From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 5403E46AF06 for ; Fri, 15 May 2026 10:51:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778842312; cv=none; b=avi3uEGdUEroyVL0MrZpaak2jJVOI1mUmrbLJNVmb7OQcQC9vhF2XkAZdJYwDtUscAWjyE6i/TTTUIhVeO88WjaV5NXfFtXlqpg78Lrpv2G3Za9s4ABn68Lmtkb691BowVjMs2/IvY2NFutIhVDLvbPdPpW0ZoTLh6xg2oHG7ck= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778842312; c=relaxed/simple; bh=i308YaLa2XqUHgRFuI+4TbGQ5hu3AgLatwRRKeUrvJA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=syhDyrqYhqiRiLJS4YADpVGPRMs2jZtlv+gQqjClsjPsVJD3+uBbISkHi34VR6YQygNNWDhhKsoRYZkl2lsqxtIu+tii/jhR8gwlLZEu+b7ht0KuAM5qXiA01ozd8Mlc46aPFieA4SEnH0aFm/TsfroCJbHSZ+3+ehOW+qXpMT0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=rgpXdhSM; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="rgpXdhSM" 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> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260515090850.GI34802@e132581.arm.com> 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