From: Thomas Gleixner <tglx@linutronix.de> To: LKML <linux-kernel@vger.kernel.org> Cc: Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@kernel.org>, Paul McKenney <paulmck@linux.vnet.ibm.com>, Sebastian Siewior <bigeasy@linutronix.de> Subject: [patch 1/8] sched: Clean up the might_sleep() underscore zoo Date: Thu, 23 Sep 2021 18:54:35 +0200 (CEST) [thread overview] Message-ID: <20210923165357.928693482@linutronix.de> (raw) In-Reply-To: <20210923164145.466686140@linutronix.de> __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> --- 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(-) --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -111,7 +111,7 @@ 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); @@ -168,8 +168,8 @@ 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) --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2041,7 +2041,7 @@ 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(); \ }) @@ -2049,9 +2049,9 @@ 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) ({ \ --- a/kernel/locking/spinlock_rt.c +++ b/kernel/locking/spinlock_rt.c @@ -32,7 +32,7 @@ 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(); @@ -210,7 +210,7 @@ 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(); @@ -220,7 +220,7 @@ 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(); --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -9446,11 +9446,11 @@ 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; @@ -9495,7 +9495,7 @@ 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) {
next prev parent reply other threads:[~2021-09-23 16:54 UTC|newest] Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-09-23 16:54 [patch 0/8] sched: Clean up might_sleep() and make it RT aware Thomas Gleixner 2021-09-23 16:54 ` Thomas Gleixner [this message] 2021-10-01 15:05 ` [tip: locking/core] sched: Clean up the might_sleep() underscore zoo tip-bot2 for Thomas Gleixner 2021-09-23 16:54 ` [patch 2/8] sched: Make cond_resched_*lock() variants consistent vs. might_sleep() Thomas Gleixner 2021-10-01 15:05 ` [tip: locking/core] " tip-bot2 for Thomas Gleixner 2021-09-23 16:54 ` [patch 3/8] sched: Remove preempt_offset argument from __might_sleep() Thomas Gleixner 2021-10-01 15:05 ` [tip: locking/core] " tip-bot2 for Thomas Gleixner 2021-09-23 16:54 ` [patch 4/8] sched: Cleanup might_sleep() printks Thomas Gleixner 2021-10-01 15:05 ` [tip: locking/core] " tip-bot2 for Thomas Gleixner 2021-09-23 16:54 ` [patch 5/8] sched: Make might_sleep() output less confusing Thomas Gleixner 2021-10-01 15:05 ` [tip: locking/core] " tip-bot2 for Thomas Gleixner 2021-09-23 16:54 ` [patch 6/8] sched: Make RCU nest depth distinct in __might_resched() Thomas Gleixner 2021-10-01 15:05 ` [tip: locking/core] " tip-bot2 for Thomas Gleixner 2021-09-23 16:54 ` [patch 7/8] sched: Make cond_resched_lock() variants RT aware Thomas Gleixner 2021-10-01 15:05 ` [tip: locking/core] " tip-bot2 for Thomas Gleixner 2021-09-23 16:54 ` [patch 8/8] locking/rt: Take RCU nesting into account for __might_resched() Thomas Gleixner 2021-10-01 15:05 ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
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