From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F1CA0C433F5 for ; Thu, 23 Sep 2021 16:54:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DBA206121F for ; Thu, 23 Sep 2021 16:54:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239695AbhIWQ4K (ORCPT ); Thu, 23 Sep 2021 12:56:10 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:35966 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233389AbhIWQ4I (ORCPT ); Thu, 23 Sep 2021 12:56:08 -0400 Message-ID: <20210923165357.928693482@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1632416076; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=ewd4pU+vwBo7kb7O/Zi1128ArMzkauCl+FkloHOqYe0=; b=jhmvAFq7AAotnBtVTWHvHTcvYtdLjbr5MdpVqwINbgk/Pxl7TY86kUHOoQ+nhLhiDQDF7Z lcI+8k9UnwQE8sZ4psuo+0Y3WXN4pciOdjzuWioXa7iKkoDI3TMVXfY+gtI1Toe9t2nE3e P9JF1yP9bRIhaQSXnEWhiPwK5QUjn8eCTc6a1yj7WBYDyei4OkQmwVlQTCSavMJCEpj543 58Ah/LXaTuu+PF5jOvCHi1ynFjuEofW5oju+xEzTYoDTZwXli57L3SABeJ6oYmbPkvB0B7 PrtL15orKhZAGldSSyRgpRGuC+9mLAWnytEPKgJCF3DFIQfuxz2hv4SzYwi2tA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1632416076; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=ewd4pU+vwBo7kb7O/Zi1128ArMzkauCl+FkloHOqYe0=; b=03kNRFRdIf0bGQObGAHR40HfsP/1FEkIkGbuwJxrbKsNyvcpIrkcJasoluwfCFs2qsyjKX 6IpiCzbnrt9yiVDw== From: Thomas Gleixner To: LKML Cc: Peter Zijlstra , Ingo Molnar , Paul McKenney , Sebastian Siewior Subject: [patch 1/8] sched: Clean up the might_sleep() underscore zoo References: <20210923164145.466686140@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Date: Thu, 23 Sep 2021 18:54:35 +0200 (CEST) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org __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 --- 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) {