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[103.229.16.4]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-c7957eeb35csm1569622a12.12.2026.04.15.05.00.01 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 15 Apr 2026 05:00:04 -0700 (PDT) Message-ID: Date: Wed, 15 Apr 2026 19:59:59 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 5/9] coresight: etm4x: remove redundant call etm4_enable_hw() with hotplug To: Yeoreum Yun , coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Cc: suzuki.poulose@arm.com, mike.leach@arm.com, james.clark@linaro.org, alexander.shishkin@linux.intel.com, leo.yan@arm.com References: <20260413142003.3549310-1-yeoreum.yun@arm.com> <20260413142003.3549310-6-yeoreum.yun@arm.com> Content-Language: en-US From: Jie Gan In-Reply-To: <20260413142003.3549310-6-yeoreum.yun@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Authority-Analysis: v=2.4 cv=A7Zc+aWG c=1 sm=1 tr=0 ts=69df7dc6 cx=c_pps a=0uOsjrqzRL749jD1oC5vDA==:117 a=nuhDOHQX5FNHPW3J6Bj6AA==:17 a=IkcTkHD0fZMA:10 a=A5OVakUREuEA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=DJpcGTmdVt4CTyJn9g5Z:22 a=7CQSdrXTAAAA:8 a=EUspDBNiAAAA:8 a=vHEE0SP3H1NCSIy07DoA:9 a=QEXdDO2ut3YA:10 a=mQ_c8vxmzFEMiUWkPHU9:22 a=a-qgeE7W1pNrGK8U0ZQC:22 X-Proofpoint-ORIG-GUID: luOEohng0A33fxPg6om7cMA5H6jxiga5 X-Proofpoint-GUID: luOEohng0A33fxPg6om7cMA5H6jxiga5 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNDE1MDExMCBTYWx0ZWRfX4ik2rQsdkRxI B1sw5zNfeSEb1b8sQBoZecUszzetr6l4DSlyTZVA82Rpi+k15a3Ybk+lm+dThZlI6QrAB7bN6vl mnGIrQ4vE8XhAPbiU7ss2OO32L/hG6iJF12rtx1S1F83F75NR6Kl45Ju0Bd1uy/5h+qMsiLHyGq /oARdz62nN82GNVz2BL9zUrKHZSwgajEKX1gwfcmRoNKdgPEriwyWfPfYyTC90uT83L2N7juayh oKNVTxt4L82mIAflyri9aGG27hP8TQxLoORl6NyMLhoB2vwYfeviRb2pU3wOPP+1v0sw4/hCruT WTySs6ENod9ktHQ60tG2vAie2J62dfzwE4Qi1eYjUsL2HmL+3R+Zc7ee6VxVIks43Ker+vHUZHK uP5PoCKm92QVPvOQMJAZJC5wLz8ZufMH66Vj/nL3zeAFzvE99CcSA2rOlzsMBkxkCK3Fx0XLVXe Cz2Hh97m1h8BXdIXrlw== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-04-14_04,2026-04-13_04,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 spamscore=0 adultscore=0 bulkscore=0 priorityscore=1501 phishscore=0 impostorscore=0 lowpriorityscore=0 suspectscore=0 clxscore=1015 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2604070000 definitions=main-2604150110 On 4/13/2026 10:19 PM, Yeoreum Yun wrote: > The cpu_online_mask is set at the CPUHP_BRINGUP_CPU step. > In other words, if etm4_enable_sysfs() is called between > CPUHP_BRINGUP_CPU and CPUHP_AP_ARM_CORESIGHT_STARTING, > etm4_enable_hw() may be invoked in etm4_enable_sysfs_smp_call() > and then executed again in etm4_starting_cpu(). > > To remove this redundant call, take the hotplug lock before executing > etm4_enable_sysfs_smp_call(). > > Signed-off-by: Yeoreum Yun > --- > drivers/hwtracing/coresight/coresight-etm4x-core.c | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c > index 01099689525b..facd5a306228 100644 > --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c > +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c > @@ -959,8 +959,20 @@ static int etm4_enable_sysfs(struct coresight_device *csdev, struct coresight_pa > arg.config = drvdata->config; > raw_spin_unlock(&drvdata->spinlock); > > + /* > + * Take the hotplug lock to prevent redundant calls to etm4_enable_hw(). > + * > + * The cpu_online_mask is set at the CPUHP_BRINGUP_CPU step. > + * In other words, if etm4_enable_sysfs() is called between > + * CPUHP_BRINGUP_CPU and CPUHP_AP_ARM_CORESIGHT_STARTING, > + * etm4_enable_hw() may be invoked in etm4_enable_sysfs_smp_call() > + * and then executed again in etm4_starting_cpu(). > + */ > + cpus_read_lock(); > ret = smp_call_function_single(drvdata->cpu, > etm4_enable_sysfs_smp_call, &arg, 1); > + cpus_read_unlock(); > + > if (!ret) > ret = arg.rc; > if (!ret) Reviewed-by: Jie Gan