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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 21D5CCD4F25 for ; Fri, 15 May 2026 10:52:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=BsvKewNdj7IUFaN8tW/JH6YzfaLVipb7sTs8hNZNjn8=; b=Qp7rpCJJenkDtExq83TGIQDnqJ 2v5ptUVBuA0zqTcf9z6dAxI+d8aJKVT3Sr1CS3OBPDCJR3J4p7mBV4UDel+w82QdSJtSxHCf4wiLb KLAflNvpgmRQcJdD4lWBDgp7DREkOaEa6EeueHezFNBbnkLnL4U+1kqN2A9m3F/Tolomh4bcipSFL DgAoHsNPqQ2KrZp2dmf/9QrX8NdNTynfhmZXjaO8WiDzDw+cYS0ulrp12q39kLQN3tZGGrDMl1oGK yBSXEf6fNzvivMEuRK0Iqs659lGLsSv53DZNnIGFZ4pKpEZSAo4/wLxvoGhoCbLHydKL+f+qNp53Q jG9SxThg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wNq97-000000086FM-0Z7Y; Fri, 15 May 2026 10:51:57 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wNq92-000000086EZ-26vq for linux-arm-kernel@lists.infradead.org; Fri, 15 May 2026 10:51:55 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 808EC22FC; Fri, 15 May 2026 03:51:44 -0700 (PDT) Received: from e129823.arm.com (e129823.arm.com [10.1.197.6]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 35D7A3F7B4; Fri, 15 May 2026 03:51:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1778842309; bh=i308YaLa2XqUHgRFuI+4TbGQ5hu3AgLatwRRKeUrvJA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=rgpXdhSMfCVvXYdHIoyqKQO/oAJa0x3Do9b261C4yUGKt5pK+vETvn+gVykbIZ3gn uf+ZF9ECqK4xRIvVmNS76fzd7Pmb3LLA08/SCizCewZxcK//eA2cD3PCej2fUhgt3S qe+CiZ0ygBhVr9YK5ygKtsGVzmR+WdcMRdLED2M4= Date: Fri, 15 May 2026 11:51:44 +0100 From: Yeoreum Yun To: Leo Yan Cc: coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, suzuki.poulose@arm.com, mike.leach@arm.com, james.clark@linaro.org, alexander.shishkin@linux.intel.com, jie.gan@oss.qualcomm.com Subject: Re: [PATCH v6 08/13] coresight: etm4x: remove redundant call etm4_enable_hw() with hotplug Message-ID: References: <20260422132203.977549-1-yeoreum.yun@arm.com> <20260422132203.977549-9-yeoreum.yun@arm.com> <20260515090850.GI34802@e132581.arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260515090850.GI34802@e132581.arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260515_035152_666725_13C504D3 X-CRM114-Status: GOOD ( 14.88 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Leo, > On Wed, Apr 22, 2026 at 02:21:58PM +0100, Yeoreum Yun wrote: > > [...] > > > + /* > > + * Take the hotplug lock to prevent redundant calls to etm4_enable_hw(). > > + * > > + * The cpu_online_mask is set at the CPUHP_BRINGUP_CPU step. > > + * In other words, if etm4_enable_sysfs() is called between > > + * CPUHP_BRINGUP_CPU and CPUHP_AP_ARM_CORESIGHT_STARTING, > > + * etm4_enable_hw() may be invoked in etm4_enable_sysfs_smp_call() > > + * and then executed again in etm4_starting_cpu(). > > + */ > > + cpus_read_lock(); > > ret = smp_call_function_single(drvdata->cpu, > > etm4_enable_sysfs_smp_call, &arg, 1); > > + cpus_read_unlock(); > > This will cause double deadlock with the patch: > https://lore.kernel.org/linux-arm-kernel/20260511-arm_coresight_path_power_management_improvement-v12-6-1c9dcb1de8c9@arm.com/#t > > I think we need to drop this one. As I asked on another thread, Are we're going to merge your patch first? If not, we need to sustain it anyway. Thanks. -- Sincerely, Yeoreum Yun