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 190EFC43458 for ; Mon, 6 Jul 2026 17:39:56 +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=9uBedfQnt54K3ZMGv2Ss49+XG5FadQKRRqu0gaUuWt0=; b=tyRoXm/bxeqKsI23sX/lfa0UAJ vSHC+KtsTSl1pIerjBqBWIESx1Rr+uwg3fFOvpgUIR0/Jykh0eT1EifmUL9tJVY3pVi7ciult69cf hhhurNCVuqTZxMTkHHjGq5dzqP4kITuzO9G0PdBcb28CxEJUyIvBL1XImDij5IY7oC7uBwLShuD2l kWpD0to+QHcVMoZJ0UZpTD+Z2j0F6LKxlq9J4W1CUl4t3VtXceiZFbTh7bby37dl7rfwloBJOvcmg Z7wQ7JImV0sb9WOKSlGjo7bWFq98yKVPeIlEzvhIUgm4fUYvulvJzICs0xfBrxN9QAjhXFuaSelSN ACgDkmVw==; 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charset=us-ascii Content-Disposition: inline In-Reply-To: <20260629090007.1718746-9-yeoreum.yun@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260706_103944_291613_EA0D59D0 X-CRM114-Status: GOOD ( 13.51 ) 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 On Mon, Jun 29, 2026 at 10:00:01AM +0100, Yeoreum Yun wrote: [...] > @@ -922,25 +950,7 @@ static int etm4_enable_sysfs(struct coresight_device *csdev, struct coresight_pa > { > struct etmv4_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent); > struct etm4_enable_arg arg = { }; > - unsigned long cfg_hash; > - int ret, preset; > - > - /* enable any config activated by configfs */ > - cscfg_config_sysfs_get_active_cfg(&cfg_hash, &preset); > - if (cfg_hash) { > - ret = cscfg_csdev_enable_active_config(csdev, cfg_hash, preset); > - if (ret) { > - etm4_release_trace_id(drvdata); > - return ret; > - } > - } > - > - raw_spin_lock(&drvdata->spinlock); > - > - drvdata->trcid = path->trace_id; > - > - /* Tracer will never be paused in sysfs mode */ > - drvdata->paused = false; > + int ret; > > /* > * Executing etm4_enable_hw on the cpu whose ETM is being enabled > @@ -948,20 +958,20 @@ static int etm4_enable_sysfs(struct coresight_device *csdev, struct coresight_pa > */ > arg.drvdata = drvdata; > arg.path = path; > + > + raw_spin_lock(&drvdata->spinlock); > + arg.config = drvdata->config; > + raw_spin_unlock(&drvdata->spinlock); > + > ret = smp_call_function_single(drvdata->cpu, > etm4_enable_sysfs_smp_call, &arg, 1); > if (!ret) > ret = arg.rc; > if (!ret) > - drvdata->sticky_enable = true; > - > - if (ret) > + dev_dbg(&csdev->dev, "ETM tracing enabled\n"); > + else > etm4_release_trace_id(drvdata); > > - raw_spin_unlock(&drvdata->spinlock); > - > - if (!ret) > - dev_dbg(&csdev->dev, "ETM tracing enabled\n"); > return ret; > } This is most valuable change for me, as now we will have much clear scope for what is protected ("drvdata->config"). However, a corner case was mentioned by Sashiko: | It appears etm4_enable_hw() modifies drvdata->ss_status while executing | via IPI, but sshot_ctrl_store() can modify the same array concurrently | from process context since the lock is no longer held across the | smp_call_function_single() call. "drvdata->ss_status" is a race condition between SMP call and sysfs knobs. Should we change to spinlock_irqsave/irqrestore when access drvdata->ss_status? Thanks, Leo