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Wed, 29 Jan 2025 07:56:21 -0800 (PST) X-Google-Smtp-Source: AGHT+IF2B4B+YcV7qGpZDw1PDGvvKfkjXAwRuH8rb5D436/nFHKW3TBRf6iKCQFl+v3k5Lh4v3r6VA== X-Received: by 2002:a17:903:244b:b0:212:67a5:ab2d with SMTP id d9443c01a7336-21dd7df2d21mr59553325ad.44.1738166180910; Wed, 29 Jan 2025 07:56:20 -0800 (PST) Received: from hu-mojha-hyd.qualcomm.com ([202.46.23.25]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-21da414edb3sm100898975ad.202.2025.01.29.07.56.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 29 Jan 2025 07:56:20 -0800 (PST) From: Mukesh Ojha To: andersson@kernel.org, konradybcio@kernel.org Cc: linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, Mukesh Ojha , stable@vger.kernel.org, Saranya R Subject: [PATCH v2] soc: qcom: pdr: Fix the potential deadlock Date: Wed, 29 Jan 2025 21:25:44 +0530 Message-Id: <20250129155544.1864854-1-mukesh.ojha@oss.qualcomm.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-arm-msm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Proofpoint-GUID: NcE_PPUE37unZhIWwWBwLrvI2RQRT8jL X-Proofpoint-ORIG-GUID: NcE_PPUE37unZhIWwWBwLrvI2RQRT8jL X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1057,Hydra:6.0.680,FMLib:17.12.68.34 definitions=2025-01-29_03,2025-01-29_01,2024-11-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxscore=0 priorityscore=1501 malwarescore=0 phishscore=0 suspectscore=0 mlxlogscore=999 clxscore=1015 spamscore=0 lowpriorityscore=0 bulkscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2411120000 definitions=main-2501290128 When some client process A call pdr_add_lookup() to add the look up for the service and does schedule locator work, later a process B got a new server packet indicating locator is up and call pdr_locator_new_server() which eventually sets pdr->locator_init_complete to true which process A sees and takes list lock and queries domain list but it will timeout due to deadlock as the response will queued to the same qmi->wq and it is ordered workqueue and process B is not able to complete new server request work due to deadlock on list lock. Process A Process B process_scheduled_works() pdr_add_lookup() qmi_data_ready_work() process_scheduled_works() pdr_locator_new_server() pdr->locator_init_complete=true; pdr_locator_work() mutex_lock(&pdr->list_lock); pdr_locate_service() mutex_lock(&pdr->list_lock); pdr_get_domain_list() pr_err("PDR: %s get domain list txn wait failed: %d\n", req->service_name, ret); Fix it by removing the unnecessary list iteration as the list iteration is already being done inside locator work, so avoid it here and just call schedule_work() here. Fixes: fbe639b44a82 ("soc: qcom: Introduce Protection Domain Restart helpers") CC: stable@vger.kernel.org Signed-off-by: Saranya R Signed-off-by: Mukesh Ojha --- Changes in v2: - Added Fixes tag, drivers/soc/qcom/pdr_interface.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-) diff --git a/drivers/soc/qcom/pdr_interface.c b/drivers/soc/qcom/pdr_interface.c index 328b6153b2be..71be378d2e43 100644 --- a/drivers/soc/qcom/pdr_interface.c +++ b/drivers/soc/qcom/pdr_interface.c @@ -75,7 +75,6 @@ static int pdr_locator_new_server(struct qmi_handle *qmi, { struct pdr_handle *pdr = container_of(qmi, struct pdr_handle, locator_hdl); - struct pdr_service *pds; mutex_lock(&pdr->lock); /* Create a local client port for QMI communication */ @@ -87,12 +86,7 @@ static int pdr_locator_new_server(struct qmi_handle *qmi, mutex_unlock(&pdr->lock); /* Service pending lookup requests */ - mutex_lock(&pdr->list_lock); - list_for_each_entry(pds, &pdr->lookups, node) { - if (pds->need_locator_lookup) - schedule_work(&pdr->locator_work); - } - mutex_unlock(&pdr->list_lock); + schedule_work(&pdr->locator_work); return 0; }