_resched() barrier()
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#define preempt_enable_no_resched() barrier()
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#define preempt_enable() barrier()
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#define preempt_check_resched() do { } while (0)
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#define preempt_disable_notrace() barrier()
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#define preempt_enable_no_resched_notrace() barrier()
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#define preempt_enable_notrace() barrier()
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#endif /* CONFIG_PREEMPT_COUNT */
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#ifdef MODULE
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/*
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* Modules have no business playing preemption tricks.
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*/
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#undef sched_preempt_enable_no_resched
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#undef preempt_enable_no_resched
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#undef preempt_enable_no_resched_notrace
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#undef preempt_check_resched
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#endif
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#ifdef CONFIG_PREEMPT
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#define preempt_set_need_resched() \
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do { \
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set_preempt_need_resched(); \
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} while (0)
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#define preempt_fold_need_resched() \
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do { \
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if (tif_need_resched()) \
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set_preempt_need_resched(); \
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} while (0)
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#else
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#define preempt_set_need_resched() do { } while (0)
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#define preempt_fold_need_resched() do { } while (0)
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#endif
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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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