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

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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: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20210118141223.123667-6-frederic@kernel.org
This commit is contained in:
Peter Zijlstra (Intel)
2021-01-18 15:12:20 +01:00
committed by Ingo Molnar
parent 6ef869e064
commit b965f1ddb4
3 changed files with 56 additions and 10 deletions
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27
include/linux/sched.h
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@@ -1871,11 +1871,32 @@ 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); \