linux-kernel - [PATCH RESEND] thermal/drivers/qcom/lmh: remove false lockdep backtrace

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Message-Id: <20241101-lmh-lockdep-v1-1-96fd53cc241c@linaro.org>
Date: Fri, 01 Nov 2024 03:04:42 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Amit Kucheria <amitk@...nel.org>, 
 Thara Gopinath <thara.gopinath@...il.com>, 
 "Rafael J. Wysocki" <rafael@...nel.org>, 
 Daniel Lezcano <daniel.lezcano@...aro.org>, Zhang Rui <rui.zhang@...el.com>, 
 Lukasz Luba <lukasz.luba@....com>
Cc: Thara Gopinath <thara.gopinath@...aro.org>, linux-pm@...r.kernel.org, 
 linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org, 
 stable@...r.kernel.org
Subject: [PATCH RESEND] thermal/drivers/qcom/lmh: remove false lockdep
 backtrace

Annotate LMH IRQs with lockdep classes so that the lockdep doesn't
report possible recursive locking issue between LMH and GIC interrupts.

For the reference:

       CPU0
       ----
  lock(&irq_desc_lock_class);
  lock(&irq_desc_lock_class);

 *** DEADLOCK ***

Call trace:
 dump_backtrace+0x98/0xf0
 show_stack+0x18/0x24
 dump_stack_lvl+0x90/0xd0
 dump_stack+0x18/0x24
 print_deadlock_bug+0x258/0x348
 __lock_acquire+0x1078/0x1f44
 lock_acquire+0x1fc/0x32c
 _raw_spin_lock_irqsave+0x60/0x88
 __irq_get_desc_lock+0x58/0x98
 enable_irq+0x38/0xa0
 lmh_enable_interrupt+0x2c/0x38
 irq_enable+0x40/0x8c
 __irq_startup+0x78/0xa4
 irq_startup+0x78/0x168
 __enable_irq+0x70/0x7c
 enable_irq+0x4c/0xa0
 qcom_cpufreq_ready+0x20/0x2c
 cpufreq_online+0x2a8/0x988
 cpufreq_add_dev+0x80/0x98
 subsys_interface_register+0x104/0x134
 cpufreq_register_driver+0x150/0x234
 qcom_cpufreq_hw_driver_probe+0x2a8/0x388
 platform_probe+0x68/0xc0
 really_probe+0xbc/0x298
 __driver_probe_device+0x78/0x12c
 driver_probe_device+0x3c/0x160
 __device_attach_driver+0xb8/0x138
 bus_for_each_drv+0x84/0xe0
 __device_attach+0x9c/0x188
 device_initial_probe+0x14/0x20
 bus_probe_device+0xac/0xb0
 deferred_probe_work_func+0x8c/0xc8
 process_one_work+0x20c/0x62c
 worker_thread+0x1bc/0x36c
 kthread+0x120/0x124
 ret_from_fork+0x10/0x20

Fixes: 53bca371cdf7 ("thermal/drivers/qcom: Add support for LMh driver")
Cc: stable@...r.kernel.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
---
 drivers/thermal/qcom/lmh.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/thermal/qcom/lmh.c b/drivers/thermal/qcom/lmh.c
index 5225b3621a56c4a11f0ae56af1060d6d1460ef02..d2d49264cf83a4c4646202044700a7a8bf3c0b95 100644
--- a/drivers/thermal/qcom/lmh.c
+++ b/drivers/thermal/qcom/lmh.c
@@ -73,7 +73,14 @@ static struct irq_chip lmh_irq_chip = {
 static int lmh_irq_map(struct irq_domain *d, unsigned int irq, irq_hw_number_t hw)
 {
 	struct lmh_hw_data *lmh_data = d->host_data;
+	static struct lock_class_key lmh_lock_key;
+	static struct lock_class_key lmh_request_key;
 
+	/*
+	 * This lock class tells lockdep that GPIO irqs are in a different
+	 * category than their parents, so it won't report false recursion.
+	 */
+	irq_set_lockdep_class(irq, &lmh_lock_key, &lmh_request_key);
 	irq_set_chip_and_handler(irq, &lmh_irq_chip, handle_simple_irq);
 	irq_set_chip_data(irq, lmh_data);
 

---
base-commit: 797012914d2d031430268fe512af0ccd7d8e46ef
change-id: 20240721-lmh-lockdep-88de09e77089

Best regards,
-- 
Dmitry Baryshkov <dmitry.baryshkov@...aro.org>