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 8BFDBC43602 for ; Mon, 6 Jul 2026 17:22:14 +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=yJdgqDKy9noAujFzI15XGvq1vv/PVTlDEePaTlGp2bc=; b=uufQbEh+fR1Mga2cK+1RGFWUuW DTfzcNObo8c23jLGBjQzV0qk3TBmqKaYPLi3/KVqKCBCub0voIWdnpY3WjtLTflvMy5kPf7EVmpYi VPg+C3qVHhL11tfKwuNAWxc7aUwA4SmT9SDpXHGPZvxmUa6YLelDm1YcPgkY8LmcBFLR5iv6JS0+Z xgceP+GoBl+EgKQJXdNHR/NkK2JVKIuv4M3116s5JmgShtedqfaCOWJNGuZ7BOCzdkc21LHBrrjKa M6eZU4WAH+eKvq4hSm5Vv3ZDkg/ZSKwqNzmTtIEYbJ98OcDopFI8froLQBKiJ2b1+H0eC94jxuXUh qcfg5JeA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wgn1D-0000000DBcE-2mbZ; Mon, 06 Jul 2026 17:22:07 +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 1wgn1B-0000000DBbq-2Osl for linux-arm-kernel@lists.infradead.org; Mon, 06 Jul 2026 17:22:06 +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 06E25202C; Mon, 6 Jul 2026 10:21:58 -0700 (PDT) Received: from localhost (unknown [10.2.196.114]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id E69B33F7B4; Mon, 6 Jul 2026 10:22:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1783358522; bh=nyXnpvP+SrFs+sXW8UI4Gim+ItFWKgXrvSGiRoFfJI8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=XANEA5IPRVjLaDVcD1WSSxBvlGsiecrmqiQDqh+hiHHQjqy9QEZYkHMIgxKXYIeCV WgzbvUFNRxo9SaaZWIoVE26rJZzefTc7S1/q808i42nGkw9yM0+qsIqx0qQXDRJAMG NShlEomXFYzkpYk6u99FVSZsP2we0UH7ywNfwqhU= Date: Mon, 6 Jul 2026 18:21:59 +0100 From: Leo Yan To: Yeoreum Yun 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 v8 08/13] coresight: etm4x: fix inconsistencies with sysfs configuration Message-ID: <20260706172159.GA1024232@e132581.arm.com> References: <20260629090007.1718746-1-yeoreum.yun@arm.com> <20260629090007.1718746-9-yeoreum.yun@arm.com> MIME-Version: 1.0 Content-Type: text/plain; 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_102205_659892_5FA5D25D X-CRM114-Status: GOOD ( 14.78 ) 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: [...] > @@ -619,27 +622,52 @@ static int etm4_enable_hw(struct etmv4_drvdata *drvdata) > static void etm4_enable_sysfs_smp_call(void *info) > { > struct etm4_enable_arg *arg = info; > + struct etmv4_drvdata *drvdata; > struct coresight_device *csdev; > + unsigned long cfg_hash; > + int preset; > > if (WARN_ON(!arg)) > return; > > - csdev = arg->drvdata->csdev; > + drvdata = arg->drvdata; > + csdev = drvdata->csdev; > if (!coresight_take_mode(csdev, CS_MODE_SYSFS)) { > /* Someone is already using the tracer */ > arg->rc = -EBUSY; > return; > } > > - arg->rc = etm4_enable_hw(arg->drvdata); > + drvdata->active_config = arg->config; > > - /* The tracer didn't start */ > + /* enable any config activated by configfs */ > + cscfg_config_sysfs_get_active_cfg(&cfg_hash, &preset); > + if (cfg_hash) { > + arg->rc = cscfg_csdev_enable_active_config(csdev, > + cfg_hash, > + preset); > + if (arg->rc) > + goto err; > + } I try best to not paste any non-sense AI reviews, record one from Sashiko [1]: | If a user writes to a sysfs attribute like pe_sel_store(), it acquires | drvdata->spinlock without disabling interrupts. If an IPI is then handled | on the same CPU, etm4_enable_sysfs_smp_call() will call | cscfg_csdev_enable_active_config() which attempts to acquire the exact | same spinlock, hanging the CPU." The flow for acquiring drvdata->spinlock in SMP call is: etm4_enable_sysfs_smp_call() `> cscfg_csdev_enable_active_config() `> cscfg_csdev_enable_config() `> cscfg_prog_config() `> cscfg_set_on_enable() `> raw_spin_lock_irqsave(feat_csdev->drv_spinlock, flags); We might expect the complaint from LOCKDEP with this patch. To be clear, I am not object to this patch, just record in case we will handle it later. [1] https://sashiko.dev/#/patchset/20260629090007.1718746-1-yeoreum.yun%40arm.com