From fd509f4cbacfc99381dcc9a830a06518151a0d85 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner <tglx@linutronix.de> Date: Thu, 23 Sep 2021 18:54:35 +0200 Subject: [PATCH 060/166] sched: Clean up the might_sleep() underscore zoo __might_sleep() vs. ___might_sleep() is hard to distinguish. Aside of that the three underscore variant is exposed to provide a checkpoint for rescheduling points which are distinct from blocking points. They are semantically a preemption point which means that scheduling is state preserving. A real blocking operation, e.g. mutex_lock(), wait*(), which cannot preserve a task state which is not equal to RUNNING. While technically blocking on a "sleeping" spinlock in RT enabled kernels falls into the voluntary scheduling category because it has to wait until the contended spin/rw lock becomes available, the RT lock substitution code can semantically be mapped to a voluntary preemption because the RT lock substitution code and the scheduler are providing mechanisms to preserve the task state and to take regular non-lock related wakeups into account. Rename ___might_sleep() to __might_resched() to make the distinction of these functions clear. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Link: https://lore.kernel.org/r/20210923165357.928693482@linutronix.de --- include/linux/kernel.h | 6 +++--- include/linux/sched.h | 8 ++++---- kernel/locking/spinlock_rt.c | 6 +++--- kernel/sched/core.c | 6 +++--- 4 files changed, 13 insertions(+), 13 deletions(-) Index: linux-5.15.32-rt39/include/linux/kernel.h =================================================================== @ linux-5.15.32-rt39/include/linux/kernel.h:114 @ static __always_inline void might_resche #endif /* CONFIG_PREEMPT_* */ #ifdef CONFIG_DEBUG_ATOMIC_SLEEP -extern void ___might_sleep(const char *file, int line, int preempt_offset); +extern void __might_resched(const char *file, int line, int preempt_offset); extern void __might_sleep(const char *file, int line, int preempt_offset); extern void __cant_sleep(const char *file, int line, int preempt_offset); extern void __cant_migrate(const char *file, int line); @ linux-5.15.32-rt39/include/linux/kernel.h:171 @ extern void __cant_migrate(const char *f */ # define non_block_end() WARN_ON(current->non_block_count-- == 0) #else - static inline void ___might_sleep(const char *file, int line, - int preempt_offset) { } + static inline void __might_resched(const char *file, int line, + int preempt_offset) { } static inline void __might_sleep(const char *file, int line, int preempt_offset) { } # define might_sleep() do { might_resched(); } while (0) Index: linux-5.15.32-rt39/include/linux/sched.h =================================================================== --- linux-5.15.32-rt39.orig/include/linux/sched.h +++ linux-5.15.32-rt39/include/linux/sched.h @ linux-5.15.32-rt39/include/linux/kernel.h:2060 @ static inline int _cond_resched(void) { #endif /* !defined(CONFIG_PREEMPTION) || defined(CONFIG_PREEMPT_DYNAMIC) */ #define cond_resched() ({ \ - ___might_sleep(__FILE__, __LINE__, 0); \ + __might_resched(__FILE__, __LINE__, 0); \ _cond_resched(); \ }) @ linux-5.15.32-rt39/include/linux/kernel.h:2068 @ extern int __cond_resched_lock(spinlock_ extern int __cond_resched_rwlock_read(rwlock_t *lock); extern int __cond_resched_rwlock_write(rwlock_t *lock); -#define cond_resched_lock(lock) ({ \ - ___might_sleep(__FILE__, __LINE__, PREEMPT_LOCK_OFFSET);\ - __cond_resched_lock(lock); \ +#define cond_resched_lock(lock) ({ \ + __might_resched(__FILE__, __LINE__, PREEMPT_LOCK_OFFSET); \ + __cond_resched_lock(lock); \ }) #define cond_resched_rwlock_read(lock) ({ \ Index: linux-5.15.32-rt39/kernel/locking/spinlock_rt.c =================================================================== --- linux-5.15.32-rt39.orig/kernel/locking/spinlock_rt.c +++ linux-5.15.32-rt39/kernel/locking/spinlock_rt.c @ linux-5.15.32-rt39/include/linux/kernel.h:35 @ static __always_inline void rtlock_lock( static __always_inline void __rt_spin_lock(spinlock_t *lock) { - ___might_sleep(__FILE__, __LINE__, 0); + __might_resched(__FILE__, __LINE__, 0); rtlock_lock(&lock->lock); rcu_read_lock(); migrate_disable(); @ linux-5.15.32-rt39/include/linux/kernel.h:213 @ EXPORT_SYMBOL(rt_write_trylock); void __sched rt_read_lock(rwlock_t *rwlock) { - ___might_sleep(__FILE__, __LINE__, 0); + __might_resched(__FILE__, __LINE__, 0); rwlock_acquire_read(&rwlock->dep_map, 0, 0, _RET_IP_); rwbase_read_lock(&rwlock->rwbase, TASK_RTLOCK_WAIT); rcu_read_lock(); @ linux-5.15.32-rt39/include/linux/kernel.h:223 @ EXPORT_SYMBOL(rt_read_lock); void __sched rt_write_lock(rwlock_t *rwlock) { - ___might_sleep(__FILE__, __LINE__, 0); + __might_resched(__FILE__, __LINE__, 0); rwlock_acquire(&rwlock->dep_map, 0, 0, _RET_IP_); rwbase_write_lock(&rwlock->rwbase, TASK_RTLOCK_WAIT); rcu_read_lock(); Index: linux-5.15.32-rt39/kernel/sched/core.c =================================================================== --- linux-5.15.32-rt39.orig/kernel/sched/core.c +++ linux-5.15.32-rt39/kernel/sched/core.c @ linux-5.15.32-rt39/include/linux/kernel.h:9526 @ void __might_sleep(const char *file, int (void *)current->task_state_change, (void *)current->task_state_change); - ___might_sleep(file, line, preempt_offset); + __might_resched(file, line, preempt_offset); } EXPORT_SYMBOL(__might_sleep); -void ___might_sleep(const char *file, int line, int preempt_offset) +void __might_resched(const char *file, int line, int preempt_offset) { /* Ratelimiting timestamp: */ static unsigned long prev_jiffy; @ linux-5.15.32-rt39/include/linux/kernel.h:9575 @ void ___might_sleep(const char *file, in dump_stack(); add_taint(TAINT_WARN, LOCKDEP_STILL_OK); } -EXPORT_SYMBOL(___might_sleep); +EXPORT_SYMBOL(__might_resched); void __cant_sleep(const char *file, int line, int preempt_offset) {