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 DDE0AF34C56 for ; Mon, 13 Apr 2026 14:20:28 +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:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=t/ITGBXb+6JlYkoLiD/k8mytDZiFQsgnSbtwtNFX5Zk=; b=FAbL4yl2NQNXrN0plJhcXIYQtb rwUNfgEb6RZwuQCh7X/DDLI77tzo1R53MG7h+9nDWrHEvvTQMf0wV+h4cTog5MDBKFcwmmhjJMTv7 dx1Pr8tbeUKSajP/cXzuTS6oW1OIYYoCxbrNN0fLfWW+kRNowEb9eXVtHJmgf/1yZd3A1knXPXjOw jCiaS3GBa2VkoEpOk/Lk4Ee8YvDocpsE4IKZe5/00M3gY8jbMWNBQY8G+n+uvTZmUdEY5qNQoX7Kj ehq53Ud4hIrf4qh6JtP5qODils7LjJEN1ZDRXI7V2CSF6t8qFmoUfkppjIRt7C5z39Z8CCz5EcbS0 qsOjPBzg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1wCI9G-0000000FqZZ-1WVH; Mon, 13 Apr 2026 14:20:22 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1wCI9A-0000000FqV2-3gr7 for linux-arm-kernel@lists.infradead.org; Mon, 13 Apr 2026 14:20:18 +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 948D0359A; Mon, 13 Apr 2026 07:20:10 -0700 (PDT) Received: from e129823.cambridge.arm.com (e129823.arm.com [10.1.197.6]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id BCE963F641; Mon, 13 Apr 2026 07:20:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1776090016; bh=c0st7JybrwCZbZ8ZJ6QIDs3+mz+WSuu30vMH4RaKehk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jRDdbwj09g2nOAbY8vKdO6xBXiPxmAs6Q5gxqxJEv1cJ/hdJyYFz+OgDX2boLBlUx /ZtVO1XdH+fttfXeR1FNSWY+v+YxL7T2HggzQ141uCv2QBXGyI+xdMTZ5SlNAz2wcM tjBQc1eyuueY5+1icJ7QJ2Y9Kutji/uxtXxfJSNs= From: Yeoreum Yun To: coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Cc: suzuki.poulose@arm.com, mike.leach@arm.com, james.clark@linaro.org, alexander.shishkin@linux.intel.com, leo.yan@arm.com, jie.gan@oss.qualcomm.com, Yeoreum Yun Subject: [PATCH v4 5/9] coresight: etm4x: remove redundant call etm4_enable_hw() with hotplug Date: Mon, 13 Apr 2026 15:19:58 +0100 Message-Id: <20260413142003.3549310-6-yeoreum.yun@arm.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260413142003.3549310-1-yeoreum.yun@arm.com> References: <20260413142003.3549310-1-yeoreum.yun@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260413_072016_962390_15C328F2 X-CRM114-Status: UNSURE ( 9.83 ) X-CRM114-Notice: Please train this message. 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 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(). To remove this redundant call, take the hotplug lock before executing etm4_enable_sysfs_smp_call(). Signed-off-by: Yeoreum Yun --- drivers/hwtracing/coresight/coresight-etm4x-core.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c index 01099689525b..facd5a306228 100644 --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c @@ -959,8 +959,20 @@ static int etm4_enable_sysfs(struct coresight_device *csdev, struct coresight_pa arg.config = drvdata->config; raw_spin_unlock(&drvdata->spinlock); + /* + * 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(); + if (!ret) ret = arg.rc; if (!ret) -- LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}