archive mirror
 help / color / mirror / Atom feed
From: Samuel Holland <>
To: Linus Walleij <>,
	Maxime Ripard <>, Chen-Yu Tsai <>,
	Jernej Skrabec <>,,
	Samuel Holland <>,
	Guenter Roeck <>
Subject: [PATCH] pinctrl: sunxi: Use unique lockdep classes for IRQs
Date: Tue, 15 Feb 2022 22:00:36 -0600	[thread overview]
Message-ID: <> (raw)

This driver, like several others, uses a chained IRQ for each GPIO bank,
and forwards .irq_set_wake to the GPIO bank's upstream IRQ. As a result,
a call to irq_set_irq_wake() needs to lock both the upstream and
downstream irq_desc's. Lockdep considers this to be a possible deadlock
when the irq_desc's share lockdep classes, which they do by default:

 WARNING: possible recursive locking detected
 5.17.0-rc3-00394-gc849047c2473 #1 Not tainted
 init/307 is trying to acquire lock:
 c2dfe27c (&irq_desc_lock_class){-.-.}-{2:2}, at: __irq_get_desc_lock+0x58/0xa0

 but task is already holding lock:
 c3c0ac7c (&irq_desc_lock_class){-.-.}-{2:2}, at: __irq_get_desc_lock+0x58/0xa0

 other info that might help us debug this:
  Possible unsafe locking scenario:


  *** DEADLOCK ***

  May be due to missing lock nesting notation

 4 locks held by init/307:
  #0: c1f29f18 (system_transition_mutex){+.+.}-{3:3}, at: __do_sys_reboot+0x90/0x23c
  #1: c20f7760 (&dev->mutex){....}-{3:3}, at: device_shutdown+0xf4/0x224
  #2: c2e804d8 (&dev->mutex){....}-{3:3}, at: device_shutdown+0x104/0x224
  #3: c3c0ac7c (&irq_desc_lock_class){-.-.}-{2:2}, at: __irq_get_desc_lock+0x58/0xa0

 stack backtrace:
 CPU: 0 PID: 307 Comm: init Not tainted 5.17.0-rc3-00394-gc849047c2473 #1
 Hardware name: Allwinner sun8i Family
  unwind_backtrace from show_stack+0x10/0x14
  show_stack from dump_stack_lvl+0x68/0x90
  dump_stack_lvl from __lock_acquire+0x1680/0x31a0
  __lock_acquire from lock_acquire+0x148/0x3dc
  lock_acquire from _raw_spin_lock_irqsave+0x50/0x6c
  _raw_spin_lock_irqsave from __irq_get_desc_lock+0x58/0xa0
  __irq_get_desc_lock from irq_set_irq_wake+0x2c/0x19c
  irq_set_irq_wake from irq_set_irq_wake+0x13c/0x19c
    [tail call from sunxi_pinctrl_irq_set_wake]
  irq_set_irq_wake from gpio_keys_suspend+0x80/0x1a4
  gpio_keys_suspend from gpio_keys_shutdown+0x10/0x2c
  gpio_keys_shutdown from device_shutdown+0x180/0x224
  device_shutdown from __do_sys_reboot+0x134/0x23c
  __do_sys_reboot from ret_fast_syscall+0x0/0x1c

However, this can never deadlock because the upstream and downstream
IRQs are never the same (nor do they even involve the same irqchip).

Silence this erroneous lockdep splat by applying what appears to be the
usual fix of moving the GPIO IRQs to separate lockdep classes.

Fixes: a59c99d9eaf9 ("pinctrl: sunxi: Forward calls to irq_set_irq_wake")
Reported-by: Guenter Roeck <>
Signed-off-by: Samuel Holland <>

 drivers/pinctrl/sunxi/pinctrl-sunxi.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/pinctrl/sunxi/pinctrl-sunxi.c b/drivers/pinctrl/sunxi/pinctrl-sunxi.c
index 80d6750c74a6..9e6ed1175db3 100644
--- a/drivers/pinctrl/sunxi/pinctrl-sunxi.c
+++ b/drivers/pinctrl/sunxi/pinctrl-sunxi.c
@@ -36,6 +36,13 @@
 #include "../core.h"
 #include "pinctrl-sunxi.h"
+ * These lock classes tell lockdep that GPIO IRQs are in a different
+ * category than their parents, so it won't report false recursion.
+ */
+static struct lock_class_key sunxi_pinctrl_irq_lock_class;
+static struct lock_class_key sunxi_pinctrl_irq_request_class;
 static struct irq_chip sunxi_pinctrl_edge_irq_chip;
 static struct irq_chip sunxi_pinctrl_level_irq_chip;
@@ -1555,6 +1562,8 @@ int sunxi_pinctrl_init_with_variant(struct platform_device *pdev,
 	for (i = 0; i < (pctl->desc->irq_banks * IRQ_PER_BANK); i++) {
 		int irqno = irq_create_mapping(pctl->domain, i);
+		irq_set_lockdep_class(irqno, &sunxi_pinctrl_irq_lock_class,
+				      &sunxi_pinctrl_irq_request_class);
 		irq_set_chip_and_handler(irqno, &sunxi_pinctrl_edge_irq_chip,
 		irq_set_chip_data(irqno, pctl);

             reply	other threads:[~2022-02-16  4:00 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-16  4:00 Samuel Holland [this message]
2022-02-16  4:26 ` [PATCH] pinctrl: sunxi: Use unique lockdep classes for IRQs Guenter Roeck
2022-02-16 16:23 ` Jernej Škrabec
2022-02-19  1:13 ` Linus Walleij

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \ \ \ \ \ \ \ \ \ \ \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).