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=-9.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,HK_RANDOM_FROM,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 CFD43C04AB4 for ; Thu, 16 May 2019 08:00:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 992D0205C9 for ; Thu, 16 May 2019 08:00:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="mNebwHl3" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726787AbfEPIA2 (ORCPT ); Thu, 16 May 2019 04:00:28 -0400 Received: from mail-pf1-f194.google.com ([209.85.210.194]:34076 "EHLO mail-pf1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726363AbfEPIA1 (ORCPT ); Thu, 16 May 2019 04:00:27 -0400 Received: by mail-pf1-f194.google.com with SMTP id n19so1432185pfa.1 for ; Thu, 16 May 2019 01:00:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=PMKaB0Oa5QXUNtHyl3wAgOjSQCtL7tLwsVttCyl931A=; b=mNebwHl3556stsQHTW1xYb9i00Zjjy5fbFM+qBbXUliEAsVVZNhEhp43EmfV5B2vRU boj13OY5+UPXztGPhm7/ShGDQUa31xDy82gKWtqqMW9WKiGJPSQWKCRMBacgeePPiX0D 7Luyvc89GKpZSSl6avKi3kSoSqjM+PWsu3bp2nNnWjcBB3+RQSpTtoM+sJyFOpzJG8ck nUGQ+ALm2CV7GFzUFlPG9cTgGN+FxwrBvyQQiV1mcfuGI48LsDxtxu0foLo9Gpmi6p2k uAMSHbJM2u1sdn4JQwctG1AvLlggLkF7Y8h0niyJcuEmwWzbEuqq3b/IwfKwcNyOB3L7 i0DQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=PMKaB0Oa5QXUNtHyl3wAgOjSQCtL7tLwsVttCyl931A=; b=cxSqgkN8F6LydFcSh8zbd1wgIJMgV+BZzey9vnYiHS363w+1/hdC8wqv0EavvtOup8 uwA0CSJ615kH0C9uAlxjmUie4h2jHHBHMyFqgbF2zn6vTUBR5BkeNQBagFsugnQXqeav 5KtZGBANTkTCn5jofNoIM6dLaxmFXrh42dffWGov7FtfPv2eYrySSywSG34t7LryPKxO jAYxyMDkYWCVIMc71NwPQzMC+6I5WExgTk8LrOSggVtGSoUYYCuuT245SDagJLLqU0VV CsGvhVdQ73sVqLfMvrttep+wrYVlrWx3Crc36k0APusfDWcpUUmcP95OWtFz+Xpdpqal sfdA== X-Gm-Message-State: APjAAAWFD4KYwmSWqQcsg33XekbDQa8+tx6Q/FmLOW1xVj/EuhsP4LAv e1M8ixkqO3YgQHdVM9q9ekg= X-Google-Smtp-Source: APXvYqxEZ8uHgZrKQnzhJ3S8hHPZ19fsSPG0VvGau1UnOCbrzSS7e5qJNclF5RBz6uLZdeIS6WU5Ng== X-Received: by 2002:a63:17:: with SMTP id 23mr48293837pga.206.1557993626669; Thu, 16 May 2019 01:00:26 -0700 (PDT) Received: from localhost.localdomain ([203.100.54.194]) by smtp.gmail.com with ESMTPSA id p7sm2051471pgb.92.2019.05.16.01.00.23 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 16 May 2019 01:00:26 -0700 (PDT) From: Yuyang Du To: peterz@infradead.org, will.deacon@arm.com, mingo@kernel.org Cc: bvanassche@acm.org, ming.lei@redhat.com, frederic@kernel.org, tglx@linutronix.de, boqun.feng@gmail.com, paulmck@linux.ibm.com, linux-kernel@vger.kernel.org, Yuyang Du Subject: [PATCH v2 01/17] locking/lockdep: Add lock type enum to explicitly specify read or write locks Date: Thu, 16 May 2019 15:59:59 +0800 Message-Id: <20190516080015.16033-2-duyuyang@gmail.com> X-Mailer: git-send-email 2.20.1 (Apple Git-117) In-Reply-To: <20190516080015.16033-1-duyuyang@gmail.com> References: <20190516080015.16033-1-duyuyang@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add an enum to formalize lock types, as those type values now matter. In order to make: LOCK_TYPE_READ & LOCK_TYPE_RECURSIVE != 0 The recursive-read type is set to 3 as opposed to the current 2. Signed-off-by: Yuyang Du --- include/linux/lockdep.h | 45 +++++++++++++++++++++++++++++++++++++++------ include/linux/rcupdate.h | 2 +- kernel/locking/lockdep.c | 23 +++++++++++++---------- 3 files changed, 53 insertions(+), 17 deletions(-) diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h index 7c2fefa..1009c47 100644 --- a/include/linux/lockdep.h +++ b/include/linux/lockdep.h @@ -339,10 +339,38 @@ static inline int lockdep_match_key(struct lockdep_map *lock, * * Values for "read": * - * 0: exclusive (write) acquire - * 1: read-acquire (no recursion allowed) - * 2: read-acquire with same-instance recursion allowed + * LOCK_TYPE_EXCLUSIVE (LOCK_TYPE_WRITE): exclusive (write) acquire + * LOCK_TYPE_READ: read-acquire (no recursion allowed) + * LOCK_TYPE_RECURSIVE: read-acquire with same-instance recursion allowed * + * The same lock between tasks have the following exclusiveness (the read + * type includes recursive read): + * + * read and read (no ) + * read and write (yes) + * write and write (yes) + * + * The enum values for the types are arranged such that: + * + * if type1 and type2 are exclusive then type1 & type2 == 0. + * + * We have a tricky