Commit 9253d578 authored by Peter Zijlstra (Intel)'s avatar Peter Zijlstra (Intel) Committed by Zheng Zengkai
Browse files

preempt/dynamic: Provide cond_resched() and might_resched() static calls 

mainline inclusion
from mainline-5.12-rc1
commit b965f1dd
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I410UT
CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b965f1ddb47daa5b8b2e2bc9c921431236830367



---------------------------

Provide static calls to control cond_resched() (called in !CONFIG_PREEMPT)
and might_resched() (called in CONFIG_PREEMPT_VOLUNTARY) to that we
can override their behaviour when preempt= is overriden.

Since the default behaviour is full preemption, both their calls are
ignored when preempt= isn't passed.

  [fweisbec: branch might_resched() directly to __cond_resched(), only
             define static calls when PREEMPT_DYNAMIC]

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarFrederic Weisbecker <frederic@kernel.org>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20210118141223.123667-6-frederic@kernel.org


Signed-off-by: default avatarMa Junhai <majunhai2@huawei.com>

 Conflicts:
	include/linux/kernel.h
Reviewed-by: default avatarChen Hui <judy.chenhui@huawei.com>

Signed-off-by: default avatarZheng Zengkai <zhengzengkai@huawei.com>
parent 8893f628

include/linux/kernel.h

+19 −3
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ 
#include <linux/typecheck.h>

#include <linux/printk.h>

#include <linux/build_bug.h>

#include <linux/static_call_types.h>

#include <asm/byteorder.h>

#include <asm/div64.h>

#include <uapi/linux/kernel.h>
@@ -194,11 +195,26 @@ struct pt_regs; 
struct user;



#ifdef CONFIG_PREEMPT_VOLUNTARY

extern int _cond_resched(void);

# define might_resched() _cond_resched()



extern int __cond_resched(void);

# define might_resched() __cond_resched()



#elif defined(CONFIG_PREEMPT_DYNAMIC)



extern int __cond_resched(void);



DECLARE_STATIC_CALL(might_resched, __cond_resched);



static __always_inline void might_resched(void)

{

	static_call(might_resched)();

}



#else



# define might_resched() do { } while (0)

#endif



#endif /* CONFIG_PREEMPT_* */



#ifdef CONFIG_DEBUG_ATOMIC_SLEEP

extern void ___might_sleep(const char *file, int line, int preempt_offset);

include/linux/sched.h

+24 −3
Original line number Diff line number Diff line
@@ -1860,11 +1860,32 @@ static inline int test_tsk_need_resched(struct task_struct *tsk) 
 * value indicates whether a reschedule was done in fact.

 * cond_resched_lock() will drop the spinlock before scheduling,

 */

#ifndef CONFIG_PREEMPTION

extern int _cond_resched(void);

#if !defined(CONFIG_PREEMPTION) || defined(CONFIG_PREEMPT_DYNAMIC)

extern int __cond_resched(void);



#ifdef CONFIG_PREEMPT_DYNAMIC



DECLARE_STATIC_CALL(cond_resched, __cond_resched);



static __always_inline int _cond_resched(void)

{

	return static_call(cond_resched)();

}



#else



static inline int _cond_resched(void)

{

	return __cond_resched();

}



#endif /* CONFIG_PREEMPT_DYNAMIC */



#else



static inline int _cond_resched(void) { return 0; }

#endif



#endif /* !defined(CONFIG_PREEMPTION) || defined(CONFIG_PREEMPT_DYNAMIC) */



#define cond_resched() ({			\

	___might_sleep(__FILE__, __LINE__, 0);	\

kernel/sched/core.c

+13 −3
Original line number Diff line number Diff line
@@ -6115,17 +6115,27 @@ SYSCALL_DEFINE0(sched_yield) 
	return 0;

}



#ifndef CONFIG_PREEMPTION

int __sched _cond_resched(void)

#if !defined(CONFIG_PREEMPTION) || defined(CONFIG_PREEMPT_DYNAMIC)

int __sched __cond_resched(void)

{

	if (should_resched(0)) {

		preempt_schedule_common();

		return 1;

	}

#ifndef CONFIG_PREEMPT_RCU

	rcu_all_qs();

#endif

	return 0;

}

EXPORT_SYMBOL(_cond_resched);

EXPORT_SYMBOL(__cond_resched);

#endif



#ifdef CONFIG_PREEMPT_DYNAMIC

DEFINE_STATIC_CALL_RET0(cond_resched, __cond_resched);

EXPORT_STATIC_CALL(cond_resched);



DEFINE_STATIC_CALL_RET0(might_resched, __cond_resched);

EXPORT_STATIC_CALL(might_resched);

#endif



/*