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#else
jmp restore_all
#endif
ALIGN
handle_softirq:
#ifdef CONFIG_PREEMPT
cli
GET_CURRENT(%ebx)
incl preempt_count(%ebx)
sti
#endif
call SYMBOL_NAME(do_softirq)
jmp ret_from_intr
ALIGN
reschedule:
call SYMBOL_NAME(schedule) # test
jmp ret_from_sys_call
include/asm/hw_irq.h:
...
#ifdef CONFIG_PREEMPT
#define BUMP_CONTEX_SWITCH_LOCK \
GET_CURRENT \
"incl 4(%ebx)\n\t"
#else
#define BUMP_CONTEX_SWITCH_LOCK
#endif
#define SAVE_ALL \ 硬件中断保护入口现场
"cld\n\t" \
"pushl %es\n\t" \
"pushl %ds\n\t" \
"pushl %eax\n\t" \
"pushl %ebp\n\t" \
"pushl %edi\n\t" \
"pushl %esi\n\t" \
"pushl %edx\n\t" \
"pushl %ecx\n\t" \
"pushl %ebx\n\t" \
"movl $" STR(__KERNEL_DS) ",%edx\n\t" \
"movl %edx,%ds\n\t" \
"movl %edx,%es\n\t" \
BUMP_CONTEX_SWITCH_LOCK # 硬件中断的入口禁止内核抢占
include/Linux/spinlock.h:
#ifdef CONFIG_PREEMPT
#define switch_lock_count() current->preempt_count
#define in_ctx_sw_off() (switch_lock_count().counter) 判断当前进程的抢占计数
是否非零
#define atomic_ptr_in_ctx_sw_off() (&switch_lock_count())
#define ctx_sw_off() \ 禁止内核抢占
do { \
atomic_inc(atomic_ptr_in_ctx_sw_off()); \ 当前进程的内核抢占计数增1
} while (0)
#define ctx_sw_on_no_preempt() \ 允许内核抢占
do { \
atomic_dec(atomic_ptr_in_ctx_sw_off()); \ 当前进程的内核抢占计数减1
} while (0)
#define ctx_sw_on() \ 允许并完成内核抢占
do { \
if (atomic_dec_and_test(atomic_ptr_in_ctx_sw_off()) && \
current->need_resched) \
preempt_schedule(); \
} while (0)
#define spin_lock(lock) \
do { \
ctx_sw_off(); \ 进入自旋锁时禁止抢占
_raw_spin_lock(lock); \
} while(0)
#define spin_trylock(lock) ({ctx_sw_off(); _raw_spin_trylock(lock) ? \锁定并
测试原来是否上锁
1 : ({ctx_sw_on(); 0;});})
#define spin_unl上一页 [1] [2] [3] [4] [5] [6] 下一页 |
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