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[ Upstream commit79dde5f7dc] The cpu_latency_qos_add/remove/update_request interfaces lack internal synchronization by design, requiring the caller to ensure thread safety. The current implementation relies on the 'pm_qos_enabled' flag, which is insufficient to prevent concurrent access and cannot serve as a proper synchronization mechanism. This has led to data races and list corruption issues. A typical race condition call trace is: [Thread A] ufshcd_pm_qos_exit() --> cpu_latency_qos_remove_request() --> cpu_latency_qos_apply(); --> pm_qos_update_target() --> plist_del <--(1) delete plist node --> memset(req, 0, sizeof(*req)); --> hba->pm_qos_enabled = false; [Thread B] ufshcd_devfreq_target --> ufshcd_devfreq_scale --> ufshcd_scale_clks --> ufshcd_pm_qos_update <--(2) pm_qos_enabled is true --> cpu_latency_qos_update_request --> pm_qos_update_target --> plist_del <--(3) plist node use-after-free Introduces a dedicated mutex to serialize PM QoS operations, preventing data races and ensuring safe access to PM QoS resources, including sysfs interface reads. Fixes:2777e73fc1("scsi: ufs: core: Add CPU latency QoS support for UFS driver") Signed-off-by: Zhongqiu Han <zhongqiu.han@oss.qualcomm.com> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Huan Tang <tanghuan@vivo.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
1515 lines
49 KiB
1515 lines
49 KiB