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[209.132.183.28]) by mx.google.com with ESMTPS id 190si957531qkk.28.2018.11.19.10.56.54 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 19 Nov 2018 10:56:54 -0800 (PST) Received-SPF: pass (google.com: domain of longman@redhat.com designates 209.132.183.28 as permitted sender) client-ip=209.132.183.28; Authentication-Results: mx.google.com; spf=pass (google.com: domain of longman@redhat.com designates 209.132.183.28 as permitted sender) smtp.mailfrom=longman@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 4D11573A85; Mon, 19 Nov 2018 18:56:53 +0000 (UTC) Received: from llong.com (dhcp-17-55.bos.redhat.com [10.18.17.55]) by smtp.corp.redhat.com (Postfix) with ESMTP id 73CCE608E7; Mon, 19 Nov 2018 18:56:51 +0000 (UTC) From: Waiman Long 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 Subject: [PATCH v2 02/17] locking/lockdep: Rework lockdep_set_novalidate_class() Date: Mon, 19 Nov 2018 13:55:11 -0500 Message-Id: <1542653726-5655-3-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> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Mon, 19 Nov 2018 18:56:53 +0000 (UTC) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: X-Virus-Scanned: ClamAV using ClamSMTP The current lockdep_set_novalidate_class() implementation is like a hack. It assigns a special class key for that lock and calls lockdep_init_map() twice. This patch changes the implementation to make it as a flag bit instead. This will allow other special locking class types to be defined and used in the lockdep code. A new "type" field is added to both the lockdep_map and lock_class structures. The new field can now be used to designate a lock and a class object as novalidate. The lockdep_set_novalidate_class() call, however, should be called only after lock initialization which calls lockdep_init_map(). For 64-bit architectures, the new type field won't increase the size of the lock_class structure. The lockdep_map structure won't change as well for 64-bit architectures with CONFIG_LOCK_STAT configured. Please note that lockdep_set_novalidate_class() should not be used at all unless there is overwhelming reason to do so. Hopefully we can retired it in the near future. Signed-off-by: Waiman Long --- include/linux/lockdep.h | 17 ++++++++++++++--- kernel/locking/lockdep.c | 14 +++++++------- 2 files changed, 21 insertions(+), 10 deletions(-) diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h index c5335df..8fe5b4f 100644 --- a/include/linux/lockdep.h +++ b/include/linux/lockdep.h @@ -58,8 +58,6 @@ struct lock_class_key { struct lockdep_subclass_key subkeys[MAX_LOCKDEP_SUBCLASSES]; }; -extern struct lock_class_key __lockdep_no_validate__; - #define LOCKSTAT_POINTS 4 /* @@ -94,6 +92,11 @@ struct lock_class { struct list_head locks_after, locks_before; /* + * Lock class type flags + */ + unsigned int flags; + + /* * Generation counter, when doing certain classes of graph walking, * to ensure that we check one node only once: */ @@ -140,6 +143,12 @@ struct lock_class_stats { #endif /* + * Lockdep class type flags + * 1) LOCKDEP_FLAG_NOVALIDATE: No full validation, just simple checks. + */ +#define LOCKDEP_FLAG_NOVALIDATE (1 << 0) + +/* * Map the lock object (the lock instance) to the lock-class object. * This is embedded into specific lock instances: */ @@ -147,6 +156,7 @@ struct lockdep_map { struct lock_class_key *key; struct lock_class *class_cache[NR_LOCKDEP_CACHING_CLASSES]; const char *name; + unsigned int flags; #ifdef CONFIG_LOCK_STAT int cpu; unsigned long ip; @@ -294,7 +304,8 @@ extern void lockdep_init_map(struct lockdep_map *lock, const char *name, (lock)->dep_map.key, sub) #define lockdep_set_novalidate_class(lock) \ - lockdep_set_class_and_name(lock, &__lockdep_no_validate__, #lock) + do { (lock)->dep_map.flags |= LOCKDEP_FLAG_NOVALIDATE; } while (0) + /* * Compare locking classes */ diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 1efada2..493b567 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -692,10 +692,11 @@ static int count_matching_names(struct lock_class *new_class) hlist_for_each_entry_rcu(class, hash_head, hash_entry) { if (class->key == key) { /* - * Huh! same key, different name? Did someone trample - * on some memory? We're most confused. + * Huh! same key, different name or flags? Did someone + * trample on some memory? We're most confused. */ - WARN_ON_ONCE(class->name != lock->name); + WARN_ON_ONCE((class->name != lock->name) || + (class->flags != lock->flags)); return class; } } @@ -788,6 +789,7 @@ static bool assign_lock_key(struct lockdep_map *lock) debug_atomic_inc(nr_unused_locks); class->key = key; class->name = lock->name; + class->flags = lock->flags; class->subclass = subclass; INIT_LIST_HEAD(&class->lock_entry); INIT_LIST_HEAD(&class->locks_before); @@ -3108,6 +3110,7 @@ static void __lockdep_init_map(struct lockdep_map *lock, const char *name, return; } + lock->flags = 0; lock->name = name; /* @@ -3152,9 +3155,6 @@ void lockdep_init_map(struct lockdep_map *lock, const char *name, } EXPORT_SYMBOL_GPL(lockdep_init_map); -struct lock_class_key __lockdep_no_validate__; -EXPORT_SYMBOL_GPL(__lockdep_no_validate__); - static int print_lock_nested_lock_not_held(struct task_struct *curr, struct held_lock *hlock, @@ -3215,7 +3215,7 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass, if (unlikely(!debug_locks)) return 0; - if (!prove_locking || lock->key == &__lockdep_no_validate__) + if (!prove_locking || (lock->flags & LOCKDEP_FLAG_NOVALIDATE)) check = 0; if (subclass < NR_LOCKDEP_CACHING_CLASSES)