307 строки
8.6 KiB
C
307 строки
8.6 KiB
C
#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 put the hardirq and softirq counter into the preemption
|
|
* counter. The bitmask has the following meaning:
|
|
*
|
|
* - bits 0-7 are the preemption count (max preemption depth: 256)
|
|
* - bits 8-15 are the softirq count (max # of softirqs: 256)
|
|
*
|
|
* The hardirq count could in theory be the same as the number of
|
|
* interrupts in the system, but we run all interrupt handlers with
|
|
* interrupts disabled, so we cannot have nesting interrupts. Though
|
|
* there are a few palaeontologic drivers which reenable interrupts in
|
|
* the handler, so we need more than one bit here.
|
|
*
|
|
* PREEMPT_MASK: 0x000000ff
|
|
* SOFTIRQ_MASK: 0x0000ff00
|
|
* HARDIRQ_MASK: 0x000f0000
|
|
* NMI_MASK: 0x00100000
|
|
* PREEMPT_NEED_RESCHED: 0x80000000
|
|
*/
|
|
#define PREEMPT_BITS 8
|
|
#define SOFTIRQ_BITS 8
|
|
#define HARDIRQ_BITS 4
|
|
#define NMI_BITS 1
|
|
|
|
#define PREEMPT_SHIFT 0
|
|
#define SOFTIRQ_SHIFT (PREEMPT_SHIFT + PREEMPT_BITS)
|
|
#define HARDIRQ_SHIFT (SOFTIRQ_SHIFT + SOFTIRQ_BITS)
|
|
#define NMI_SHIFT (HARDIRQ_SHIFT + HARDIRQ_BITS)
|
|
|
|
#define __IRQ_MASK(x) ((1UL << (x))-1)
|
|
|
|
#define PREEMPT_MASK (__IRQ_MASK(PREEMPT_BITS) << PREEMPT_SHIFT)
|
|
#define SOFTIRQ_MASK (__IRQ_MASK(SOFTIRQ_BITS) << SOFTIRQ_SHIFT)
|
|
#define HARDIRQ_MASK (__IRQ_MASK(HARDIRQ_BITS) << HARDIRQ_SHIFT)
|
|
#define NMI_MASK (__IRQ_MASK(NMI_BITS) << NMI_SHIFT)
|
|
|
|
#define PREEMPT_OFFSET (1UL << PREEMPT_SHIFT)
|
|
#define SOFTIRQ_OFFSET (1UL << SOFTIRQ_SHIFT)
|
|
#define HARDIRQ_OFFSET (1UL << HARDIRQ_SHIFT)
|
|
#define NMI_OFFSET (1UL << NMI_SHIFT)
|
|
|
|
#define SOFTIRQ_DISABLE_OFFSET (2 * SOFTIRQ_OFFSET)
|
|
|
|
/* We use the MSB mostly because its available */
|
|
#define PREEMPT_NEED_RESCHED 0x80000000
|
|
|
|
/* preempt_count() and related functions, depends on PREEMPT_NEED_RESCHED */
|
|
#include <asm/preempt.h>
|
|
|
|
#define hardirq_count() (preempt_count() & HARDIRQ_MASK)
|
|
#define softirq_count() (preempt_count() & SOFTIRQ_MASK)
|
|
#define irq_count() (preempt_count() & (HARDIRQ_MASK | SOFTIRQ_MASK \
|
|
| NMI_MASK))
|
|
|
|
/*
|
|
* Are we doing bottom half or hardware interrupt processing?
|
|
*
|
|
* in_irq() - We're in (hard) IRQ context
|
|
* in_softirq() - We have BH disabled, or are processing softirqs
|
|
* in_interrupt() - We're in NMI,IRQ,SoftIRQ context or have BH disabled
|
|
* in_serving_softirq() - We're in softirq context
|
|
* in_nmi() - We're in NMI context
|
|
* in_task() - We're in task context
|
|
*
|
|
* Note: due to the BH disabled confusion: in_softirq(),in_interrupt() really
|
|
* should not be used in new code.
