thermal: intel_powerclamp: Use get_cpu() instead of smp_processor_id() to avoid crash

In the Linux kernel, the following vulnerability has been resolved:

thermal: intel_powerclamp: Use get_cpu() instead of smp_processor_id() to avoid crash

When CPU 0 is offline and intel_powerclamp is used to inject

idle, it generates kernel BUG:

BUG: using smp_processor_id() in preemptible [00000000] code: bash/15687

caller is debug_smp_processor_id+0x17/0x20

CPU: 4 PID: 15687 Comm: bash Not tainted 5.19.0-rc7+ #57

Call Trace:

<TASK>

dump_stack_lvl+0x49/0x63

dump_stack+0x10/0x16

check_preemption_disabled+0xdd/0xe0

debug_smp_processor_id+0x17/0x20

powerclamp_set_cur_state+0x7f/0xf9 [intel_powerclamp]

...

...

Here CPU 0 is the control CPU by default and changed to the current CPU,

if CPU 0 offlined. This check has to be performed under cpus_read_lock(),

hence the above warning.

Use get_cpu() instead of smp_processor_id() to avoid this BUG.

[ rjw: Subject edits ]