forked from Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
322 lines
8.8 KiB
322 lines
8.8 KiB
#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? |
|
* Are we in a softirq context? Interrupt context? |
|
* in_softirq - Are we currently processing softirq or have bh disabled? |
|
* in_serving_softirq - Are we currently processing softirq? |
|
*/ |
|
#define in_irq() (hardirq_count()) |
|
#define in_softirq() (softirq_count()) |
|
#define in_interrupt() (irq_count()) |
|
#define in_serving_softirq() (softirq_count() & SOFTIRQ_OFFSET) |
|
|
|
/* |
|
* Are we in NMI context? |
|
*/ |
|
#define in_nmi() (preempt_count() & NMI_MASK) |
|
|
|
/* |
|
* 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 raw_preempt_count_add(val) __preempt_count_add(val) |
|
#define raw_preempt_count_sub(val) __preempt_count_sub(val) |
|
|
|
#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 raw_preempt_count_inc() raw_preempt_count_add(1) |
|
#define preempt_count_dec() preempt_count_sub(1) |
|
#define raw_preempt_count_dec() raw_preempt_count_sub(1) |
|
|
|
#ifdef CONFIG_PREEMPT_COUNT |
|
|
|
#define preempt_disable() \ |
|
do { \ |
|
preempt_count_inc(); \ |
|
barrier(); \ |
|
} while (0) |
|
|
|
#define raw_preempt_disable() \ |
|
do { \ |
|
raw_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 raw_preempt_enable_no_resched() \ |
|
do { \ |
|
barrier(); \ |
|
raw_preempt_count_dec(); \ |
|
} while (0) |
|
|
|
#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 raw_preempt_disable() barrier() |
|
#define sched_preempt_enable_no_resched() barrier() |
|
#define preempt_enable_no_resched() barrier() |
|
#define raw_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. |
|
*/ |
|
#ifndef CONFIG_PAX_KERNEXEC |
|
#undef sched_preempt_enable_no_resched |
|
#undef preempt_enable_no_resched |
|
#undef preempt_enable_no_resched_notrace |
|
#undef preempt_check_resched |
|
#endif |
|
#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 */
|
|
|