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=-8.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 2BA4FC04AAC for ; Mon, 6 May 2019 08:20:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EFD9D2082F for ; Mon, 6 May 2019 08:20:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Bfhbj1w3" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726621AbfEFIUj (ORCPT ); Mon, 6 May 2019 04:20:39 -0400 Received: from mail-pg1-f195.google.com ([209.85.215.195]:38809 "EHLO mail-pg1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726280AbfEFIUh (ORCPT ); Mon, 6 May 2019 04:20:37 -0400 Received: by mail-pg1-f195.google.com with SMTP id j26so6098092pgl.5 for ; Mon, 06 May 2019 01:20:37 -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=jncaqXpvY9xiIvXn8Y040qvm3yjppXEdYjg++AKhNVI=; b=Bfhbj1w36mqYHvEtPxZ35+PNe5TwYdL2vKfcb/A07W10m/xbYsCuKyHA/yBVWzbW+L q5XJ2gjjr/1KtCPv+kqyjdvkzmXGGFp/u364fSBV2o88zyo1f/oYtCRQDe21S9Bx4pvP Z6o8vkMXnH6xBVkGka8dMdungtRKcpoQNfdtHsTi9yBI9fdMWgqbt+jqKdnfZOcYJy0D yTraIc72PmejnyX6GUwODKqqKH6b0+HlRUmeqh/yPyA4TVHZjwJrKNGQs+ZjiYkm55M5 Zs9IJlNmSsxQNuvrMRlN8NzEwnTCpzMcW5GlW0shB4vFq6FHgLHow48/VQuqpqxijeUh oUoA== 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=jncaqXpvY9xiIvXn8Y040qvm3yjppXEdYjg++AKhNVI=; b=MPuK5nN5qX5UOdC35Tjh9n/cJTSLW0LSuEr9HJJqVinQ+C1BLNnxNS0dAAxmE2Ukon o23shFsEUlExDJhjuAzZTGfFmtA39dJ9wgwxexxpyKhyIsB0iggLn6vtZuWSncdvpYMu PS9DiVu37KjaDJ3zenTPEhSVcBe62r3NIQczIfFmMsh4LNM2BG6HY78RzLF9LdgCRKNZ 9mK+ZKmGoW0Qfatk5ws/M6e6Ie/9xP3rGuYOQIpjSXxiZ2VudC2vBDvNt4vRTtGOZXGm qmG5T/dA0dlLxh9lur8nj+rF/aTv0GgBGsSJyIdxGBWEv6RG2rGS4EXFPb9R6w++AP8O G9Mg== X-Gm-Message-State: APjAAAXOA1VwcDZFLlogAVhddH9Ee893NlyGrRMjHy/ehoQ8gTqn23/E KnM37oVXNXNhI9ZPohQEdyc= X-Google-Smtp-Source: APXvYqxWkQNMHLBnpH3eJiUDEizEP9HHCxgWNoS1q08/qPpbX4VMVs4tFGzmrL/5plTfrqfhDtuSmw== X-Received: by 2002:a62:5a42:: with SMTP id o63mr33025957pfb.170.1557130837029; Mon, 06 May 2019 01:20:37 -0700 (PDT) Received: from localhost.localdomain ([203.100.54.194]) by smtp.gmail.com with ESMTPSA id v19sm20958013pfa.138.2019.05.06.01.20.34 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 06 May 2019 01:20:36 -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, linux-kernel@vger.kernel.org, Yuyang Du Subject: [PATCH v2 15/23] locking/lockdep: Update comments on dependency search Date: Mon, 6 May 2019 16:19:31 +0800 Message-Id: <20190506081939.74287-16-duyuyang@gmail.com> X-Mailer: git-send-email 2.20.1 (Apple Git-117) In-Reply-To: <20190506081939.74287-1-duyuyang@gmail.com> References: <20190506081939.74287-1-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 The breadth-first search is implemented as flat-out non-recursive now, but the comments are still describing it as recursive, update the comments in that regard. Signed-off-by: Yuyang Du --- kernel/locking/lockdep.c | 21 ++++++++++----------- 1 file changed, 10 insertions(+), 11 deletions(-) diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 15cf2ac..7bd62e2 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -1376,6 +1376,10 @@ static inline struct list_head *get_dep_list(struct lock_list *lock, int offset) return lock_class + offset; } +/* + * Forward- or backward-dependency search, used for both circular dependency + * checking and hardirq-unsafe/softirq-unsafe checking. + */ static int __bfs(struct lock_list *source_entry, void *data, int (*match)(struct lock_list *entry, void *data), @@ -1456,12 +1460,6 @@ static inline int __bfs_backwards(struct lock_list *src_entry, } -/* - * Recursive, forwards-direction lock-dependency checking, used for - * both noncyclic checking and for hardirq-unsafe/softirq-unsafe - * checking. - */ - static void print_lock_trace(struct lock_trace *trace, unsigned int spaces) { unsigned long *entries = stack_trace + trace->offset; @@ -2280,7 +2278,7 @@ static inline void inc_chains(void) /* * There was a chain-cache miss, and we are about to add a new dependency - * to a previous lock. We recursively validate the following rules: + * to a previous lock. We validate the following rules: * * - would the adding of the -> dependency create a * circular dependency in the graph? [== circular deadlock] @@ -2330,11 +2328,12 @@ static inline void inc_chains(void) /* * Prove that the new -> dependency would not * create a circular dependency in the graph. (We do this by - * forward-recursing into the graph starting at , and - * checking whether we can reach .) + * a breadth-first search into the graph starting at , + * and check whether we can reach .) * - * We are using global variables to control the recursion, to - * keep the stackframe size of the recursive functions low: + * The search is limited by the size of the circular queue (i.e., + * MAX_CIRCULAR_QUEUE_SIZE) which keeps track of a breadth of nodes + * in the graph whose neighbours are to be checked. */ this.class = hlock_class(next); this.parent = NULL; -- 1.8.3.1