79dde5f7dc
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:
|
||
|---|---|---|
| .. | ||
| acpi | ||
| asm-generic | ||
| clocksource | ||
| crypto | ||
| cxl | ||
| drm | ||
| dt-bindings | ||
| hyperv | ||
| keys | ||
| kunit | ||
| kvm | ||
| linux | ||
| math-emu | ||
| media | ||
| memory | ||
| misc | ||
| net | ||
| pcmcia | ||
| ras | ||
| rdma | ||
| rv | ||
| scsi | ||
| soc | ||
| sound | ||
| target | ||
| trace | ||
| uapi | ||
| ufs | ||
| vdso | ||
| video | ||
| xen | ||
| Kbuild | ||