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=-8.9 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 92402C282DD for ; Tue, 23 Apr 2019 06:25:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 618F4214AE for ; Tue, 23 Apr 2019 06:25:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="bbL/GmLL" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726320AbfDWGZb (ORCPT ); Tue, 23 Apr 2019 02:25:31 -0400 Received: from mail-pf1-f194.google.com ([209.85.210.194]:42264 "EHLO mail-pf1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725882AbfDWGZa (ORCPT ); Tue, 23 Apr 2019 02:25:30 -0400 Received: by mail-pf1-f194.google.com with SMTP id w25so6924913pfi.9 for ; Mon, 22 Apr 2019 23:25:30 -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=6XzPsxxN8b6uMru/eDEDCwc0UWRn8N/+CAQtdHTzt8M=; b=bbL/GmLLu4JeD4lq4jZjm7oRW/WpzAPSxEmpWqO8pht1URvea6+J+mA5uWSRk32uXJ 21tWMrAxUiEFbjHx/4QxAVYReVcElLPEZYEm9mnxseKePBMIOseBC88izQXEoIN4A7Il t3BbxBMfdIa4zfafVQ6+tDy9RIiJdqi2aZWjOoAemEhVtVg7DAGmqMW7qeiQDVp5JWSa c40K1ldJrJBMa4PPJGOMAqlEbma4RkMgKGdqPneROuj2/lxvdWue4jyaP50GfgxADtV/ hIuRUWTMdebDjc580ruwlPvnxIYx4Bmk/Bu5HQdvmRDmMF9KXDql+HzaUD3XYfDnG1VC 7IUA== 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=6XzPsxxN8b6uMru/eDEDCwc0UWRn8N/+CAQtdHTzt8M=; b=iGaWEdeu4WzZfAfBF1MyohN7s0Eu75a9IS9/bJiC2xno5Lh0N9+yRoGKLINB9rw5+Q 1eyeZ+AMdeRI9Q4/F2+kc8jno82eUGVwos+ZR05w9c0uQHhmAgTpFUDnnCYugCQA0w1P h1SBG57juRvszZdFKiwH2M2626qdsHE8ojothC7iRAImpFmMGm5EtapwuMQUA7WJqygm 2+mc06PUSVKBF0f4mG/omZPV44U8l5VVNb/lkEiWkrF7l7/a425UVtkcZEcUJN3J9Kbk cpy8Tnnt1AkBsuV5TlcH/HRFimcb20AATrjOhRow2omLQB/us8ouwx4uVzPOjFiwtTqo EP2Q== X-Gm-Message-State: APjAAAXu6XQnH4plp/Ig/TtpN2rNm/EWT9ZSgyGVI3z6B9xUWqUrbg0E YrKSj3K57rxuKofZwPPPeRg= X-Google-Smtp-Source: APXvYqwQVeiw+QMDbuCB20n+yM6NTy6IdIKvi4zEWFCzOUSCijljDUZFDZ0oysGFaDbh34nXB5rv/w== X-Received: by 2002:a62:6f47:: with SMTP id k68mr25148875pfc.196.1556000729939; Mon, 22 Apr 2019 23:25:29 -0700 (PDT) Received: from localhost.localdomain ([175.223.38.143]) by smtp.gmail.com with ESMTPSA id p3sm19490287pfn.167.2019.04.22.23.25.26 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 22 Apr 2019 23:25:29 -0700 (PDT) From: Sergey Senozhatsky X-Google-Original-From: Sergey Senozhatsky To: Petr Mladek , Steven Rostedt Cc: Andrew Morton , linux-kernel@vger.kernel.org, Sergey Senozhatsky , Sergey Senozhatsky Subject: [RFC][PATCH 2/2] printk: take console_sem when accessing console drivers list Date: Tue, 23 Apr 2019 15:25:11 +0900 Message-Id: <20190423062511.1118-3-sergey.senozhatsky@gmail.com> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190423062511.1118-1-sergey.senozhatsky@gmail.com> References: <20190423062511.1118-1-sergey.senozhatsky@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 We need to take console_sem lock when we iterate console drivers list. Otherwise, another CPU can concurrently modify console drivers list or console drivers. Signed-off-by: Sergey Senozhatsky --- kernel/printk/printk.c | 19 +++++++++++++------ 1 file changed, 13 insertions(+), 6 deletions(-) diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index b0e361ca1bea..c2bccf58d03e 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -2674,12 +2674,17 @@ void register_console(struct console *newcon) struct console_cmdline *c; static bool has_preferred; - if (console_drivers) - for_each_console(bcon) - if (WARN(bcon == newcon, - "console '%s%d' already registered\n", - bcon->name, bcon->index)) - return; + console_lock(); + if (console_drivers) { + for_each_console(bcon) { + if (bcon != newcon) + continue; + WARN(1, "console '%s%d' already registered\n", + bcon->name, bcon->index); + console_unlock(); + return; + } + } /* * before we register a new CON_BOOT console, make sure we don't @@ -2691,6 +2696,7 @@ void register_console(struct console *newcon) if (!(bcon->flags & CON_BOOT)) { pr_info("Too late to register bootconsole %s%d\n", newcon->name, newcon->index); + console_unlock(); return; } } @@ -2701,6 +2707,7 @@ void register_console(struct console *newcon) if (!has_preferred || bcon || !console_drivers) has_preferred = preferred_console >= 0; + console_unlock(); /* * See if we want to use this console driver. If we -- 2.21.0