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[103.229.16.4]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-cbdba63f806sm2111539a12.23.2026.07.30.03.08.04 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 30 Jul 2026 03:08:06 -0700 (PDT) Message-ID: <0637c5b9-2cf3-462c-9664-e809cb9bc177@oss.qualcomm.com> Date: Thu, 30 Jul 2026 18:07:53 +0800 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v16 3/7] qcom-tgu: Add signal priority support To: sashiko-reviews@lists.linux.dev Cc: devicetree@vger.kernel.org, robh@kernel.org, conor+dt@kernel.org References: <20260730080704.2903540-1-songwei.chai@oss.qualcomm.com> <20260730080704.2903540-4-songwei.chai@oss.qualcomm.com> <20260730081714.118D31F000E9@smtp.kernel.org> Content-Language: en-US From: "Songwei.Chai" In-Reply-To: <20260730081714.118D31F000E9@smtp.kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Proofpoint-Spam-Info: AW1haW4tMjYwNzMwMDA3NCBTYWx0ZWRfX8rqWh3ERw/ab r7t2EJDS8U13UTRVYmcblioKnCyckMcJauQK4gMlvX+T6Df0KR5RmbBiGZsdIaNnjTujiJ0p5lS tT/pkQtAqbnRgT3MJhhayC4EGUuNZXM= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzMwMDA3NCBTYWx0ZWRfX93/m1kOZ+eje 1FqVpT+xDrU6eCtFfDQNCLZ6fHZgsSoOi1MqpV4BMAwdle2AFeyOEg9suRuFQzD2dKgUuSIQ3vO 59jWNA74QCpJpXh4Cy+/1pIzMDdJmnhk/9iBYxqYelMQUfFfVRmh1o0f5r7GPQ8uk4iaUUwBDNa lKI3AUAjvRTH155BqaAiBiTU+kqlvFY4C9BWwvlbWDOcYXdITCQl119U4W1Zyt/zB58ESbKbnco aiA8s0x1BG16WsybUk2LgbBsj0fwqqdOk7/tjdfD4l8TE8+P7nawXDHNxbm9DFDFKOOg1VXnif5 6NL2jlews4T5llhnW9L7idE/jLT/HUKNYVKKI2RYrionCDOMzMO+i6WGZzN342FQ0ONNwYi360q YawhzqSFj6sdSw/Vj/lrkuhppqrNkJJ91gBirlbff/vJCzPnERoRMOOygRvR1KTzuMePkgi2aPd hdC0mKvMT3eDWJT8waQ== X-Proofpoint-ORIG-GUID: XSyx-hUs9_vlmxUmc3Ti_tttDUGi8bNG X-Proofpoint-GUID: XSyx-hUs9_vlmxUmc3Ti_tttDUGi8bNG X-Authority-Analysis: v=2.4 cv=Tb6mcxQh c=1 sm=1 tr=0 ts=6a6b2288 cx=c_pps a=mDZGXZTwRPZaeRUbqKGCBw==:117 a=nuhDOHQX5FNHPW3J6Bj6AA==:17 a=IkcTkHD0fZMA:10 a=RAioF0-LDSMA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=3WHJM1ZQz_JShphwDgj5:22 a=VwQbUJbxAAAA:8 a=EUspDBNiAAAA:8 a=Zh2D9iEZmoPOMH589UwA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 a=zc0IvFSfCIW2DFIPzwfm:22 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-07-30_03,2026-07-29_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 lowpriorityscore=0 priorityscore=1501 bulkscore=0 adultscore=0 clxscore=1015 suspectscore=0 impostorscore=0 spamscore=0 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607300074 On 7/30/2026 4:17 PM, sashiko-bot@kernel.org wrote: > Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider: > - [Medium] tgu_dataset_store allows writes while the device is enabled, causing silent software/hardware state desynchronization. > - [Medium] tgu_dataset_store silently truncates out-of-range priority values on 64-bit systems. > -- > > --- Patch [3]: [PATCH v16 3/7] qcom-tgu: Add signal priority support --- > commit 8afece15a767b432d65a919119df2e97aca2bed5 > Author: Songwei Chai > > qcom-tgu: Add signal priority support > > This commit adds signal priority configuration support to the Qualcomm TGU > driver. It introduces sysfs attributes to configure the priority of sensed > signals for each step, and stores these configurations in a dynamically > allocated table. > >> diff --git a/drivers/hwtracing/qcom/tgu.c b/drivers/hwtracing/qcom/tgu.c >> index 9c7dd4a09f027..0e88b437f191f 100644 >> --- a/drivers/hwtracing/qcom/tgu.c >> +++ b/drivers/hwtracing/qcom/tgu.c > [ ... ] > >> +static ssize_t tgu_dataset_store(struct device *dev, >> + struct device_attribute *attr, >> + const char *buf, size_t size) >> +{ >> + struct tgu_drvdata *tgu_drvdata = dev_get_drvdata(dev); >> + struct tgu_attribute *tgu_attr = >> + container_of(attr, struct tgu_attribute, attr); >> + unsigned long val; >> + int index; >> + int ret; >> + >> + ret = kstrtoul(buf, 0, &val); > [Severity: Medium] > Does this code silently truncate out-of-range priority values on 64-bit > systems? > > The function uses kstrtoul() to parse user input into an unsigned long. > Later, it directly assigns this value to > tgu_drvdata->value_table->priority[index], which is an array of unsigned int. > > On 64-bit systems, inputs exceeding UINT_MAX will be silently truncated > without returning an error like -ERANGE. Would kstrtouint() be more > appropriate here? |Clarification：| The target register is 32 bits wide (|REG_OFFSET = 0x4|). Therefore, any value larger than |UINT_MAX| cannot be represented by the hardware and is inherently meaningless. We can switch to |kstrtouint()| for stylistic consistency, but this is not a functional bug. > >> + if (ret) >> + return ret; >> + >> + guard(mutex)(&tgu_drvdata->lock); >> + index = calculate_array_location(tgu_drvdata, tgu_attr->step_index, >> + tgu_attr->operation_index, >> + tgu_attr->reg_num); >> + >> + tgu_drvdata->value_table->priority[index] = val; > [Severity: Medium] > Can this cause a silent desynchronization between software and hardware > state? > > If a user writes to this attribute while the TGU is actively tracing > (tgu_drvdata->enabled == true), the driver updates the software backing array > and returns success, but the hardware is not dynamically updated. Subsequent > reads will return the new value, giving the false impression that the hardware > configuration has changed. > > Should this check if the device is enabled and either return an error, or push > the update to the hardware registers? |Clarification：| The design is intentional. A complete TGU configuration spans multiple register groups (priority, condition_decode, condition_select, timer, counter). Writing hardware on every store would leave the engine in a transient, half-updated state between sysfs writes, which could feed a spurious match into CTI/interrupt consumers — exactly the hazard documented in tgu_write_all_hw_regs(). > >> + >> + return size; >> +}