From 0d6526f82c3cdefcca47f73f5fc08dc6f335eac6 Mon Sep 17 00:00:00 2001 From: Tim Chen Date: Mon, 21 Sep 2026 17:37:22 -0700 Subject: sched/cache: Keep nr_pref_llc_running in the runnable domain, to fix LLC mis-scheduling bug alb_break_llc() decides whether to break LLC preference during active load balance. It does so by testing that every runnable fair task on the source rq prefers its LLC: env->src_rq->nr_pref_llc_running == env->src_rq->cfs.h_nr_runnable But the two counters cover different sets. nr_pref_llc_running is updated in account_llc_enqueue()/account_llc_dequeue(), next to cfs_rq->nr_queued, so it follows queued tasks. h_nr_runnable is updated in set_delayed()/ clear_delayed() and drops delay-dequeued tasks. So under DELAY_DEQUEUE, a preferring task that goes to sleep stays counted in nr_pref_llc_running while h_nr_runnable falls. The equality then breaks, alb_break_llc() returns false, and active balance is free to pull a task off its preferred LLC. Active balance only moves runnable tasks, and this is the only LLC check it consults: once the stopper runs, LBF_ACTIVE_LB skips the per-task test in can_migrate_task(). The runnable set is the one we want. Fix it on the counter side. A task should be counted in nr_pref_llc_running exactly while it is both queued on its preferred LLC (pref_llc_queued) and runnable (!sched_delayed). Define that membership once in task_pref_llc_runnable(), and adjust the counter only through pref_llc_running_inc()/pref_llc_running_dec() from the four sites that change either input: account_llc_enqueue(), account_llc_dequeue(), set_delayed() and clear_delayed(). Gating every update on the same predicate keeps the delay, wake and dequeue paths from double-counting or underflowing; see the comments at those sites for the ordering. nr_llc_running and sd->llc_counts are not touched and stay on queued semantics. Fixes: 714059f79ff0 ("sched/cache: Handle moving single tasks to/from their preferred LLC") Closes: https://lore.kernel.org/lkml/20260827135000.735138-1-zhanxusheng@xiaomi.com/ Reported-by: Zhan Xusheng Suggested-by: Chen Yu Signed-off-by: Tim Chen Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Reviewed-by: Kayra Cizmeci Cc: # v7.2.x Link: https://patch.msgid.link/06af61afedac32e6477f57feb4d658f6c411c3af.1790035273.git.tim.c.chen@linux.intel.com --- drivers/input/keyboard/ipaq-micro-keys.c | 165 +++++++++++++++++++++++++++++++ 1 file changed, 165 insertions(+) create mode 100644 drivers/input/keyboard/ipaq-micro-keys.c (limited to 'drivers/input/keyboard/ipaq-micro-keys.c') diff --git a/drivers/input/keyboard/ipaq-micro-keys.c b/drivers/input/keyboard/ipaq-micro-keys.c new file mode 100644 index 000000000..ebd991de7 --- /dev/null +++ b/drivers/input/keyboard/ipaq-micro-keys.c @@ -0,0 +1,165 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * + * h3600 atmel micro companion support, key subdevice + * based on previous kernel 2.4 version + * Author : Alessandro Gardich + * Author : Linus Walleij + */ +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +static const u16 micro_keycodes[] = { + KEY_RECORD, /* 1: Record button */ + KEY_CALENDAR, /* 2: Calendar */ + KEY_ADDRESSBOOK, /* 3: Contacts (looks like Outlook) */ + KEY_MAIL, /* 4: Envelope (Q on older iPAQs) */ + KEY_HOMEPAGE, /* 5: Start (looks like swoopy arrow) */ + KEY_UP, /* 6: Up */ + KEY_RIGHT, /* 7: Right */ + KEY_LEFT, /* 8: Left */ + KEY_DOWN, /* 9: Down */ +}; + +struct ipaq_micro_keys { + struct ipaq_micro *micro; + struct input_dev *input; + u16 codes[ARRAY_SIZE(micro_keycodes)]; +}; + +static void micro_key_receive(void *data, int len, unsigned char *msg) +{ + struct ipaq_micro_keys *keys = data; + int key, down; + + if (len < 1) + return; + + down = 0x80 & msg[0]; + key = 0x7f & msg[0]; + + if (key < ARRAY_SIZE(micro_keycodes)) { + input_report_key(keys->input, keys->codes[key], down); + input_sync(keys->input); + } +} + +static void micro_key_start(struct ipaq_micro_keys *keys) +{ + guard(spinlock_irq)(&keys->micro->lock); + + keys->micro->key = micro_key_receive; + keys->micro->key_data = keys; +} + +static void micro_key_stop(struct ipaq_micro_keys *keys) +{ + guard(spinlock_irq)(&keys->micro->lock); + + keys->micro->key = NULL; + keys->micro->key_data = NULL; +} + +static int micro_key_open(struct input_dev *input) +{ + struct ipaq_micro_keys *keys = input_get_drvdata(input); + + micro_key_start(keys); + + return 0; +} + +static void micro_key_close(struct input_dev *input) +{ + struct ipaq_micro_keys *keys = input_get_drvdata(input); + + micro_key_stop(keys); +} + +static int micro_key_probe(struct platform_device *pdev) +{ + struct ipaq_micro_keys *keys; + int error; + int i; + + keys = devm_kzalloc(&pdev->dev, sizeof(*keys), GFP_KERNEL); + if (!keys) + return -ENOMEM; + + keys->micro = dev_get_drvdata(pdev->dev.parent); + + keys->input = devm_input_allocate_device(&pdev->dev); + if (!keys->input) + return -ENOMEM; + + keys->input->keycodesize = sizeof(micro_keycodes[0]); + keys->input->keycodemax = ARRAY_SIZE(micro_keycodes); + memcpy(keys->codes, micro_keycodes, sizeof(keys->codes)); + + keys->input->keycode = keys->codes; + + __set_bit(EV_KEY, keys->input->evbit); + for (i = 0; i < ARRAY_SIZE(micro_keycodes); i++) + __set_bit(micro_keycodes[i], keys->input->keybit); + + keys->input->name = "h3600 micro keys"; + keys->input->open = micro_key_open; + keys->input->close = micro_key_close; + input_set_drvdata(keys->input, keys); + + error = input_register_device(keys->input); + if (error) + return error; + + platform_set_drvdata(pdev, keys); + return 0; +} + +static int micro_key_suspend(struct device *dev) +{ + struct ipaq_micro_keys *keys = dev_get_drvdata(dev); + + micro_key_stop(keys); + + return 0; +} + +static int micro_key_resume(struct device *dev) +{ + struct ipaq_micro_keys *keys = dev_get_drvdata(dev); + struct input_dev *input = keys->input; + + guard(mutex)(&input->mutex); + + if (input_device_enabled(input)) + micro_key_start(keys); + + return 0; +} + +static DEFINE_SIMPLE_DEV_PM_OPS(micro_key_dev_pm_ops, + micro_key_suspend, micro_key_resume); + +static struct platform_driver micro_key_device_driver = { + .driver = { + .name = "ipaq-micro-keys", + .pm = pm_sleep_ptr(µ_key_dev_pm_ops), + }, + .probe = micro_key_probe, +}; +module_platform_driver(micro_key_device_driver); + +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("driver for iPAQ Atmel micro keys"); +MODULE_ALIAS("platform:ipaq-micro-keys"); -- cgit v1.3.1