leds: trigger: Replace use of system_wq() with system_percpu_wq()

2025-11-13T15:55:39Z

Currently if a user enqueues a work item using schedule_delayed_work() the used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to schedule_work() that is using system_wq and queue_work(), that makes use again of WORK_CPU_UNBOUND. This lack of consistency cannot be addressed without refactoring the API. This patch continues the effort to refactor worqueue APIs, which has begun with the change introducing new workqueues and a new alloc_workqueue flag: commit 128ea9f6ccfb ("workqueue: Add system_percpu_wq and system_dfl_wq") commit 930c2ea566af ("workqueue: Add new WQ_PERCPU flag") system_wq should be the per-cpu workqueue, yet in this name nothing makes that clear, so replace system_wq with system_percpu_wq. The old wq (system_wq) will be kept for a few release cycles. Suggested-by: Tejun Heo Signed-off-by: Marco Crivellari Link: https://patch.msgid.link/20251105111924.141555-1-marco.crivellari@suse.com Signed-off-by: Lee Jones

leds: trigger: input-events: Rewrite to fix a serious locking issue

2024-06-26T15:56:12Z

The input subsystem registers LEDs with default triggers while holding the input_lock and input_register_handler() takes the input_lock this means that a triggers activate method cannot directly call input_register_handler() as the old ledtrig-input-events code is doing. The initial implementation of the input-events trigger mainly did not use the simple LED trigger mechanism because that mechanism had an issue with the initial state of a newly activated LED not matching the last led_trigger_event() call for the trigger. This issue has been fixed in commit 822c91e72eac ("leds: trigger: Store brightness set by led_trigger_event()"). Rewrite the "input-events" trigger to use the simple LED trigger mechanism, registering a single input_handler at module_init() time and using led_trigger_event() to set the brightness for all LEDs controlled by this trigger. Compared to the old code this looses the ability for the user to configure a different brightness for the on state then LED_FULL, this is standard for simple LED triggers and since this trigger is only in for-leds-next ATM losing that functionality is not a regression. This also changes the configurability of the LED off timeout from a per LED setting to a global setting (runtime modifiable module-parameter). Switching to registering a single input_handler at module_init() time fixes the following locking issue reported by lockdep: [ 2840.220145] usb 1-1.3: new low-speed USB device number 3 using xhci_hcd [ 2840.307172] usb 1-1.3: New USB device found, idVendor=0603, idProduct=0002, bcdDevice= 2.21 [ 2840.307375] usb 1-1.3: New USB device strings: Mfr=1, Product=2, SerialNumber=0 [ 2840.307423] usb 1-1.3: Product: USB Composite Device [ 2840.307456] usb 1-1.3: Manufacturer: SINO WEALTH [ 2840.333985] input: SINO WEALTH USB Composite Device as /devices/pci0000:00/0000:00:14.0/usb1/1-1/1-1.3/1-1.3:1.0/0003:0603:0002.0007/input/input19 [ 2840.386545] ====================================================== [ 2840.386549] WARNING: possible circular locking dependency detected [ 2840.386554] 6.10.0-rc1+ #97 Tainted: G C E [ 2840.386558] ------------------------------------------------------ [ 2840.386562] kworker/1:1/52 is trying to acquire lock: [ 2840.386566] ffff98fcf1629300 (&led_cdev->led_access){+.+.}-{3:3}, at: led_classdev_register_ext+0x1c6/0x380 [ 2840.386590] but task is already holding lock: [ 2840.386593] ffffffff88130cc8 (input_mutex){+.