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 19451C43458 for ; Tue, 7 Jul 2026 08:07:19 +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=D5hZ22QT8RyLsAdZuaKt1QczN1BYUT1xrNG23rF5y4k=; b=x6eNZg6iaAOP0uP216EVr/7dMh ne6Sipz5UxdRF5ISQ5gThzA0tKzHUszmHkhLzRzC2n5Hf+nH2Tt1P1GedObxkBgdunJk+0CZ8Xrlz wKjEasO4iJvDz8i32SBSlcCPLaR71uy1wJEN4832Xb0rvAxCaptXYAEipDr/0EewvbAiKaaURf28/ whQCWGjIofYt0RCFOns/jKLq3/e214yJi+OeSUNCmuBRc3JwS4bL5NVSAV+C+1VxzdC03YxWpDVfZ oG1S9ENvrhT90RQ1SVpoXiIrrNRYLCXAKkX8VbKhKoDI32pDkXMMo7VvQkYwsfE2YTuFV4QSsenSl LCUmfIeA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wh0pj-0000000EPpc-43IQ; Tue, 07 Jul 2026 08:07:11 +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 1wh0pg-0000000EPnl-1URU for linux-arm-kernel@lists.infradead.org; Tue, 07 Jul 2026 08:07:10 +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 1EAFF1BCA; Tue, 7 Jul 2026 01:07:02 -0700 (PDT) Received: from localhost (unknown [10.2.196.114]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id F345D3F85F; Tue, 7 Jul 2026 01:07:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1783411626; bh=sX5EZVB1oH6zpg7xImmTctzFiDXuMYq5ff7tEmh8srU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=BWSdSlSUWi/i+8R9Rwqt13/A4lRDyMQiKHmpd+S/MVokGklEgEtGj5nBElK3DzPer 00RuQT3IL8dsj29H0B4J5tr/8FDpz5BbRP9Y7F+KxQD0qFJmm1Q+1f0jk7Md4E6QNS m2eA6BqpBKqLTXVUuAGml7AfiY0BxMZ1bGdfTXSE= Date: Tue, 7 Jul 2026 09:07:03 +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: <20260707080703.GC1024232@e132581.arm.com> References: <20260629090007.1718746-1-yeoreum.yun@arm.com> <20260629090007.1718746-9-yeoreum.yun@arm.com> <20260706173940.GB1024232@e132581.arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260707_010708_663903_BF5FD125 X-CRM114-Status: GOOD ( 13.95 ) 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, Jul 06, 2026 at 07:20:48PM +0100, Yeoreum Yun wrote: [...] > > 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? > > I know this, but This is currently ignorable since > whatever perf or sysfs session, the ss_status is always clear > the PENDING and STATUS bits (and we make a compromise for this right now). > > And the sshot_ctrl_store()'s action is always clear above bits. > > So, This is ignorable comment from Sashiko. I understand it now, we can ignore it. Thanks for explanation.