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[2620:137:e000::3:7]) by mx.google.com with ESMTPS id e15-20020a17090301cf00b001c7264c45a6si5042075plh.563.2023.10.06.16.28.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 06 Oct 2023 16:28:42 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:7 as permitted sender) client-ip=2620:137:e000::3:7; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=k20201202 header.b=ezPcYymp; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:7 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 snail.vger.email (Postfix) with ESMTP id F2B2A82215EE; Fri, 6 Oct 2023 16:28:41 -0700 (PDT) X-Virus-Status: Clean X-Virus-Scanned: clamav-milter 0.103.10 at snail.vger.email Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233794AbjJFX2i (ORCPT + 99 others); Fri, 6 Oct 2023 19:28:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35006 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233692AbjJFX2h (ORCPT ); Fri, 6 Oct 2023 19:28:37 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C56CE93 for ; Fri, 6 Oct 2023 16:28:36 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id EB7EAC433C8; Fri, 6 Oct 2023 23:28:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1696634916; bh=f5eweFB5hd+xL6C7jrCKOvGvrLEavAJkP3G3+xCH9sg=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=ezPcYympZev/th+LBy9uF0GsqZCUFNQFiJNcub94b15mhHWP52Xg7V0T//Is3MdmH BT+Vvlp1nD8n/r64ZriB5nWBsRgM765u/CjF+9vw/pSHqtR5XGo1Xw09c9IcZ7FgU8 7W0rU/TBUnn2XY1ftVOC5Or4gevTjWzpO0vTYqAtZ2YfPzoLSsyVoGfwq3GB1HTXAr txpi2BajhHUjRK00GC/6iya7g9zdK2X8fddu+CRtfsMqqw4CvYflbo7qf/m/hViSMj u/j7hfiGHUdJn5hTZXD+T4LVkVFv3fLCFWFbDq5zigGGamxv+A7mLHYJR75Nhldjpf WfwoB2K+N2geA== Date: Fri, 6 Oct 2023 16:28:35 -0700 From: Jakub Kicinski To: Chengfeng Ye Cc: 3chas3@gmail.com, davem@davemloft.net, horms@kernel.org, linux-atm-general@lists.sourceforge.net, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 1/2] atm: solos-pci: Fix potential deadlock on &cli_queue_lock Message-ID: <20231006162835.79484017@kernel.org> In-Reply-To: <20231005074858.65082-1-dg573847474@gmail.com> References: <20231005074858.65082-1-dg573847474@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-4.4 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_MED, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net 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 (snail.vger.email [0.0.0.0]); Fri, 06 Oct 2023 16:28:42 -0700 (PDT) On Thu, 5 Oct 2023 07:48:58 +0000 Chengfeng Ye wrote: > As &card->cli_queue_lock is acquired under softirq context along the you say softirq here > following call chain from solos_bh(), other acquisition of the same > lock inside process context should disable at least bh to avoid double > lock. > > > console_show() > --> spin_lock(&card->cli_queue_lock) > > --> solos_bh() > --> spin_lock(&card->cli_queue_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 uses spin_lock_irqsave() > on the card->cli_queue_lock under process context code consistently > to prevent the possible deadlock scenario. and irqsave here. I think you're right that it's just softirq (== bh) that may deadlock, so no need to take the irqsave() version in process context. -- pw-bot: cr