linux-stable/include/asm-generic/preempt.h
Thomas Gleixner c1a280b68d sched/preempt: Use CONFIG_PREEMPTION where appropriate
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 <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20190726212124.117528401@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-07-31 19:03:34 +02:00

88 lines
1.9 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __ASM_PREEMPT_H
#define __ASM_PREEMPT_H
#include <linux/thread_info.h>
#define PREEMPT_ENABLED (0)
static __always_inline int preempt_count(void)
{
return READ_ONCE(current_thread_info()->preempt_count);
}
static __always_inline volatile int *preempt_count_ptr(void)
{
return &current_thread_info()->preempt_count;
}
static __always_inline void preempt_count_set(int pc)
{
*preempt_count_ptr() = pc;
}
/*
* must be macros to avoid header recursion hell
*/
#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 __always_inline void set_preempt_need_resched(void)
{
}
static __always_inline void clear_preempt_need_resched(void)
{
}
static __always_inline bool test_preempt_need_resched(void)
{
return false;
}
/*
* The various preempt_count add/sub methods
*/
static __always_inline void __preempt_count_add(int val)
{
*preempt_count_ptr() += val;
}
static __always_inline void __preempt_count_sub(int val)
{
*preempt_count_ptr() -= val;
}
static __always_inline bool __preempt_count_dec_and_test(void)
{
/*
* Because of load-store architectures cannot do per-cpu atomic
* operations; we cannot use PREEMPT_NEED_RESCHED because it might get
* lost.
*/
return !--*preempt_count_ptr() && tif_need_resched();
}
/*
* Returns true when we need to resched and can (barring IRQ state).
*/
static __always_inline bool should_resched(int preempt_offset)
{
return unlikely(preempt_count() == preempt_offset &&
tif_need_resched());
}
#ifdef CONFIG_PREEMPTION
extern asmlinkage void preempt_schedule(void);
#define __preempt_schedule() preempt_schedule()
extern asmlinkage void preempt_schedule_notrace(void);
#define __preempt_schedule_notrace() preempt_schedule_notrace()
#endif /* CONFIG_PREEMPTION */
#endif /* __ASM_PREEMPT_H */