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[103.229.16.4]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-29efb3657f0sm115430205ad.72.2025.12.15.02.09.48 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 15 Dec 2025 02:09:51 -0800 (PST) Message-ID: Date: Mon, 15 Dec 2025 18:09:45 +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 v2 RESEND] coresight: etm-perf: Fix reference count leak in etm_setup_aux To: Leo Yan , James Clark Cc: Ma Ke , coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, stable@vger.kernel.org, suzuki.poulose@arm.com, mike.leach@linaro.org, alexander.shishkin@linux.intel.com, mathieu.poirier@linaro.org References: <20251215022709.17220-1-make24@iscas.ac.cn> <20251215095103.GA681384@e132581.arm.com> Content-Language: en-US From: Jie Gan In-Reply-To: <20251215095103.GA681384@e132581.arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Authority-Analysis: v=2.4 cv=TtDrRTXh c=1 sm=1 tr=0 ts=693fde70 cx=c_pps a=MTSHoo12Qbhz2p7MsH1ifg==:117 a=nuhDOHQX5FNHPW3J6Bj6AA==:17 a=IkcTkHD0fZMA:10 a=wP3pNCr1ah4A:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=VwQbUJbxAAAA:8 a=quK4xr9WOROKk1m0v-0A:9 a=QEXdDO2ut3YA:10 a=GvdueXVYPmCkWapjIL-Q:22 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUxMjE1MDA4NiBTYWx0ZWRfXxIa6UjPvOj21 xPJ7I2PIEHHH77zA71YmHAwYHTDECIBFhJUZ5uf5KamPkZTA/JkhDf7ma7Ta7p8sLdP5RknG+cy ZLKe+GNSEjnNT5obaUei8BmnF48NwXTSaaOvflxMwRrBCBnrDcfJm+LgzEqfQlrrcSc/+Zot95m zX0A9luDLq9f0jF24YCiWNEYwQmIxT/rntj87MWG9Yu3vqMhVwKr0If9YONo7xjyxABV+FomsNa WhruGuuZydGAreUGIB7frQQdzvlYOikgJi02ovsLNYx7meavaQX/qgxDzP2kYXdibKkRvpZCSSa OVU3OTBoeK4cnREsMNxDRVAy+hr4JGUJMCc7rDxKw8vEcXxVn43/tZYyP0bWqVrpOfKFdCKKgob 60sHA2Td+3gdABy/gpGtnlxJvjSvHg== X-Proofpoint-GUID: -FogMPdjy5KeTnzWkVceTrB56TkFJf0B X-Proofpoint-ORIG-GUID: -FogMPdjy5KeTnzWkVceTrB56TkFJf0B X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.9,FMLib:17.12.100.49 definitions=2025-12-15_02,2025-12-15_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 clxscore=1015 priorityscore=1501 bulkscore=0 adultscore=0 impostorscore=0 malwarescore=0 phishscore=0 spamscore=0 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2510240001 definitions=main-2512150086 On 12/15/2025 5:51 PM, Leo Yan wrote: > On Mon, Dec 15, 2025 at 11:02:08AM +0200, James Clark wrote: >> >> >> On 15/12/2025 04:27, Ma Ke wrote: >>> In etm_setup_aux(), when a user sink is obtained via >>> coresight_get_sink_by_id(), it increments the reference count of the >>> sink device. However, if the sink is used in path building, the path >>> holds a reference, but the initial reference from >>> coresight_get_sink_by_id() is not released, causing a reference count >>> leak. We should release the initial reference after the path is built. >>> >>> Found by code review. >>> >>> Cc: stable@vger.kernel.org >>> Fixes: 0e6c20517596 ("coresight: etm-perf: Allow an event to use different sinks") >>> Signed-off-by: Ma Ke >>> --- >>> Changes in v2: >>> - modified the patch as suggestions. >> >> I think Leo's comment on the previous v2 is still unaddressed. But releasing >> it in coresight_get_sink_by_id() would make it consistent with >> coresight_find_csdev_by_fwnode() and prevent further mistakes. > > The point is the coresight core layer uses coresight_grab_device() to > increase the device's refcnt. This is why we don't need to grab a > device when setup AUX. That make sense. We dont need to hold the refcnt for a while and it should be released immediately after locating the required device. Thanks, Jie > >> It also leads me to see that users of coresight_find_device_by_fwnode() >> should also release it, but only one out of two appears to. > > Good finding! > > Thanks, > Leo >