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[209.132.183.28]) by mx.google.com with ESMTPS id f42si4122289qkh.191.2018.11.19.10.57.34 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 19 Nov 2018 10:57:34 -0800 (PST) From: Waiman Long Subject: [PATCH v2 08/17] locking/lockdep: Add support for nestable terminal locks Date: Mon, 19 Nov 2018 13:55:17 -0500 Message-Id: <1542653726-5655-9-git-send-email-longman@redhat.com> In-Reply-To: <1542653726-5655-1-git-send-email-longman@redhat.com> References: <1542653726-5655-1-git-send-email-longman@redhat.com> Sender: owner-linux-mm@kvack.org List-ID: To: Peter Zijlstra , Ingo Molnar , Will Deacon , Thomas Gleixner Cc: linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, linux-mm@kvack.org, iommu@lists.linux-foundation.org, Petr Mladek , Sergey Senozhatsky , Andrey Ryabinin , Tejun Heo , Andrew Morton , Waiman Long There are use cases where we want to allow nesting of one terminal lock underneath another terminal-like lock. That new lock type is called nestable terminal lock which can optionally allow the acquisition of no more than one regular (non-nestable) terminal lock underneath it. Signed-off-by: Waiman Long --- include/linux/lockdep.h | 9 ++++++++- kernel/locking/lockdep.c | 15 +++++++++++++-- kernel/locking/lockdep_internals.h | 2 +- 3 files changed, 22 insertions(+), 4 deletions(-) diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h index a146bca..b9435fb 100644 --- a/include/linux/lockdep.h +++ b/include/linux/lockdep.h @@ -148,16 +148,20 @@ struct lock_class_stats { * 1) LOCKDEP_FLAG_NOVALIDATE: No full validation, just simple checks. * 2) LOCKDEP_FLAG_TERMINAL: This is a terminal lock where lock/unlock on * another lock within its critical section is not allowed. + * 3) LOCKDEP_FLAG_TERMINAL_NESTABLE: This is a terminal lock that can + * allow one more regular terminal lock to be nested underneath it. * * Only the least significant 4 bits of the flags will be copied to the * held_lock structure. */ #define LOCKDEP_FLAG_TERMINAL (1 << 0) +#define LOCKDEP_FLAG_TERMINAL_NESTABLE (1 << 1) #define LOCKDEP_FLAG_NOVALIDATE (1 << 4) #define LOCKDEP_HLOCK_FLAGS_MASK 0x0f #define LOCKDEP_NOCHECK_FLAGS (LOCKDEP_FLAG_NOVALIDATE |\ - LOCKDEP_FLAG_TERMINAL) + LOCKDEP_FLAG_TERMINAL |\ + LOCKDEP_FLAG_TERMINAL_NESTABLE) /* * Map the lock object (the lock instance) to the lock-class object. @@ -327,6 +331,8 @@ extern void lockdep_init_map(struct lockdep_map *lock, const char *name, do { (lock)->dep_map.flags |= LOCKDEP_FLAG_NOVALIDATE; } while (0) #define lockdep_set_terminal_class(lock) \ do { (lock)->dep_map.flags |= LOCKDEP_FLAG_TERMINAL; } while (0) +#define lockdep_set_terminal_nestable_class(lock) \ + do { (lock)->dep_map.flags |= LOCKDEP_FLAG_TERMINAL_NESTABLE; } while (0) /* * Compare locking classes @@ -444,6 +450,7 @@ static inline void lockdep_on(void) #define lockdep_set_novalidate_class(lock) do { } while (0) #define lockdep_set_terminal_class(lock) do { } while (0) +#define lockdep_set_terminal_nestable_class(lock) do { } while (0) /* * We don't define lockdep_match_class() and lockdep_match_key() for !LOCKDEP diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 40894c1..5a853a6 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -3263,13 +3263,24 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass, class_idx = class - lock_classes + 1; if (depth) { + int prev_type; + hlock = curr->held_locks + depth - 1; /* - * Warn if the previous lock is a terminal lock. + * Warn if the previous lock is a terminal lock or the + * previous lock is a nestable terminal lock and the current + * one isn't a regular terminal lock. */ - if (DEBUG_LOCKS_WARN_ON(hlock_is_terminal(hlock))) + prev_type = hlock_is_terminal(hlock); + if (DEBUG_LOCKS_WARN_ON((prev_type == LOCKDEP_FLAG_TERMINAL) || + ((prev_type == LOCKDEP_FLAG_TERMINAL_NESTABLE) && + (flags_is_terminal(class->flags) != + LOCKDEP_FLAG_TERMINAL)))) { + pr_warn("Terminal lock error: prev lock = %s, curr lock = %s\n", + hlock->instance->name, class->name); return 0; + } if (hlock->class_idx == class_idx && nest_lock) { if (hlock->references) { diff --git a/kernel/locking/lockdep_internals.h b/kernel/locking/lockdep_internals.h index 271fba8..51fa141 100644 --- a/kernel/locking/lockdep_internals.h +++ b/kernel/locking/lockdep_internals.h @@ -215,5 +215,5 @@ static inline unsigned long debug_class_ops_read(struct lock_class *class) static inline unsigned int flags_is_terminal(unsigned int flags) { - return flags & LOCKDEP_FLAG_TERMINAL; + return flags & (LOCKDEP_FLAG_TERMINAL|LOCKDEP_FLAG_TERMINAL_NESTABLE); } -- 1.8.3.1