situation concerning read vs. recursive-read. Since + * there can be lock classes that may ever be both read lock and + * recursive-read lock, for example: + * + * kernel/qrwlock.c:queued_read_lock_slowpath() + * + * The values of lock types are defined as follows: + */ +enum lock_type { + LOCK_TYPE_EXCLUSIVE = 0, + LOCK_TYPE_WRITE = 0, + LOCK_TYPE_READ, + LOCK_TYPE_UNUSED, + LOCK_TYPE_RECURSIVE, +}; + +/* * Values for check: * * 0: simple checks (freeing, held-at-exit-time, etc.) @@ -588,9 +616,14 @@ static inline void print_irqtrace_events(struct task_struct *curr) * on the per lock-class debug mode: */ -#define lock_acquire_exclusive(l, s, t, n, i) lock_acquire(l, s, t, 0, 1, n, i) -#define lock_acquire_shared(l, s, t, n, i) lock_acquire(l, s, t, 1, 1, n, i) -#define lock_acquire_shared_recursive(l, s, t, n, i) lock_acquire(l, s, t, 2, 1, n, i) +#define lock_acquire_exclusive(l, s, t, n, i) \ + lock_acquire(l, s, t, LOCK_TYPE_EXCLUSIVE, 1, n, i) + +#define lock_acquire_shared(l, s, t, n, i) \ + lock_acquire(l, s, t, LOCK_TYPE_READ, 1, n, i) + +#define lock_acquire_shared_recursive(l, s, t, n, i) \ + lock_acquire(l, s, t, LOCK_TYPE_RECURSIVE, 1, n, i) #define spin_acquire(l, s, t, i) lock_acquire_exclusive(l, s, t, NULL, i) #define spin_acquire_nest(l, s, t, n, i) lock_acquire_exclusive(l, s, t, n, i) diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 922bb68..22b41b1 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -207,7 +207,7 @@ static inline void destroy_rcu_head_on_stack(struct rcu_head *head) { } static inline void rcu_lock_acquire(struct lockdep_map *map) { - lock_acquire(map, 0, 0, 2, 0, NULL, _THIS_IP_); + lock_acquire(map, 0, 0, LOCK_TYPE_RECURSIVE, 0, NULL, _THIS_IP_); } static inline void rcu_lock_release(struct lockdep_map *map) diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 7275d6c..fb6be63 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -2297,7 +2297,10 @@ static inline void inc_chains(void) * (Note that this has to be done separately, because the graph cannot * detect such classes of deadlocks.) * - * Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read + * Returns: + * 0: on deadlock detected; + * 1: on OK; + * 3: LOCK_TYPE_RECURSIVE on recursive read */ static int check_deadlock(struct task_struct *curr, struct held_lock *next) @@ -2319,15 +2322,15 @@ static inline void inc_chains(void) * Allow read-after-read recursion of the same * lock class (i.e. read_lock(lock)+read_lock(lock)): */ - if ((next->read == 2) && prev->read) - return 2; + if ((next->read == LOCK_TYPE_RECURSIVE) && prev->read) + return LOCK_TYPE_RECURSIVE; /* * We're holding the nest_lock, which serializes this lock's * nesting behaviour. */ if (nest) - return 2; + return LOCK_TYPE_RECURSIVE; print_deadlock_bug(curr, prev, next); return 0; @@ -2407,7 +2410,7 @@ static inline void inc_chains(void) * write-lock never takes any other locks, then the reads are * equivalent to a NOP. */ - if (next->read == 2 || prev->read == 2) + if (next->read == LOCK_TYPE_RECURSIVE || prev->read == LOCK_TYPE_RECURSIVE) return 1; /* * Is the -> dependency already present? @@ -2493,7 +2496,7 @@ static inline void inc_chains(void) * Only non-recursive-read entries get new dependencies * added: */ - if (hlock->read != 2 && hlock->check) { + if (hlock->read != LOCK_TYPE_RECURSIVE && hlock->check) { int ret = check_prev_add(curr, hlock, next, distance, &trace); if (!ret) @@ -2877,13 +2880,13 @@ static int validate_chain(struct task_struct *curr, * building dependencies (just like we jump over * trylock entries): */ - if (ret == 2) - hlock->read = 2; + if (ret == LOCK_TYPE_RECURSIVE) + hlock->read = LOCK_TYPE_RECURSIVE; /* * Add dependency only if this lock is not the head * of the chain, and if it's not a secondary read-lock: */ - if (!chain_head && ret != 2) { + if (!chain_head && ret != LOCK_TYPE_RECURSIVE) { if (!check_prevs_add(curr, hlock)) return 0; } @@ -4105,7 +4108,7 @@ static int __lock_downgrade(struct lockdep_map *lock, unsigned long ip) curr->curr_chain_key = hlock->prev_chain_key; WARN(hlock->read, "downgrading a read lock"); - hlock->read = 1; + hlock->read = LOCK_TYPE_READ; hlock->acquire_ip = ip; if (reacquire_held_locks(curr, depth, i)) -- 1.8.3.1