PM: QoS: Fix misc device registration unwind

cpu_latency_qos_init() registers cpu_dma_latency first and, when
CONFIG_PM_QOS_CPU_SYSTEM_WAKEUP is enabled, registers cpu_wakeup_latency
afterwards. The second registration overwrites the first return value.

As a result, a failure to register cpu_dma_latency can be masked if the
second registration succeeds. Conversely, if cpu_dma_latency succeeds and
cpu_wakeup_latency fails, the function returns an error while leaving the
first misc device registered.

Return immediately on the first registration failure and deregister
cpu_dma_latency if the second registration fails.

Fixes: a4e6512a79d8 ("PM: QoS: Introduce a CPU system wakeup QoS limit")
Signed-off-by: Yuho Choi <dbgh9129@gmail.com>
Link: https://patch.msgid.link/20260608170748.82273-1-dbgh9129@gmail.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/kernel/power/qos.c b/kernel/power/qos.c
index 398b994b73aabf8352c48a83b454a56ae70e7b11..1944dbeb0d4c95d0edaaf85126e670a24fbafcbe 100644 (file)
--- a/kernel/power/qos.c
+++ b/kernel/power/qos.c
@@ -519,18 +519,23 @@ static int __init cpu_latency_qos_init(void)
        int ret;
 
        ret = misc_register(&cpu_latency_qos_miscdev);
-       if (ret < 0)
+       if (ret < 0) {
                pr_err("%s: %s setup failed\n", __func__,
                       cpu_latency_qos_miscdev.name);
+               return ret;
+       }
 
 #ifdef CONFIG_PM_QOS_CPU_SYSTEM_WAKEUP
        ret = misc_register(&cpu_wakeup_latency_qos_miscdev);
-       if (ret < 0)
+       if (ret < 0) {
                pr_err("%s: %s setup failed\n", __func__,
                       cpu_wakeup_latency_qos_miscdev.name);
+               misc_deregister(&cpu_latency_qos_miscdev);
+               return ret;
+       }
 #endif
 
-       return ret;
+       return 0;
 }
 late_initcall(cpu_latency_qos_init);
 #endif /* CONFIG_CPU_IDLE */