|
|
*/
|
|
#define in_irq() (hardirq_count())
|
|
#define in_softirq() (softirq_count())
|
|
#define in_interrupt() (irq_count())
|
|
#define in_serving_softirq() (softirq_count() & SOFTIRQ_OFFSET)
|
|
#define in_nmi() (preempt_count() & NMI_MASK)
|
|
#define in_task() (!(preempt_count() & \
|
|
(NMI_MASK | HARDIRQ_MASK | SOFTIRQ_OFFSET)))
|
|
|
|
/*
|
|
* The preempt_count offset after preempt_disable();
|
|
*/
|
|
#if defined(CONFIG_PREEMPT_COUNT)
|
|
# define PREEMPT_DISABLE_OFFSET PREEMPT_OFFSET
|
|
#else
|
|
# define PREEMPT_DISABLE_OFFSET 0
|
|
#endif
|
|
|
|
/*
|
|
* The preempt_count offset after spin_lock()
|
|
*/
|
|
#define PREEMPT_LOCK_OFFSET PREEMPT_DISABLE_OFFSET
|
|
|
|
/*
|
|
* The preempt_count offset needed for things like:
|
|
*
|
|
* spin_lock_bh()
|
|
*
|
|
* Which need to disable both preemption (CONFIG_PREEMPT_COUNT) and
|
|
* softirqs, such that unlock sequences of:
|
|
*
|
|
* spin_unlock();
|
|
* local_bh_enable();
|
|
*
|
|
* Work as expected.
|
|
*/
|
|
#define SOFTIRQ_LOCK_OFFSET (SOFTIRQ_DISABLE_OFFSET + PREEMPT_LOCK_OFFSET)
|
|
|
|
/*
|
|
* Are we running in atomic context? WARNING: this macro cannot
|
|
* always detect atomic context; in particular, it cannot know about
|
|
* held spinlocks in non-preemptible kernels. Thus it should not be
|
|
* used in the general case to determine whether sleeping is possible.
|
|
* Do not use in_atomic() in driver code.
|
|
*/
|
|
#define in_atomic() (preempt_count() != 0)
|
|
|
|
/*
|
|
* Check whether we were atomic before we did preempt_disable():
|
|
* (used by the scheduler)
|
|
*/
|
|
#define in_atomic_preempt_off() (preempt_count() != PREEMPT_DISABLE_OFFSET)
|
|
|
|
#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(0); })
|
|
#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()
|
|
|
|
#define preemptible() (preempt_count() == 0 && !irqs_disabled())
|
|
|
|
#ifdef CONFIG_PREEMPT
|
|
#define preempt_enable() \
|
|
do { \
|
|
barrier(); \
|
|
if (unlikely(preempt_count_dec_and_test())) \
|
|
__preempt_schedule(); \
|
|
} while (0)
|
|
|
|
#define preempt_enable_notrace() \
|
|
do { \
|
|
barrier(); \
|
|
if (unlikely(__preempt_count_dec_and_test())) \
|
|
__preempt_schedule_notrace(); \
|
|
} while (0)
|
|
|
|
#define preempt_check_resched() \
|
|
do { \
|
|
if (should_resched(0)) \
|
|
__preempt_schedule(); \
|
|
} while (0)
|
|
|
|
#else /* !CONFIG_PREEMPT */
|
|
#define preempt_enable() \
|
|
do { \
|
|
barrier(); \
|
|
preempt_count_dec(); \
|
|
} while (0)
|
|
|
|
#define preempt_enable_notrace() \
|
|
do { \
|
|
barrier(); \
|
|
__preempt_count_dec(); \
|
|
} while (0)
|
|
|
|
#define preempt_check_resched() do { } while (0)
|
|
#endif /* CONFIG_PREEMPT */
|
|
|
|
#define preempt_disable_notrace() \
|
|
do { \
|
|
__preempt_count_inc(); \
|
|
barrier(); \
|
|
} while (0)
|
|
|
|
#define preempt_enable_no_resched_notrace() \
|
|
do { \
|
|
barrier(); \
|
|
__preempt_count_dec(); \
|
|
} while (0)
|
|
|
|
#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 preemptible() 0
|
|
|
|
#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()) \
|
|
set_preempt_need_resched(); \
|
|
} while (0)
|
|
|
|
#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_inc(void);
|
|
void preempt_notifier_dec(void);
|
|
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 */
|