+.}-{3:3}, at: input_register_device.cold+0x47/0x150 [ 2840.386608] which lock already depends on the new lock. [ 2840.386611] the existing dependency chain (in reverse order) is: [ 2840.386615] -> #3 (input_mutex){+.+.}-{3:3}: [ 2840.386624] __mutex_lock+0x8c/0xc10 [ 2840.386634] input_register_handler+0x1c/0xf0 [ 2840.386641] 0xffffffffc142c437 [ 2840.386655] led_trigger_set+0x1e1/0x2e0 [ 2840.386661] led_trigger_register+0x170/0x1b0 [ 2840.386666] do_one_initcall+0x5e/0x3a0 [ 2840.386675] do_init_module+0x60/0x220 [ 2840.386683] __do_sys_init_module+0x15f/0x190 [ 2840.386689] do_syscall_64+0x93/0x180 [ 2840.386696] entry_SYSCALL_64_after_hwframe+0x76/0x7e [ 2840.386705] -> #2 (&led_cdev->trigger_lock){+.+.}-{3:3}: [ 2840.386714] down_write+0x3b/0xd0 [ 2840.386720] led_trigger_register+0x12c/0x1b0 [ 2840.386725] rfkill_register+0xec/0x340 [rfkill] [ 2840.386739] wiphy_register+0x82a/0x930 [cfg80211] [ 2840.386907] brcmf_cfg80211_attach+0xcbd/0x1430 [brcmfmac] [ 2840.386952] brcmf_attach+0x1ba/0x4c0 [brcmfmac] [ 2840.386991] brcmf_pcie_setup+0x899/0xc70 [brcmfmac] [ 2840.387030] brcmf_fw_request_done+0x13b/0x180 [brcmfmac] [ 2840.387070] request_firmware_work_func+0x3b/0x70 [ 2840.387078] process_one_work+0x21a/0x590 [ 2840.387085] worker_thread+0x1d1/0x3e0 [ 2840.387090] kthread+0xee/0x120 [ 2840.387096] ret_from_fork+0x30/0x50 [ 2840.387105] ret_from_fork_asm+0x1a/0x30 [ 2840.387112] -> #1 (leds_list_lock){++++}-{3:3}: [ 2840.387123] down_write+0x3b/0xd0 [ 2840.387129] led_classdev_register_ext+0x29e/0x380 [ 2840.387134] 0xffffffffc0e6b74c [ 2840.387143] platform_probe+0x40/0xa0 [ 2840.387151] really_probe+0xde/0x340 [ 2840.387157] __driver_probe_device+0x78/0x110 [ 2840.387162] driver_probe_device+0x1f/0xa0 [ 2840.387168] __driver_attach+0xba/0x1c0 [ 2840.387173] bus_for_each_dev+0x6b/0xb0 [ 2840.387180] bus_add_driver+0x111/0x1f0 [ 2840.387185] driver_register+0x6e/0xc0 [ 2840.387191] do_one_initcall+0x5e/0x3a0 [ 2840.387197] do_init_module+0x60/0x220 [ 2840.387204] __do_sys_init_module+0x15f/0x190 [ 2840.387210] do_syscall_64+0x93/0x180 [ 2840.387217] entry_SYSCALL_64_after_hwframe+0x76/0x7e [ 2840.387224] -> #0 (&led_cdev->led_access){+.+.}-{3:3}: [ 2840.387233] __lock_acquire+0x11c6/0x1f20 [ 2840.387239] lock_acquire+0xc8/0x2b0 [ 2840.387244] __mutex_lock+0x8c/0xc10 [ 2840.387251] led_classdev_register_ext+0x1c6/0x380 [ 2840.387256] input_leds_connect+0x139/0x260 [ 2840.387262] input_attach_handler.isra.0+0x75/0x90 [ 2840.387268] input_register_device.cold+0xa1/0x150 [ 2840.387274] hidinput_connect+0x848/0xb00 [ 2840.387280] hid_connect+0x567/0x5a0 [ 2840.387288] hid_hw_start+0x3f/0x60 [ 2840.387294] hid_device_probe+0x10d/0x190 [ 2840.387298] really_probe+0xde/0x340 [ 2840.387304] __driver_probe_device+0x78/0x110 [ 2840.387309] driver_probe_device+0x1f/0xa0 [ 2840.387314] __device_attach_driver+0x85/0x110 [ 2840.387320] bus_for_each_drv+0x78/0xc0 [ 2840.387326] __device_attach+0xb0/0x1b0 [ 2840.387332] bus_probe_device+0x94/0xb0 [ 2840.387337] device_add+0x64a/0x860 [ 2840.387343] hid_add_device+0xe5/0x240 [ 2840.387349] usbhid_probe+0x4bb/0x600 [ 2840.387356] usb_probe_interface+0xea/0x2b0 [ 2840.387363] really_probe+0xde/0x340 [ 2840.387368] __driver_probe_device+0x78/0x110 [ 2840.387373] driver_probe_device+0x1f/0xa0 [ 2840.387378] __device_attach_driver+0x85/0x110 [ 2840.387383] bus_for_each_drv+0x78/0xc0 [ 2840.387390] __device_attach+0xb0/0x1b0 [ 2840.387395] bus_probe_device+0x94/0xb0 [ 