This is a note to let you know that I've just added the patch titled
pinctrl: at91-pio4: use dedicated lock class for IRQ
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
pinctrl-at91-pio4-use-dedicated-lock-class-for-irq.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 9c7992373278333cebac5423a80ddd7a9a2ae428
Author: Alexis Lothoré <alexis.lothore@xxxxxxxxxxx>
Date: Fri Dec 15 22:34:24 2023 +0100
pinctrl: at91-pio4: use dedicated lock class for IRQ
[ Upstream commit 14694179e561b5f2f7e56a0f590e2cb49a9cc7ab ]
Trying to suspend to RAM on SAMA5D27 EVK leads to the following lockdep
warning:
============================================
WARNING: possible recursive locking detected
6.7.0-rc5-wt+ #532 Not tainted
--------------------------------------------
sh/92 is trying to acquire lock:
c3cf306c (&irq_desc_lock_class){-.-.}-{2:2}, at: __irq_get_desc_lock+0xe8/0x100
but task is already holding lock:
c3d7c46c (&irq_desc_lock_class){-.-.}-{2:2}, at: __irq_get_desc_lock+0xe8/0x100
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(&irq_desc_lock_class);
lock(&irq_desc_lock_class);
*** DEADLOCK ***
May be due to missing lock nesting notation
6 locks held by sh/92:
#0: c3aa0258 (sb_writers#6){.+.+}-{0:0}, at: ksys_write+0xd8/0x178
#1: c4c2df44 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_write_iter+0x138/0x284
#2: c32684a0 (kn->active){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x148/0x284
#3: c232b6d4 (system_transition_mutex){+.+.}-{3:3}, at: pm_suspend+0x13c/0x4e8
#4: c387b088 (&dev->mutex){....}-{3:3}, at: __device_suspend+0x1e8/0x91c
#5: c3d7c46c (&irq_desc_lock_class){-.-.}-{2:2}, at: __irq_get_desc_lock+0xe8/0x100
stack backtrace:
CPU: 0 PID: 92 Comm: sh Not tainted 6.7.0-rc5-wt+ #532
Hardware name: Atmel SAMA5
unwind_backtrace from show_stack+0x18/0x1c
show_stack from dump_stack_lvl+0x34/0x48
dump_stack_lvl from __lock_acquire+0x19ec/0x3a0c
__lock_acquire from lock_acquire.part.0+0x124/0x2d0
lock_acquire.part.0 from _raw_spin_lock_irqsave+0x5c/0x78
_raw_spin_lock_irqsave from __irq_get_desc_lock+0xe8/0x100
__irq_get_desc_lock from irq_set_irq_wake+0xa8/0x204
irq_set_irq_wake from atmel_gpio_irq_set_wake+0x58/0xb4
atmel_gpio_irq_set_wake from irq_set_irq_wake+0x100/0x204
irq_set_irq_wake from gpio_keys_suspend+0xec/0x2b8
gpio_keys_suspend from dpm_run_callback+0xe4/0x248
dpm_run_callback from __device_suspend+0x234/0x91c
__device_suspend from dpm_suspend+0x224/0x43c
dpm_suspend from dpm_suspend_start+0x9c/0xa8
dpm_suspend_start from suspend_devices_and_enter+0x1e0/0xa84
suspend_devices_and_enter from pm_suspend+0x460/0x4e8
pm_suspend from state_store+0x78/0xe4
state_store from kernfs_fop_write_iter+0x1a0/0x284
kernfs_fop_write_iter from vfs_write+0x38c/0x6f4
vfs_write from ksys_write+0xd8/0x178
ksys_write from ret_fast_syscall+0x0/0x1c
Exception stack(0xc52b3fa8 to 0xc52b3ff0)
3fa0: 00000004 005a0ae8 00000001 005a0ae8 00000004 00000001
3fc0: 00000004 005a0ae8 00000001 00000004 00000004 b6c616c0 00000020 0059d190
3fe0: 00000004 b6c61678 aec5a041 aebf1a26
This warning is raised because pinctrl-at91-pio4 uses chained IRQ. Whenever
a wake up source configures an IRQ through irq_set_irq_wake, it will
lock the corresponding IRQ desc, and then call irq_set_irq_wake on "parent"
IRQ which will do the same on its own IRQ desc, but since those two locks
share the same class, lockdep reports this as an issue.
Fix lockdep false positive by setting a different class for parent and
children IRQ
Fixes: 776180848b57 ("pinctrl: introduce driver for Atmel PIO4 controller")
Signed-off-by: Alexis Lothoré <alexis.lothore@xxxxxxxxxxx>
Link: https://lore.kernel.org/r/20231215-lockdep_warning-v1-1-8137b2510ed5@xxxxxxxxxxx
Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/pinctrl/pinctrl-at91-pio4.c b/drivers/pinctrl/pinctrl-at91-pio4.c
index 383309e533c3d..a27c01fcbb47e 100644
--- a/drivers/pinctrl/pinctrl-at91-pio4.c
+++ b/drivers/pinctrl/pinctrl-at91-pio4.c
@@ -1068,6 +1068,13 @@ static const struct of_device_id atmel_pctrl_of_match[] = {
}
};
+/*
+ * This lock class allows to tell lockdep that parent IRQ and children IRQ do
+ * not share the same class so it does not raise false positive
+ */
+static struct lock_class_key atmel_lock_key;
+static struct lock_class_key atmel_request_key;
+
static int atmel_pinctrl_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
@@ -1214,6 +1221,7 @@ static int atmel_pinctrl_probe(struct platform_device *pdev)
irq_set_chip_and_handler(irq, &atmel_gpio_irq_chip,
handle_simple_irq);
irq_set_chip_data(irq, atmel_pioctrl);
+ irq_set_lockdep_class(irq, &atmel_lock_key, &atmel_request_key);
dev_dbg(dev,
"atmel gpio irq domain: hwirq: %d, linux irq: %d\n",
i, irq);
