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[68.147.8.254]) by smtp.gmail.com with ESMTPSA id n15sm2931735pgs.25.2020.07.29.11.01.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 29 Jul 2020 11:01:30 -0700 (PDT) Date: Wed, 29 Jul 2020 12:01:28 -0600 From: Mathieu Poirier To: Suzuki K Poulose Subject: Re: [RFC PATCH 01/14] coresight: etm4x: Skip save/restore before device registration Message-ID: <20200729180128.GA3073178@xps15> References: <20200722172040.1299289-1-suzuki.poulose@arm.com> <20200722172040.1299289-2-suzuki.poulose@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200722172040.1299289-2-suzuki.poulose@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200729_140134_052280_E7490105 X-CRM114-Status: GOOD ( 22.10 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: coresight@lists.linaro.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, mike.leach@linaro.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Suzuki, I have starte to review this - comments will be scattered over a few days. On Wed, Jul 22, 2020 at 06:20:27PM +0100, Suzuki K Poulose wrote: > Skip cpu save/restore before the coresight device is registered. > > Cc: Mathieu Poirier > Cc: Mike Leach > Signed-off-by: Suzuki K Poulose > --- > drivers/hwtracing/coresight/coresight-etm4x.c | 16 +++++++++++++++- > 1 file changed, 15 insertions(+), 1 deletion(-) > > diff --git a/drivers/hwtracing/coresight/coresight-etm4x.c b/drivers/hwtracing/coresight/coresight-etm4x.c > index 6d7d2169bfb2..cb83fb77ded6 100644 > --- a/drivers/hwtracing/coresight/coresight-etm4x.c > +++ b/drivers/hwtracing/coresight/coresight-etm4x.c > @@ -1135,7 +1135,13 @@ static int etm4_cpu_save(struct etmv4_drvdata *drvdata) > { > int i, ret = 0; > struct etmv4_save_state *state; > - struct device *etm_dev = &drvdata->csdev->dev; > + struct coresight_device *csdev = drvdata->csdev; > + struct device *etm_dev; > + > + if (WARN_ON(!csdev)) > + return -ENODEV; > + > + etm_dev = &csdev->dev; > > /* > * As recommended by 3.4.1 ("The procedure when powering down the PE") > @@ -1261,6 +1267,10 @@ static void etm4_cpu_restore(struct etmv4_drvdata *drvdata) > { > int i; > struct etmv4_save_state *state = drvdata->save_state; > + struct coresight_device *csdev = drvdata->csdev; > + > + if (WARN_ON(!csdev)) > + return; Restore and save operations are only called from etm4_cpu_pm_notify() where the check for a valid drvdata->csdev is already done. > > CS_UNLOCK(drvdata->base); > > @@ -1368,6 +1378,10 @@ static int etm4_cpu_pm_notify(struct notifier_block *nb, unsigned long cmd, > > drvdata = etmdrvdata[cpu]; > > + /* If we have not registered the device there is nothing to do */ > + if (!drvdata->csdev) > + return NOTIFY_OK; Can you describe the scenario you've seen this happening in? Probably best to add it to the changelog. > + > if (!drvdata->save_state) > return NOTIFY_OK; > > -- > 2.24.1 > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel