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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 544B5C3DA7A for ; Fri, 6 Jan 2023 16:43:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230514AbjAFQnn (ORCPT ); Fri, 6 Jan 2023 11:43:43 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57396 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233358AbjAFQm4 (ORCPT ); Fri, 6 Jan 2023 11:42:56 -0500 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 5A27A7A387 for ; Fri, 6 Jan 2023 08:41:46 -0800 (PST) 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 6FF4212FC; Fri, 6 Jan 2023 08:42:17 -0800 (PST) Received: from [10.57.45.115] (unknown [10.57.45.115]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 07CFD3F71A; Fri, 6 Jan 2023 08:41:33 -0800 (PST) Message-ID: <6e6272ae-1aff-335e-4390-09c7d522dd46@arm.com> Date: Fri, 6 Jan 2023 16:41:32 +0000 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.6.1 Subject: Re: [PATCH v2 1/3] coresight: cti: Prevent negative values of enable count To: James Clark , coresight@lists.linaro.org, quic_jinlmao@quicinc.com, mike.leach@linaro.org Cc: Mathieu Poirier , Leo Yan , Alexander Shishkin , Greg Kroah-Hartman , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <20230106152331.1374973-1-james.clark@arm.com> <20230106152331.1374973-2-james.clark@arm.com> From: Suzuki K Poulose In-Reply-To: <20230106152331.1374973-2-james.clark@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi James, Thanks for fixing this. On 06/01/2023 15:23, James Clark wrote: > Writing 0 to the enable control repeatedly results in a negative value > for enable_req_count. After this, writing 1 to the enable control > appears to not work until the count returns to positive. > > Change it so that it's impossible for enable_req_count to be < 0. I prefer rephrasing the following : > Returning an error will also allow us to decide whether to call > runtime_pm_put() or not in the following commit. "Return an error to indicate the disable request was invalid" and don't mention the forward dependency. > May be also add ? Fixes: 835d722ba10a ("coresight: cti: Initial CoreSight CTI Driver") > Signed-off-by: James Clark Rest looks fine to me. Suzuki > --- > drivers/hwtracing/coresight/coresight-cti-core.c | 11 +++++++++-- > 1 file changed, 9 insertions(+), 2 deletions(-) > > diff --git a/drivers/hwtracing/coresight/coresight-cti-core.c b/drivers/hwtracing/coresight/coresight-cti-core.c > index d2cf4f4848e1..838872f2484d 100644 > --- a/drivers/hwtracing/coresight/coresight-cti-core.c > +++ b/drivers/hwtracing/coresight/coresight-cti-core.c > @@ -151,9 +151,16 @@ static int cti_disable_hw(struct cti_drvdata *drvdata) > { > struct cti_config *config = &drvdata->config; > struct coresight_device *csdev = drvdata->csdev; > + int ret = 0; > > spin_lock(&drvdata->spinlock); > > + /* don't allow negative refcounts, return an error */ > + if (!atomic_read(&drvdata->config.enable_req_count)) { > + ret = -EINVAL; > + goto cti_not_disabled; > + } > + > /* check refcount - disable on 0 */ > if (atomic_dec_return(&drvdata->config.enable_req_count) > 0) > goto cti_not_disabled; > @@ -171,12 +178,12 @@ static int cti_disable_hw(struct cti_drvdata *drvdata) > coresight_disclaim_device_unlocked(csdev); > CS_LOCK(drvdata->base); > spin_unlock(&drvdata->spinlock); > - return 0; > + return ret; > > /* not disabled this call */ > cti_not_disabled: > spin_unlock(&drvdata->spinlock); > - return 0; > + return ret; > } > > void cti_write_single_reg(struct cti_drvdata *drvdata, int offset, u32 value)