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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __ASM_PREEMPT_H
#define __ASM_PREEMPT_H
#include <linux/thread_info.h>
#define PREEMPT_NEED_RESCHED BIT(32)
#define PREEMPT_ENABLED (PREEMPT_NEED_RESCHED)
static inline int preempt_count(void)
{
return READ_ONCE(current_thread_info()->preempt.count);
}
static inline void preempt_count_set(u64 pc)
{
/* Preserve existing value of PREEMPT_NEED_RESCHED */
WRITE_ONCE(current_thread_info()->preempt.count, pc);
}
#define init_task_preempt_count(p) do { \
task_thread_info(p)->preempt_count = FORK_PREEMPT_COUNT; \
} while (0)
#define init_idle_preempt_count(p, cpu) do { \
task_thread_info(p)->preempt_count = PREEMPT_ENABLED; \
} while (0)
static inline void set_preempt_need_resched(void)
{
current_thread_info()->preempt.need_resched = 0;
}
static inline void clear_preempt_need_resched(void)
{
current_thread_info()->preempt.need_resched = 1;
}
static inline bool test_preempt_need_resched(void)
{
return !current_thread_info()->preempt.need_resched;
}
static inline void __preempt_count_add(int val)
{
u32 pc = READ_ONCE(current_thread_info()->preempt.count);
pc += val;
WRITE_ONCE(current_thread_info()->preempt.count, pc);
}
static inline void __preempt_count_sub(int val)
{
u32 pc = READ_ONCE(current_thread_info()->preempt.count);
pc -= val;
WRITE_ONCE(current_thread_info()->preempt.count, pc);
}
static inline bool __preempt_count_dec_and_test(void)
{
struct thread_info *ti = current_thread_info();
u64 pc = READ_ONCE(ti->preempt_count);
/* Update only the count field, leaving need_resched unchanged */
WRITE_ONCE(ti->preempt.count, --pc);
/*
* If we wrote back all zeroes, then we're preemptible and in
* need of a reschedule. Otherwise, we need to reload the
* preempt_count in case the need_resched flag was cleared by an
* interrupt occurring between the non-atomic READ_ONCE/WRITE_ONCE
* pair.
*/
if (!pc || !READ_ONCE(ti->preempt_count))
return true;
#ifdef CONFIG_PREEMPT_LAZY
if ((pc & ~PREEMPT_NEED_RESCHED))
return false;
if (current_thread_info()->preempt_lazy_count)
return false;
return test_thread_flag(TIF_NEED_RESCHED_LAZY);
#else
return false;
#endif
}
static inline bool should_resched(int preempt_offset)
{
#ifdef CONFIG_PREEMPT_LAZY
u64 pc = READ_ONCE(current_thread_info()->preempt_count);
if (pc == preempt_offset)
return true;
if ((pc & ~PREEMPT_NEED_RESCHED) != preempt_offset)
return false;
if (current_thread_info()->preempt_lazy_count)
return false;
return test_thread_flag(TIF_NEED_RESCHED_LAZY);
#else
u64 pc = READ_ONCE(current_thread_info()->preempt_count);
return pc == preempt_offset;
#endif
}
#ifdef CONFIG_PREEMPT
void preempt_schedule(void);
#define __preempt_schedule() preempt_schedule()
void preempt_schedule_notrace(void);
#define __preempt_schedule_notrace() preempt_schedule_notrace()
#endif /* CONFIG_PREEMPT */
#endif /* __ASM_PREEMPT_H */
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