From: Andrew Lunn andrew@lunn.ch
[ Upstream commit f6d9758b12660484b6639364cc406da92a918c96 ]
The following false positive lockdep splat has been observed.
====================================================== WARNING: possible circular locking dependency detected 4.20.0+ #302 Not tainted ------------------------------------------------------ systemd-udevd/160 is trying to acquire lock: edea6080 (&chip->reg_lock){+.+.}, at: __setup_irq+0x640/0x704
but task is already holding lock: edff0340 (&desc->request_mutex){+.+.}, at: __setup_irq+0xa0/0x704
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (&desc->request_mutex){+.+.}: mutex_lock_nested+0x1c/0x24 __setup_irq+0xa0/0x704 request_threaded_irq+0xd0/0x150 mv88e6xxx_probe+0x41c/0x694 [mv88e6xxx] mdio_probe+0x2c/0x54 really_probe+0x200/0x2c4 driver_probe_device+0x5c/0x174 __driver_attach+0xd8/0xdc bus_for_each_dev+0x58/0x7c bus_add_driver+0xe4/0x1f0 driver_register+0x7c/0x110 mdio_driver_register+0x24/0x58 do_one_initcall+0x74/0x2e8 do_init_module+0x60/0x1d0 load_module+0x1968/0x1ff4 sys_finit_module+0x8c/0x98 ret_fast_syscall+0x0/0x28 0xbedf2ae8
-> #0 (&chip->reg_lock){+.+.}: __mutex_lock+0x50/0x8b8 mutex_lock_nested+0x1c/0x24 __setup_irq+0x640/0x704 request_threaded_irq+0xd0/0x150 mv88e6xxx_g2_irq_setup+0xcc/0x1b4 [mv88e6xxx] mv88e6xxx_probe+0x44c/0x694 [mv88e6xxx] mdio_probe+0x2c/0x54 really_probe+0x200/0x2c4 driver_probe_device+0x5c/0x174 __driver_attach+0xd8/0xdc bus_for_each_dev+0x58/0x7c bus_add_driver+0xe4/0x1f0 driver_register+0x7c/0x110 mdio_driver_register+0x24/0x58 do_one_initcall+0x74/0x2e8 do_init_module+0x60/0x1d0 load_module+0x1968/0x1ff4 sys_finit_module+0x8c/0x98 ret_fast_syscall+0x0/0x28 0xbedf2ae8
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1 ---- ---- lock(&desc->request_mutex); lock(&chip->reg_lock); lock(&desc->request_mutex); lock(&chip->reg_lock);
&desc->request_mutex refer to two different mutex. #1 is the GPIO for the chip interrupt. #2 is the chained interrupt between global 1 and global 2.
Add lockdep classes to the GPIO interrupt to avoid this.
Reported-by: Russell King rmk+kernel@armlinux.org.uk Signed-off-by: Andrew Lunn andrew@lunn.ch Signed-off-by: David S. Miller davem@davemloft.net
Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/dsa/mv88e6xxx/chip.c | 8 ++++++++ 1 file changed, 8 insertions(+)
diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c index c078c791f481..dabe89968a78 100644 --- a/drivers/net/dsa/mv88e6xxx/chip.c +++ b/drivers/net/dsa/mv88e6xxx/chip.c @@ -442,12 +442,20 @@ static int mv88e6xxx_g1_irq_setup_common(struct mv88e6xxx_chip *chip)
static int mv88e6xxx_g1_irq_setup(struct mv88e6xxx_chip *chip) { + static struct lock_class_key lock_key; + static struct lock_class_key request_key; int err;
err = mv88e6xxx_g1_irq_setup_common(chip); if (err) return err;
+ /* These lock classes tells lockdep that global 1 irqs are in + * a different category than their parent GPIO, so it won't + * report false recursion. + */ + irq_set_lockdep_class(chip->irq, &lock_key, &request_key); + err = request_threaded_irq(chip->irq, NULL, mv88e6xxx_g1_irq_thread_fn, IRQF_ONESHOT,