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Mon, 26 Oct 2026 02:21:09 -0700 (PDT) Received: from [192.168.226.26] ([178.235.128.140]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-c46bd34fbe6sm294029966b.10.2026.10.26.02.21.06 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 26 Oct 2026 02:21:08 -0700 (PDT) Message-ID: Date: Mon, 26 Oct 2026 10:21:06 +0100 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 01/14] drm/msm: fail the snapshot init when its worker cannot be created To: Dmitry Baryshkov , Rob Clark , Dmitry Baryshkov , Abhinav Kumar , Jessica Zhang , Sean Paul , Marijn Suijten , David Airlie , Simona Vetter Cc: linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org, freedreno@lists.freedesktop.org, linux-kernel@vger.kernel.org References: <20261024-msm-kms-destroy-fixes-v3-0-66a30120a5ea@oss.qualcomm.com> <20261024-msm-kms-destroy-fixes-v3-1-66a30120a5ea@oss.qualcomm.com> Content-Language: en-US From: Konrad Dybcio In-Reply-To: <20261024-msm-kms-destroy-fixes-v3-1-66a30120a5ea@oss.qualcomm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Proofpoint-ORIG-GUID: yb6IyZ_c6Ykq9f3yf2_8HPpUpr-5dhxw X-Authority-Analysis: v=2.4 cv=UfTE26SN c=1 sm=1 tr=0 ts=6adf1b86 cx=c_pps a=50t2pK5VMbmlHzFWWp8p/g==:117 a=PRfkaYvzSr8QmIIGAkY2Sg==:17 a=IkcTkHD0fZMA:10 a=660iZSQnnn4A:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=ZpdpYltYx_vBUK5n70dp:22 a=EUspDBNiAAAA:8 a=O4p-ns5tyOGKaCv9pfgA:9 a=QEXdDO2ut3YA:10 a=IoWCM6iH3mJn3m4BftBB:22 X-Proofpoint-GUID: yb6IyZ_c6Ykq9f3yf2_8HPpUpr-5dhxw X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMDI2MDAzNyBTYWx0ZWRfX7flIRFJ3WoRN BJc9CEyC67ff0xqDPAVIuRVX6sCQ0MCTwFZ8Ztw3dFVg8iaKrrcFh4JIztpY0ykxHFzPOMrZKz+ iGLOAZ5ZPZ3ZCieSRKW1ftF580iHfzgyLCuYAOym1oKplQOShvT1rcU/311GbUB8xmg56B31Wmj PxhotRG0qWVQAxwq8PDyRROFetdj6wMTPbJLyRt/IxoyfqLAkSd7SQZ1yyrfKViiiapL7Nv7gXE e8n7KK1sJN8WlXi0jpAoELKZA1mRpiF2cgKKKwUj20EOs6VMSJwWoNc0/kqdmq2I7AfI+PYcOvU 3z7G/cxZdce3qFlorCXqspv1bRYoYv25XKJJg+F39jKoeVUqYeLj71HNELMPtedDhhkZljeUugP MyPaISQzqUB/DnF1Sp1xl0St7sYTKVEXaQdxfG8ugYq00fUjzBxZWiNnKhtIYmZIh1VTLGCitVS 5l6HzmxU7E/QjVFYL6w== X-Proofpoint-Spam-Info: AW1haW4tMjYxMDI2MDAzNyBTYWx0ZWRfX7XgVCUnZ2JBc DplkmxZDrXHzTdcgOPicLqM2r6Wnp1brkAVJPrwCGyemrE27ZYfKAg72MM0Lm/soVRrPPv55kOu 5jXUV2ulfNHOvy7Q+eojfEBgTZVuLCY= X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.138,FMLib:17.12.100.49 definitions=2026-10-26_01,2026-10-21_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 lowpriorityscore=0 malwarescore=0 spamscore=0 bulkscore=0 suspectscore=0 impostorscore=0 phishscore=0 adultscore=0 clxscore=1015 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2610190000 definitions=main-2610260037 On 10/24/26 1:19 AM, Dmitry Baryshkov wrote: > msm_disp_snapshot_init() only logs a failure of kthread_run_worker() and > returns success, leaving the error pointer in kms->dump_worker. Both of > its users then dereference it: msm_disp_snapshot_state() queues the dump > work on it on the first display error, and msm_disp_snapshot_destroy() > only checks the pointer for NULL before passing it to > kthread_destroy_worker(). > > Clear the pointer and return the error instead, so that the KMS init > fails rather than leaving a snapshot facility which crashes when used. > > Fixes: 98659487b845 ("drm/msm: add support to take dpu snapshot") > Assisted-by: LLM > Signed-off-by: Dmitry Baryshkov > --- > drivers/gpu/drm/msm/disp/msm_disp_snapshot.c | 12 +++++++++++- > 1 file changed, 11 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/msm/disp/msm_disp_snapshot.c b/drivers/gpu/drm/msm/disp/msm_disp_snapshot.c > index d99771684728..d1b10656e41a 100644 > --- a/drivers/gpu/drm/msm/disp/msm_disp_snapshot.c > +++ b/drivers/gpu/drm/msm/disp/msm_disp_snapshot.c > @@ -98,6 +98,7 @@ int msm_disp_snapshot_init(struct drm_device *drm_dev) > { > struct msm_drm_private *priv; > struct msm_kms *kms; > + int ret; > > if (!drm_dev) { > DRM_ERROR("invalid params\n"); > @@ -110,12 +111,21 @@ int msm_disp_snapshot_init(struct drm_device *drm_dev) > mutex_init(&kms->dump_mutex); > > kms->dump_worker = kthread_run_worker(0, "%s", "disp_snapshot"); > - if (IS_ERR(kms->dump_worker)) > + if (IS_ERR(kms->dump_worker)) { > + ret = PTR_ERR(kms->dump_worker); > DRM_ERROR("failed to create disp state task\n"); > + goto err_destroy_mutex; > + } > > kthread_init_work(&kms->dump_work, _msm_disp_snapshot_work); > > return 0; > + > +err_destroy_mutex: > + kms->dump_worker = NULL; > + mutex_destroy(&kms->dump_mutex); LLM: The error path calls mutex_destroy(&kms->dump_mutex), but msm_disp_snapshot_destroy() runs later on the same failure path and destroys the mutex again. That's harmless in practice (mutex_destroy() on an unlocked mutex is benign, and the debug checks don't fire), but it's a redundant double destroy. A simpler version would drop the mutex handling from the error path and let the destroy function own it Konrad