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.

Fixes: 60949b7b8054 ("ACPI: CPPC: Fix MASK_VAL() usage")
Signed-off-by: Pierre Gondois <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
[ rjw: Changelog edits ]
Signed-off-by: Rafael J. Wysocki <[e-mail]>

drivers/acpi/cppc_acpi.c

···
 
 	/* Store CPU Logical ID */
 	cpc_ptr->cpu_id = pr->id;
-	spin_lock_init(&cpc_ptr->rmw_lock);
+	raw_spin_lock_init(&cpc_ptr->rmw_lock);
 
 	/* Parse PSD data for this CPU */
 	ret = acpi_get_psd(cpc_ptr, handle);
···
 	int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu);
 	struct cpc_reg *reg = &reg_res->cpc_entry.reg;
 	struct cpc_desc *cpc_desc;
+	unsigned long flags;
 
 	size = GET_BIT_WIDTH(reg);
 
···
 			return -ENODEV;
 		}
 
-		spin_lock(&cpc_desc->rmw_lock);
+		raw_spin_lock_irqsave(&cpc_desc->rmw_lock, flags);
 		switch (size) {
 		case 8:
 			prev_val = readb_relaxed(vaddr);
···
 			prev_val = readq_relaxed(vaddr);
 			break;
 		default:
-			spin_unlock(&cpc_desc->rmw_lock);
+			raw_spin_unlock_irqrestore(&cpc_desc->rmw_lock, flags);
 			return -EFAULT;
 		}
 		val = MASK_VAL_WRITE(reg, prev_val, val);
···
 	}
 
 	if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY)
-		spin_unlock(&cpc_desc->rmw_lock);
+		raw_spin_unlock_irqrestore(&cpc_desc->rmw_lock, flags);
 
 	return ret_val;
 }

include/acpi/cppc_acpi.h

···
 	int write_cmd_status;
 	int write_cmd_id;
 	/* Lock used for RMW operations in cpc_write() */
-	spinlock_t rmw_lock;
+	raw_spinlock_t rmw_lock;
 	struct cpc_register_resource cpc_regs[MAX_CPC_REG_ENT];
 	struct acpi_psd_package domain_info;
 	struct kobject kobj;