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[2620:137:e000::3:8]) by mx.google.com with ESMTPS id na4-20020a17090b4c0400b00263c23a5693si6576144pjb.13.2023.10.07.08.13.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 07 Oct 2023 08:13:37 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:8 as permitted sender) client-ip=2620:137:e000::3:8; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=k20201202 header.b=kIzj7hK0; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:8 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: from out1.vger.email (depot.vger.email [IPv6:2620:137:e000::3:0]) by fry.vger.email (Postfix) with ESMTP id 4171F8043069; Sat, 7 Oct 2023 08:13:35 -0700 (PDT) X-Virus-Status: Clean X-Virus-Scanned: clamav-milter 0.103.10 at fry.vger.email Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343946AbjJGPK3 (ORCPT + 99 others); Sat, 7 Oct 2023 11:10:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56050 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229824AbjJGPK2 (ORCPT ); Sat, 7 Oct 2023 11:10:28 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ED041B9; Sat, 7 Oct 2023 08:10:25 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 72083C433C8; Sat, 7 Oct 2023 15:10:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1696691425; bh=LH6IWkmyMSvjK2Q3N3HjTHI8GVBa4KuURUr6eXtccys=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=kIzj7hK0L/DbwMAVrxGzakiLql+kw3pXx1ew0g45ixAo3GNkeQrZzd9PuDWCWxF0Q 9IBOXzzVpCsDt4JbpDmYgKUBKpNX66jLsOOr9tVCZ3XSODwohF1YU51Wz+vb8VDu74 8Hmcp5ZInqFxhE0tUi7gjmR1snrHvZNqezzcM1Vyz/ZSBAYEgwoRvJzHA7kujsBVpi 2REy0U1jFFh3BGvyd+PmEiqEfNdsyDXsBeKG+hQKKqnvjFFCyUT799FTz4+7oUYpCo YaRyhio3Qc2+RS1XQBg66Gx7nlykEqJT67KZ7rKF79iuhooOR4XCaxgUXM4A8/t7Fp XhWS0vNlAW3HQ== Date: Sat, 7 Oct 2023 17:10:21 +0200 From: Simon Horman To: Chengfeng Ye Cc: jreuter@yaina.de, ralf@linux-mips.org, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, linux-hams@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH V2] ax25: Fix potential deadlock on &ax25_list_lock Message-ID: <20231007151021.GC831234@kernel.org> References: <20231005072349.52602-1-dg573847474@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20231005072349.52602-1-dg573847474@gmail.com> X-Spam-Status: No, score=2.4 required=5.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,MAILING_LIST_MULTI, RCVD_IN_SBL_CSS,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on fry.vger.email Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (fry.vger.email [0.0.0.0]); Sat, 07 Oct 2023 08:13:35 -0700 (PDT) X-Spam-Level: ** On Thu, Oct 05, 2023 at 07:23:49AM +0000, Chengfeng Ye wrote: > Timer interrupt ax25_ds_timeout() could introduce double locks on > &ax25_list_lock. > > ax25_ioctl() > --> ax25_ctl_ioctl() > --> ax25_dama_off() > --> ax25_dev_dama_off() > --> ax25_check_dama_slave() > --> spin_lock(&ax25_list_lock) > > --> ax25_ds_timeout() > --> spin_lock(&ax25_list_lock) > > This flaw was found by an experimental static analysis tool I am > developing for irq-related deadlock. > > To prevent the potential deadlock, the patch use spin_lock_bh() > on &ax25_list_lock inside ax25_check_dama_slave(). > > Fixes: c19c4b9c9acb ("[AX.25]: Optimize AX.25 socket list lock") > Signed-off-by: Chengfeng Ye Hi Chengfeng Ye, Are there other functions that spin_lock(&ax25_list_lock) that also need to use spin_lock_bh()? ...