4.14-stable review patch. If anyone has any objections, please let me know.
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From: Alexis Lothoré alexis.lothore@bootlin.com
[ 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@bootlin.com Link: https://lore.kernel.org/r/20231215-lockdep_warning-v1-1-8137b2510ed5@bootlin... Signed-off-by: Linus Walleij linus.walleij@linaro.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/pinctrl/pinctrl-at91-pio4.c | 8 ++++++++ 1 file changed, 8 insertions(+)
diff --git a/drivers/pinctrl/pinctrl-at91-pio4.c b/drivers/pinctrl/pinctrl-at91-pio4.c index 8f18a35b66b61..5ef7dd8c9ccf0 100644 --- a/drivers/pinctrl/pinctrl-at91-pio4.c +++ b/drivers/pinctrl/pinctrl-at91-pio4.c @@ -899,6 +899,13 @@ 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; @@ -1044,6 +1051,7 @@ 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);