ACPI: CPPC: Make rmw_lock a raw_spin_lock

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

ACPI: CPPC: Make rmw_lock a raw_spin_lock

The following BUG was triggered:

=============================

[ BUG: Invalid wait context ]

6.12.0-rc2-XXX #406 Not tainted

-----------------------------

kworker/1:1/62 is trying to lock:

ffffff8801593030 (&cpc_ptr->rmw_lock){+.+.}-{3:3}, at: cpc_write+0xcc/0x370

other info that might help us debug this:

context-{5:5}

2 locks held by kworker/1:1/62:

#0: ffffff897ef5ec98 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2c/0x50

#1: ffffff880154e238 (&sg_policy->update_lock){....}-{2:2}, at: sugov_update_shared+0x3c/0x280

stack backtrace:

CPU: 1 UID: 0 PID: 62 Comm: kworker/1:1 Not tainted 6.12.0-rc2-g9654bd3e8806 #406

Workqueue: 0x0 (events)

Call trace:

dump_backtrace+0xa4/0x130

show_stack+0x20/0x38

dump_stack_lvl+0x90/0xd0

dump_stack+0x18/0x28

__lock_acquire+0x480/0x1ad8

lock_acquire+0x114/0x310

_raw_spin_lock+0x50/0x70

cpc_write+0xcc/0x370

cppc_set_perf+0xa0/0x3a8

cppc_cpufreq_fast_switch+0x40/0xc0

cpufreq_driver_fast_switch+0x4c/0x218

sugov_update_shared+0x234/0x280

update_load_avg+0x6ec/0x7b8

dequeue_entities+0x108/0x830

dequeue_task_fair+0x58/0x408

__schedule+0x4f0/0x1070

schedule+0x54/0x130

worker_thread+0xc0/0x2e8

kthread+0x130/0x148

ret_from_fork+0x10/0x20

sugov_update_shared() locks a raw_spinlock while cpc_write() locks a

spinlock.

To have a correct wait-type order, update rmw_lock to a raw spinlock and

ensure that interrupts will be disabled on the CPU holding it.

[ rjw: Changelog edits ]