linux-kernel - [PATCH] ACPI: CPPC: Make rmw_lock a raw_spin

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Message-Id: <20241028105200.1205509-1-pierre.gondois@arm.com>
Date: Mon, 28 Oct 2024 11:51:49 +0100
From: Pierre Gondois <pierre.gondois@....com>
To: linux-kernel@...r.kernel.org
Cc: Dietmar Eggemann <dietmar.eggemann@....com>,
	Pierre Gondois <pierre.gondois@....com>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will@...nel.org>,
	Paul Walmsley <paul.walmsley@...ive.com>,
	Palmer Dabbelt <palmer@...belt.com>,
	Albert Ou <aou@...s.berkeley.edu>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Len Brown <lenb@...nel.org>,
	Sudeep Holla <sudeep.holla@....com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	Clark Williams <clrkwllms@...nel.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Jeremy Linton <jeremy.linton@....com>,
	Yunhui Cui <cuiyunhui@...edance.com>,
	Conor Dooley <conor.dooley@...rochip.com>,
	Steffen Persvold <spersvold@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	"Borislav Petkov (AMD)" <bp@...en8.de>,
	Reinette Chatre <reinette.chatre@...el.com>,
	Tony Luck <tony.luck@...el.com>,
	Yury Norov <yury.norov@...il.com>,
	Clément Léger <cleger@...osinc.com>,
	linux-arm-kernel@...ts.infradead.org,
	linux-riscv@...ts.infradead.org,
	linux-acpi@...r.kernel.org,
	linux-rt-devel@...ts.linux.dev
Subject: [PATCH] ACPI: CPPC: Make rmw_lock a raw_spin_lock

The following BUG was triggered. 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.

Also save irq state.

=============================
[ 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

Fixes: 60949b7b8054 ("ACPI: CPPC: Fix MASK_VAL() usage")
Signed-off-by: Pierre Gondois <pierre.gondois@....com>
---
 drivers/acpi/cppc_acpi.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
index 1a40f0514eaa..e7e4bf932e28 100644
--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -1127,7 +1127,7 @@ static int cpc_write(int cpu, struct cpc_register_resource *reg_res, u64 val)
 			return -ENODEV;
 		}
 
-		raw_spin_lock_irqsave(&cpc_desc->rmw_lock, flags);
+		raw_spin_lock(&cpc_desc->rmw_lock);
 		switch (size) {
 		case 8:
 			prev_val = readb_relaxed(vaddr);
@@ -1142,7 +1142,7 @@ static int cpc_write(int cpu, struct cpc_register_resource *reg_res, u64 val)
 			prev_val = readq_relaxed(vaddr);
 			break;
 		default:
-			raw_spin_unlock_irqrestore(&cpc_desc->rmw_lock, flags);
+			raw_spin_unlock(&cpc_desc->rmw_lock);
 			return -EFAULT;
 		}
 		val = MASK_VAL_WRITE(reg, prev_val, val);
@@ -1175,7 +1175,7 @@ static int cpc_write(int cpu, struct cpc_register_resource *reg_res, u64 val)
 	}
 
 	if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY)
-		raw_spin_unlock_irqrestore(&cpc_desc->rmw_lock, flags);
+		raw_spin_unlock(&cpc_desc->rmw_lock);
 
 	return ret_val;
 }
-- 
2.25.1