The following commit has been merged into the sched/core branch of tip: Commit-ID: b965f1ddb47daa5b8b2e2bc9c921431236830367 Gitweb: https://git.kernel.org/tip/b965f1ddb47daa5b8b2e2bc9c921431236830367 Author: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> AuthorDate: Mon, 18 Jan 2021 15:12:20 +01:00 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitterDate: Wed, 17 Feb 2021 14:12:42 +01:00 preempt/dynamic: Provide cond_resched() and might_resched() static calls 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@xxxxxxxxxxxxx> Signed-off-by: Frederic Weisbecker <frederic@xxxxxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Link: https://lkml.kernel.org/r/20210118141223.123667-6-frederic@xxxxxxxxxx --- include/linux/kernel.h | 23 +++++++++++++++++++---- include/linux/sched.h | 27 ++++++++++++++++++++++++--- kernel/sched/core.c | 16 +++++++++++++--- 3 files changed, 56 insertions(+), 10 deletions(-) diff --git a/include/linux/kernel.h b/include/linux/kernel.h index f7902d8..cfd3d34 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -15,7 +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 <uapi/linux/kernel.h> @@ -81,11 +81,26 @@ 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); diff --git a/include/linux/sched.h b/include/linux/sched.h index e115222..2f35594 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -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); \ diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 4afbdd2..f7c8fd8 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6785,17 +6785,27 @@ 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 /*
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