d98ce1f083
[ Upstream commit b1dfc0f76231bbf395c59d20a2070684620d5d0f ] Calling led_trigger_register() when attaching a PHY located on an SFP module potentially (and practically) leads into a deadlock. Fix this by not calling led_trigger_register() for PHYs localted on SFP modules as such modules actually never got any LEDs. ====================================================== WARNING: possible circular locking dependency detected 6.7.0-rc4-next-20231208+ #0 Tainted: G O ------------------------------------------------------ kworker/u8:2/43 is trying to acquire lock: ffffffc08108c4e8 (triggers_list_lock){++++}-{3:3}, at: led_trigger_register+0x4c/0x1a8 but task is already holding lock: ffffff80c5c6f318 (&sfp->sm_mutex){+.+.}-{3:3}, at: cleanup_module+0x2ba8/0x3120 [sfp] which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (&sfp->sm_mutex){+.+.}-{3:3}: __mutex_lock+0x88/0x7a0 mutex_lock_nested+0x20/0x28 cleanup_module+0x2ae0/0x3120 [sfp] sfp_register_bus+0x5c/0x9c sfp_register_socket+0x48/0xd4 cleanup_module+0x271c/0x3120 [sfp] platform_probe+0x64/0xb8 really_probe+0x17c/0x3c0 __driver_probe_device+0x78/0x164 driver_probe_device+0x3c/0xd4 __driver_attach+0xec/0x1f0 bus_for_each_dev+0x60/0xa0 driver_attach+0x20/0x28 bus_add_driver+0x108/0x208 driver_register+0x5c/0x118 __platform_driver_register+0x24/0x2c init_module+0x28/0xa7c [sfp] do_one_initcall+0x70/0x2ec do_init_module+0x54/0x1e4 load_module+0x1b78/0x1c8c __do_sys_init_module+0x1bc/0x2cc __arm64_sys_init_module+0x18/0x20 invoke_syscall.constprop.0+0x4c/0xdc do_el0_svc+0x3c/0xbc el0_svc+0x34/0x80 el0t_64_sync_handler+0xf8/0x124 el0t_64_sync+0x150/0x154 -> #2 (rtnl_mutex){+.+.}-{3:3}: __mutex_lock+0x88/0x7a0 mutex_lock_nested+0x20/0x28 rtnl_lock+0x18/0x20 set_device_name+0x30/0x130 netdev_trig_activate+0x13c/0x1ac led_trigger_set+0x118/0x234 led_trigger_write+0x104/0x17c sysfs_kf_bin_write+0x64/0x80 kernfs_fop_write_iter+0x128/0x1b4 vfs_write+0x178/0x2a4 ksys_write+0x58/0xd4 __arm64_sys_write+0x18/0x20 invoke_syscall.constprop.0+0x4c/0xdc do_el0_svc+0x3c/0xbc el0_svc+0x34/0x80 el0t_64_sync_handler+0xf8/0x124 el0t_64_sync+0x150/0x154 -> #1 (&led_cdev->trigger_lock){++++}-{3:3}: down_write+0x4c/0x13c led_trigger_write+0xf8/0x17c sysfs_kf_bin_write+0x64/0x80 kernfs_fop_write_iter+0x128/0x1b4 vfs_write+0x178/0x2a4 ksys_write+0x58/0xd4 __arm64_sys_write+0x18/0x20 invoke_syscall.constprop.0+0x4c/0xdc do_el0_svc+0x3c/0xbc el0_svc+0x34/0x80 el0t_64_sync_handler+0xf8/0x124 el0t_64_sync+0x150/0x154 -> #0 (triggers_list_lock){++++}-{3:3}: __lock_acquire+0x12a0/0x2014 lock_acquire+0x100/0x2ac down_write+0x4c/0x13c led_trigger_register+0x4c/0x1a8 phy_led_triggers_register+0x9c/0x214 phy_attach_direct+0x154/0x36c phylink_attach_phy+0x30/0x60 phylink_sfp_connect_phy+0x140/0x510 sfp_add_phy+0x34/0x50 init_module+0x15c/0xa7c [sfp] cleanup_module+0x1d94/0x3120 [sfp] cleanup_module+0x2bb4/0x3120 [sfp] process_one_work+0x1f8/0x4ec worker_thread+0x1e8/0x3d8 kthread+0x104/0x110 ret_from_fork+0x10/0x20 other info that might help us debug this: Chain exists of: triggers_list_lock --> rtnl_mutex --> &sfp->sm_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&sfp->sm_mutex); lock(rtnl_mutex); lock(&sfp->sm_mutex); lock(triggers_list_lock); *** DEADLOCK *** 4 locks held by kworker/u8:2/43: #0: ffffff80c000f938 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: process_one_work+0x150/0x4ec #1: ffffffc08214bde8 ((work_completion)(&(&sfp->timeout)->work)){+.+.}-{0:0}, at: process_one_work+0x150/0x4ec #2: ffffffc0810902f8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock+0x18/0x20 #3: ffffff80c5c6f318 (&sfp->sm_mutex){+.+.}-{3:3}, at: cleanup_module+0x2ba8/0x3120 [sfp] stack backtrace: CPU: 0 PID: 43 Comm: kworker/u8:2 Tainted: G O 6.7.0-rc4-next-20231208+ #0 Hardware name: Bananapi BPI-R4 (DT) Workqueue: events_power_efficient cleanup_module [sfp] Call trace: dump_backtrace+0xa8/0x10c show_stack+0x14/0x1c dump_stack_lvl+0x5c/0xa0 dump_stack+0x14/0x1c print_circular_bug+0x328/0x430 check_noncircular+0x124/0x134 __lock_acquire+0x12a0/0x2014 lock_acquire+0x100/0x2ac down_write+0x4c/0x13c led_trigger_register+0x4c/0x1a8 phy_led_triggers_register+0x9c/0x214 phy_attach_direct+0x154/0x36c phylink_attach_phy+0x30/0x60 phylink_sfp_connect_phy+0x140/0x510 sfp_add_phy+0x34/0x50 init_module+0x15c/0xa7c [sfp] cleanup_module+0x1d94/0x3120 [sfp] cleanup_module+0x2bb4/0x3120 [sfp] process_one_work+0x1f8/0x4ec worker_thread+0x1e8/0x3d8 kthread+0x104/0x110 ret_from_fork+0x10/0x20 Signed-off-by: Daniel Golle <daniel@makrotopia.org> Fixes: 01e5b728e9e4 ("net: phy: Add a binding for PHY LEDs") Link: https://lore.kernel.org/r/102a9dce38bdf00215735d04cd4704458273ad9c.1702339354.git.daniel@makrotopia.org Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
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