1 #ifndef __ASM_PREEMPT_H
2 #define __ASM_PREEMPT_H
5 #include <asm/percpu.h>
6 #include <linux/thread_info.h>
8 DECLARE_PER_CPU(int, __preempt_count
);
11 * We use the PREEMPT_NEED_RESCHED bit as an inverted NEED_RESCHED such
12 * that a decrement hitting 0 means we can and should reschedule.
14 #define PREEMPT_ENABLED (0 + PREEMPT_NEED_RESCHED)
17 * We mask the PREEMPT_NEED_RESCHED bit so as not to confuse all current users
18 * that think a non-zero value indicates we cannot preempt.
20 static __always_inline
int preempt_count(void)
22 return raw_cpu_read_4(__preempt_count
) & ~PREEMPT_NEED_RESCHED
;
25 static __always_inline
void preempt_count_set(int pc
)
27 raw_cpu_write_4(__preempt_count
, pc
);
31 * must be macros to avoid header recursion hell
33 #define init_task_preempt_count(p) do { } while (0)
35 #define init_idle_preempt_count(p, cpu) do { \
36 per_cpu(__preempt_count, (cpu)) = PREEMPT_ENABLED; \
40 * We fold the NEED_RESCHED bit into the preempt count such that
41 * preempt_enable() can decrement and test for needing to reschedule with a
44 * We invert the actual bit, so that when the decrement hits 0 we know we both
45 * need to resched (the bit is cleared) and can resched (no preempt count).
48 static __always_inline
void set_preempt_need_resched(void)
50 raw_cpu_and_4(__preempt_count
, ~PREEMPT_NEED_RESCHED
);
53 static __always_inline
void clear_preempt_need_resched(void)
55 raw_cpu_or_4(__preempt_count
, PREEMPT_NEED_RESCHED
);
58 static __always_inline
bool test_preempt_need_resched(void)
60 return !(raw_cpu_read_4(__preempt_count
) & PREEMPT_NEED_RESCHED
);
64 * The various preempt_count add/sub methods
67 static __always_inline
void __preempt_count_add(int val
)
69 raw_cpu_add_4(__preempt_count
, val
);
72 static __always_inline
void __preempt_count_sub(int val
)
74 raw_cpu_add_4(__preempt_count
, -val
);
78 * Because we keep PREEMPT_NEED_RESCHED set when we do _not_ need to reschedule
79 * a decrement which hits zero means we have no preempt_count and should
82 static __always_inline
bool __preempt_count_dec_and_test(void)
84 GEN_UNARY_RMWcc("decl", __preempt_count
, __percpu_arg(0), "e");
88 * Returns true when we need to resched and can (barring IRQ state).
90 static __always_inline
bool should_resched(int preempt_offset
)
92 return unlikely(raw_cpu_read_4(__preempt_count
) == preempt_offset
);
96 extern asmlinkage
void ___preempt_schedule(void);
97 # define __preempt_schedule() \
99 register void *__sp asm(_ASM_SP); \
100 asm volatile ("call ___preempt_schedule" : "+r"(__sp)); \
103 extern asmlinkage
void preempt_schedule(void);
104 extern asmlinkage
void ___preempt_schedule_notrace(void);
105 # define __preempt_schedule_notrace() \
107 register void *__sp asm(_ASM_SP); \
108 asm volatile ("call ___preempt_schedule_notrace" : "+r"(__sp)); \
110 extern asmlinkage
void preempt_schedule_notrace(void);
113 #endif /* __ASM_PREEMPT_H */