From: Andrew Lunn Date: Sat, 23 Feb 2019 16:43:56 +0000 (+0100) Subject: net: dsa: mv88e6xxx: Add lockdep classes to fix false positive splat X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=f6d9758b12660484b6639364cc406da92a918c96;p=openwrt%2Fstaging%2Fblogic.git net: dsa: mv88e6xxx: Add lockdep classes to fix false positive splat 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 Signed-off-by: Andrew Lunn Signed-off-by: David S. Miller --- diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c index 3f9a3fc52a0e..3546c5e2b924 100644 --- a/drivers/net/dsa/mv88e6xxx/chip.c +++ b/drivers/net/dsa/mv88e6xxx/chip.c @@ -442,12 +442,20 @@ out_mapping: 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 | IRQF_SHARED,