2840.387400] device_add+0x64a/0x860 [ 2840.387405] usb_set_configuration+0x5e8/0x880 [ 2840.387411] usb_generic_driver_probe+0x3e/0x60 [ 2840.387418] usb_probe_device+0x3d/0x120 [ 2840.387423] really_probe+0xde/0x340 [ 2840.387428] __driver_probe_device+0x78/0x110 [ 2840.387434] driver_probe_device+0x1f/0xa0 [ 2840.387439] __device_attach_driver+0x85/0x110 [ 2840.387444] bus_for_each_drv+0x78/0xc0 [ 2840.387451] __device_attach+0xb0/0x1b0 [ 2840.387456] bus_probe_device+0x94/0xb0 [ 2840.387461] device_add+0x64a/0x860 [ 2840.387466] usb_new_device.cold+0x141/0x38f [ 2840.387473] hub_event+0x1166/0x1980 [ 2840.387479] process_one_work+0x21a/0x590 [ 2840.387484] worker_thread+0x1d1/0x3e0 [ 2840.387488] kthread+0xee/0x120 [ 2840.387493] ret_from_fork+0x30/0x50 [ 2840.387500] ret_from_fork_asm+0x1a/0x30 [ 2840.387506] other info that might help us debug this: [ 2840.387509] Chain exists of: &led_cdev->led_access --> &led_cdev->trigger_lock --> input_mutex [ 2840.387520] Possible unsafe locking scenario: [ 2840.387523] CPU0 CPU1 [ 2840.387526] ---- ---- [ 2840.387529] lock(input_mutex); [ 2840.387534] lock(&led_cdev->trigger_lock); [ 2840.387540] lock(input_mutex); [ 2840.387545] lock(&led_cdev->led_access); [ 2840.387550] *** DEADLOCK *** [ 2840.387552] 7 locks held by kworker/1:1/52: [ 2840.387557] #0: ffff98fcc1d07148 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x4af/0x590 [ 2840.387570] #1: ffffb67e00213e60 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x1d5/0x590 [ 2840.387583] #2: ffff98fcc6582190 (&dev->mutex){....}-{3:3}, at: hub_event+0x57/0x1980 [ 2840.387596] #3: ffff98fccb3c6990 (&dev->mutex){....}-{3:3}, at: __device_attach+0x26/0x1b0 [ 2840.387610] #4: ffff98fcc5260960 (&dev->mutex){....}-{3:3}, at: __device_attach+0x26/0x1b0 [ 2840.387622] #5: ffff98fce3999a20 (&dev->mutex){....}-{3:3}, at: __device_attach+0x26/0x1b0 [ 2840.387635] #6: ffffffff88130cc8 (input_mutex){+.+.}-{3:3}, at: input_register_device.cold+0x47/0x150 [ 2840.387649] stack backtrace: [ 2840.387653] CPU: 1 PID: 52 Comm: kworker/1:1 Tainted: G C E 6.10.0-rc1+ #97 [ 2840.387659] Hardware name: Xiaomi Inc Mipad2/Mipad, BIOS MIPad-P4.X64.0043.R03.1603071414 03/07/2016 [ 2840.387665] Workqueue: usb_hub_wq hub_event [ 2840.387674] Call Trace: [ 2840.387681] [ 2840.387689] dump_stack_lvl+0x68/0x90 [ 2840.387700] check_noncircular+0x10d/0x120 [ 2840.387710] ? register_lock_class+0x38/0x480 [ 2840.387717] ? check_noncircular+0x74/0x120 [ 2840.387727] __lock_acquire+0x11c6/0x1f20 [ 2840.387736] lock_acquire+0xc8/0x2b0 [ 2840.387743] ? led_classdev_register_ext+0x1c6/0x380 [ 2840.387753] __mutex_lock+0x8c/0xc10 [ 2840.387760] ? led_classdev_register_ext+0x1c6/0x380 [ 2840.387766] ? _raw_spin_unlock_irqrestore+0x35/0x60 [ 2840.387773] ? klist_next+0x158/0x160 [ 2840.387781] ? led_classdev_register_ext+0x1c6/0x380 [ 2840.387787] ? lockdep_init_map_type+0x58/0x250 [ 2840.387796] ? led_classdev_register_ext+0x1c6/0x380 [ 2840.387802] led_classdev_register_ext+0x1c6/0x380 [ 2840.387810] ? kvasprintf+0x70/0xb0 [ 2840.387820] ? kasprintf+0x3e/0x50 [ 2840.387829] input_leds_connect+0x139/0x260 [ 2840.387838] input_attach_handler.isra.0+0x75/0x90 [ 2840.387846] input_register_device.cold+0xa1/0x150 [ 2840.387854] hidinput_connect+0x848/0xb00 [ 2840.387862] ? usbhid_start+0x45b/0x7b0 [ 2840.387870] hid_connect+0x567/0x5a0 [ 2840.387878] ? __mutex_unlock_slowpath+0x2d/0x260 [ 2840.387891] hid_hw_start+0x3f/0x60 [ 2840.387899] hid_device_probe+0x10d/0x190 [ 2840.387906] ? __pfx___device_attach_driver+0x10/0x10 [ 2840.387913] really_probe+0xde/0x340 [ 2840.387919] ? pm_runtime_barrier+0x50/0x90 [ 2840.387927] __driver_probe_device+0x78/0x110 [ 2840.387934] driver_probe_device+0x1f/0xa0 [ 2840.387941] __device_attach_driver+0x85/0x110 [ 2840.387949] bus_for_each_drv+0x78/0xc0 [ 2840.387959] __device_attach+0xb0/0x1b0 [ 2840.387967] bus_probe_device+0x94/0xb0 [ 2840.387974] device_add+0x64a/0x860 [ 2840.387982] ? __debugfs_create_file+0x14a/0x1c0 [ 2840.387993] hid_add_device+0xe5/0x240 [ 2840.388002] usbhid_probe+0x4bb/0x600 [ 2840.388013] usb_probe_interface+0xea/0x2b0 [ 2840.388021] ? __pfx___device_attach_driver+0x10/0x10 [ 2840.388028] really_probe+0xde/0x340 [ 2840.388034] ? pm_runtime_barrier+0x50/0x90 [ 2840.388040] __driver_probe_device+0x78/0x110 [ 2840.388048] driver_probe_device+0x1f/0xa0 [ 2840.388055] __device_attach_driver+0x85/0x110 [ 2840.388062] bus_for_each_drv+0x78/0xc0 [ 2840.388071] __device_attach+0xb0/0x1b0 [ 2840.388079] bus_probe_device+0x94/0xb0 [ 2840.388086] device_add+0x64a/0x860 [ 2840.388094] ? __mutex_unlock_slowpath+0x2d/0x260 [ 2840.388103] usb_set_configuration+0x5e8/0x880 [ 2840.388114] ? __pfx___device_attach_driver+0x10/0x10 [ 2840.388121] usb_generic_driver_probe+0x3e/0x60 [ 2840.388129] usb_probe_device+0x3d/0x120 [ 2840.388137] really_probe+0xde/0x340 [ 2840.388142] ? pm_runtime_barrier+0x50/0x90 [ 2840.388149] __driver_probe_device+0x78/0x110 [ 2840.388156] driver_probe_device+0x1f/0xa0 [ 2840.388163] __device_attach_driver+0x85/0x110 [ 2840.388171] bus_for_each_drv+0x78/0xc0 [ 2840.388180] __device_attach+0xb0/0x1b0 [ 2840.388188] bus_probe_device+0x94/0xb0 [ 2840.388195] device_add+0x64a/0x860 [ 2840.388202] ? lockdep_hardirqs_on+0x78/0x100 [ 2840.388210] ? _raw_spin_unlock_irqrestore+0x35/0x60 [ 2840.388219] usb_new_device.cold+0x141/0x38f [ 2840.388227] hub_event+0x1166/0x1980 [ 2840.388242] process_one_work+0x21a/0x590 [ 2840.388249] ? move_linked_works+0x70/0xa0 [ 2840.388260] worker_thread+0x1d1/0x3e0 [ 2840.388268] ? __pfx_worker_thread+0x10/0x10 [ 2840.388273] kthread+0xee/0x120 [ 2840.388279] ? __pfx_kthread+0x10/0x10 [ 2840.388287] ret_from_fork+0x30/0x50 [ 2840.388294] ? __pfx_kthread+0x10/0x10 [ 2840.388301] ret_from_fork_asm+0x1a/0x30 [ 2840.388315] [ 2840.415630] hid-generic 0003:0603:0002.0007: input,hidraw6: USB HID v1.10 Keyboard [SINO WEALTH USB Composite Device] on usb-0000:00:14.0-1.3/input0 Signed-off-by: Hans de Goede Link: https://lore.kernel.org/r/20240602160203.27339-2-hdegoede@redhat.com Signed-off-by: Lee Jones

leds: trigger: Add new LED Input events trigger

2024-06-21T10:57:17Z

Add a new trigger which turns LEDs on when there is input (/dev/input/event*) activity and turns them back off again after there has been no activity for 5 seconds. This is primarily intended to control LED devices which are a backlight for capacitive touch-buttons, such as e.g. the menu / home / back buttons found on the bottom bezel of many somewhat older smartphones and tablets. This can also be used to turn on the keyboard backlight LED on input events and turn the keyboard backlight off again when idle. Signed-off-by: Hans de Goede Link: https://lore.kernel.org/r/20240531135910.168965-2-hdegoede@redhat.com Signed-off-by: Lee Jones

kernel/drivers/leds/trigger/ledtrig-input-events.c, branch linux-rolling-stable

leds: trigger: Replace use of system_wq() with system_percpu_wq()

leds: trigger: input-events: Rewrite to fix a serious locking issue

leds: trigger: Add new LED Input events trigger