drivers/perf/arm_cspmu/arm_cspmu.c:1075 arm_cspmu_find_cpu_container() warn: variable dereferenced before check 'cpu_dev' (see line 1073)

[Dan Carpenter]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   925cf0457d7e62ce08878ffb789189ac08ca8677
commit: e37dfd65731dc4f001fa7dfa7f705e6840017d5a perf: arm_cspmu: Add support for ARM CoreSight PMU driver
config: arm64-randconfig-m031-20230219 (https://download.01.org/0day-ci/archive/20230219/202302191227.kc0V8fM7-lkp@xxxxxxxxx/config)
compiler: aarch64-linux-gcc (GCC) 12.1.0

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@xxxxxxxxx>
| Reported-by: Dan Carpenter <error27@xxxxxxxxx>
| Link: https://lore.kernel.org/r/202302191227.kc0V8fM7-lkp@xxxxxxxxx/

smatch warnings:
drivers/perf/arm_cspmu/arm_cspmu.c:1075 arm_cspmu_find_cpu_container() warn: variable dereferenced before check 'cpu_dev' (see line 1073)

vim +/cpu_dev +1075 drivers/perf/arm_cspmu/arm_cspmu.c

e37dfd65731dc4 Besar Wicaksono 2022-11-11  1069  static inline int arm_cspmu_find_cpu_container(int cpu, u32 container_uid)
e37dfd65731dc4 Besar Wicaksono 2022-11-11  1070  {
e37dfd65731dc4 Besar Wicaksono 2022-11-11  1071  	u32 acpi_uid;
e37dfd65731dc4 Besar Wicaksono 2022-11-11  1072  	struct device *cpu_dev = get_cpu_device(cpu);
e37dfd65731dc4 Besar Wicaksono 2022-11-11 @1073  	struct acpi_device *acpi_dev = ACPI_COMPANION(cpu_dev);
                                                                                                      ^^^^^^^
Dereference

e37dfd65731dc4 Besar Wicaksono 2022-11-11  1074  
e37dfd65731dc4 Besar Wicaksono 2022-11-11 @1075  	if (!cpu_dev)
                                                             ^^^^^^^
Checked too late.

e37dfd65731dc4 Besar Wicaksono 2022-11-11  1076  		return -ENODEV;
e37dfd65731dc4 Besar Wicaksono 2022-11-11  1077  
e37dfd65731dc4 Besar Wicaksono 2022-11-11  1078  	while (acpi_dev) {
e37dfd65731dc4 Besar Wicaksono 2022-11-11  1079  		if (!strcmp(acpi_device_hid(acpi_dev),
e37dfd65731dc4 Besar Wicaksono 2022-11-11  1080  			    ACPI_PROCESSOR_CONTAINER_HID) &&
e37dfd65731dc4 Besar Wicaksono 2022-11-11  1081  		    !kstrtouint(acpi_device_uid(acpi_dev), 0, &acpi_uid) &&
e37dfd65731dc4 Besar Wicaksono 2022-11-11  1082  		    acpi_uid == container_uid)
e37dfd65731dc4 Besar Wicaksono 2022-11-11  1083  			return 0;
e37dfd65731dc4 Besar Wicaksono 2022-11-11  1084  
e37dfd65731dc4 Besar Wicaksono 2022-11-11  1085  		acpi_dev = acpi_dev_parent(acpi_dev);
e37dfd65731dc4 Besar Wicaksono 2022-11-11  1086  	}
e37dfd65731dc4 Besar Wicaksono 2022-11-11  1087  
e37dfd65731dc4 Besar Wicaksono 2022-11-11  1088  	return -ENODEV;
e37dfd65731dc4 Besar Wicaksono 2022-11-11  1089  }

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