Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753060AbdHJMZL (ORCPT ); Thu, 10 Aug 2017 08:25:11 -0400 Received: from terminus.zytor.com ([65.50.211.136]:36249 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752517AbdHJMZJ (ORCPT ); Thu, 10 Aug 2017 08:25:09 -0400 Date: Thu, 10 Aug 2017 05:21:30 -0700 From: tip-bot for Byungchul Park Message-ID: Cc: byungchul.park@lge.com, hpa@zytor.com, torvalds@linux-foundation.org, peterz@infradead.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@kernel.org Reply-To: byungchul.park@lge.com, hpa@zytor.com, torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, peterz@infradead.org, tglx@linutronix.de, mingo@kernel.org In-Reply-To: <1502089981-21272-10-git-send-email-byungchul.park@lge.com> References: <1502089981-21272-10-git-send-email-byungchul.park@lge.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:locking/core] locking/lockdep: Apply crossrelease to completions Git-Commit-ID: cd8084f91c02c1afd256a39aa833bff737631304 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5100 Lines: 163 Commit-ID: cd8084f91c02c1afd256a39aa833bff737631304 Gitweb: http://git.kernel.org/tip/cd8084f91c02c1afd256a39aa833bff737631304 Author: Byungchul Park AuthorDate: Mon, 7 Aug 2017 16:12:56 +0900 Committer: Ingo Molnar CommitDate: Thu, 10 Aug 2017 12:29:10 +0200 locking/lockdep: Apply crossrelease to completions Although wait_for_completion() and its family can cause deadlock, the lock correctness validator could not be applied to them until now, because things like complete() are usually called in a different context from the waiting context, which violates lockdep's assumption. Thanks to CONFIG_LOCKDEP_CROSSRELEASE, we can now apply the lockdep detector to those completion operations. Applied it. Signed-off-by: Byungchul Park Signed-off-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: akpm@linux-foundation.org Cc: boqun.feng@gmail.com Cc: kernel-team@lge.com Cc: kirill@shutemov.name Cc: npiggin@gmail.com Cc: walken@google.com Cc: willy@infradead.org Link: http://lkml.kernel.org/r/1502089981-21272-10-git-send-email-byungchul.park@lge.com Signed-off-by: Ingo Molnar --- include/linux/completion.h | 45 ++++++++++++++++++++++++++++++++++++++++++++- kernel/sched/completion.c | 11 +++++++++++ lib/Kconfig.debug | 9 +++++++++ 3 files changed, 64 insertions(+), 1 deletion(-) diff --git a/include/linux/completion.h b/include/linux/completion.h index 5d5aaae..9bcebf5 100644 --- a/include/linux/completion.h +++ b/include/linux/completion.h @@ -9,6 +9,9 @@ */ #include +#ifdef CONFIG_LOCKDEP_COMPLETE +#include +#endif /* * struct completion - structure used to maintain state for a "completion" @@ -25,10 +28,50 @@ struct completion { unsigned int done; wait_queue_head_t wait; +#ifdef CONFIG_LOCKDEP_COMPLETE + struct lockdep_map_cross map; +#endif }; +#ifdef CONFIG_LOCKDEP_COMPLETE +static inline void complete_acquire(struct completion *x) +{ + lock_acquire_exclusive((struct lockdep_map *)&x->map, 0, 0, NULL, _RET_IP_); +} + +static inline void complete_release(struct completion *x) +{ + lock_release((struct lockdep_map *)&x->map, 0, _RET_IP_); +} + +static inline void complete_release_commit(struct completion *x) +{ + lock_commit_crosslock((struct lockdep_map *)&x->map); +} + +#define init_completion(x) \ +do { \ + static struct lock_class_key __key; \ + lockdep_init_map_crosslock((struct lockdep_map *)&(x)->map, \ + "(complete)" #x, \ + &__key, 0); \ + __init_completion(x); \ +} while (0) +#else +#define init_completion(x) __init_completion(x) +static inline void complete_acquire(struct completion *x) {} +static inline void complete_release(struct completion *x) {} +static inline void complete_release_commit(struct completion *x) {} +#endif + +#ifdef CONFIG_LOCKDEP_COMPLETE +#define COMPLETION_INITIALIZER(work) \ + { 0, __WAIT_QUEUE_HEAD_INITIALIZER((work).wait), \ + STATIC_CROSS_LOCKDEP_MAP_INIT("(complete)" #work, &(work)) } +#else #define COMPLETION_INITIALIZER(work) \ { 0, __WAIT_QUEUE_HEAD_INITIALIZER((work).wait) } +#endif #define COMPLETION_INITIALIZER_ONSTACK(work) \ ({ init_completion(&work); work; }) @@ -70,7 +113,7 @@ struct completion { * This inline function will initialize a dynamically created completion * structure. */ -static inline void init_completion(struct completion *x) +static inline void __init_completion(struct completion *x) { x->done = 0; init_waitqueue_head(&x->wait); diff --git a/kernel/sched/completion.c b/kernel/sched/completion.c index 13fc5ae..566b6ec 100644 --- a/kernel/sched/completion.c +++ b/kernel/sched/completion.c @@ -32,6 +32,12 @@ void complete(struct completion *x) unsigned long flags; spin_lock_irqsave(&x->wait.lock, flags); + + /* + * Perform commit of crossrelease here. + */ + complete_release_commit(x); + if (x->done != UINT_MAX) x->done++; __wake_up_locked(&x->wait, TASK_NORMAL, 1); @@ -92,9 +98,14 @@ __wait_for_common(struct completion *x, { might_sleep(); + complete_acquire(x); + spin_lock_irq(&x->wait.lock); timeout = do_wait_for_common(x, action, timeout, state); spin_unlock_irq(&x->wait.lock); + + complete_release(x); + return timeout; } diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index c6038f2..ebd40d3 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -1162,6 +1162,15 @@ config LOCKDEP_CROSSRELEASE such as page locks or completions can use the lock correctness detector, lockdep. +config LOCKDEP_COMPLETE + bool "Lock debugging: allow completions to use deadlock detector" + depends on PROVE_LOCKING + select LOCKDEP_CROSSRELEASE + default n + help + A deadlock caused by wait_for_completion() and complete() can be + detected by lockdep using crossrelease feature. + config DEBUG_LOCKDEP bool "Lock dependency engine debugging" depends on DEBUG_KERNEL && LOCKDEP