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https://github.com/torvalds/linux.git
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Thomas Gleixner
c1a280b68d
CONFIG_PREEMPTION is selected by CONFIG_PREEMPT and by CONFIG_PREEMPT_RT. Both PREEMPT and PREEMPT_RT require the same functionality which today depends on CONFIG_PREEMPT. Switch the preemption code, scheduler and init task over to use CONFIG_PREEMPTION. That's the first step towards RT in that area. The more complex changes are coming separately. Signed-off-by: Thomas Gleixner <[email protected]> Acked-by: Peter Zijlstra (Intel) <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Masami Hiramatsu <[email protected]> Cc: Paolo Bonzini <[email protected]> Cc: Paul E. McKenney <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Steven Rostedt <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]>
89 lines
1.9 KiB
C
89 lines
1.9 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __ASM_PREEMPT_H
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#define __ASM_PREEMPT_H
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#include <linux/thread_info.h>
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#define PREEMPT_ENABLED (0)
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static __always_inline int preempt_count(void)
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{
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return READ_ONCE(current_thread_info()->preempt_count);
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}
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static __always_inline volatile int *preempt_count_ptr(void)
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{
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return ¤t_thread_info()->preempt_count;
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}
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static __always_inline void preempt_count_set(int pc)
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{
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*preempt_count_ptr() = pc;
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}
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/*
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* must be macros to avoid header recursion hell
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*/
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#define init_task_preempt_count(p) do { \
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task_thread_info(p)->preempt_count = FORK_PREEMPT_COUNT; \
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} while (0)
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#define init_idle_preempt_count(p, cpu) do { \
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task_thread_info(p)->preempt_count = PREEMPT_ENABLED; \
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} while (0)
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static __always_inline void set_preempt_need_resched(void)
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{
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}
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static __always_inline void clear_preempt_need_resched(void)
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{
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}
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static __always_inline bool test_preempt_need_resched(void)
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{
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return false;
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}
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/*
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* The various preempt_count add/sub methods
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*/
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static __always_inline void __preempt_count_add(int val)
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{
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*preempt_count_ptr() += val;
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}
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static __always_inline void __preempt_count_sub(int val)
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{
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*preempt_count_ptr() -= val;
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}
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static __always_inline bool __preempt_count_dec_and_test(void)
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{
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/*
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* Because of load-store architectures cannot do per-cpu atomic
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* operations; we cannot use PREEMPT_NEED_RESCHED because it might get
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* lost.
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*/
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return !--*preempt_count_ptr() && tif_need_resched();
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}
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/*
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* Returns true when we need to resched and can (barring IRQ state).
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*/
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static __always_inline bool should_resched(int preempt_offset)
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{
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return unlikely(preempt_count() == preempt_offset &&
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tif_need_resched());
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}
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#ifdef CONFIG_PREEMPTION
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extern asmlinkage void preempt_schedule(void);
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#define __preempt_schedule() preempt_schedule()
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extern asmlinkage void preempt_schedule_notrace(void);
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#define __preempt_schedule_notrace() preempt_schedule_notrace()
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#endif /* CONFIG_PREEMPTION */
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#endif /* __ASM_PREEMPT_H */
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