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 --- net/bluetooth/leds.c | 100 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 100 insertions(+) create mode 100644 net/bluetooth/leds.c (limited to 'net/bluetooth/leds.c') diff --git a/net/bluetooth/leds.c b/net/bluetooth/leds.c new file mode 100644 index 000000000..6e349704e --- /dev/null +++ b/net/bluetooth/leds.c @@ -0,0 +1,100 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright 2015, Heiner Kallweit + */ + +#include +#include + +#include "leds.h" + +DEFINE_LED_TRIGGER(bt_power_led_trigger); + +struct hci_basic_led_trigger { + struct led_trigger led_trigger; + struct hci_dev *hdev; +}; + +#define to_hci_basic_led_trigger(arg) container_of(arg, \ + struct hci_basic_led_trigger, led_trigger) + +void hci_leds_update_powered(struct hci_dev *hdev, bool enabled) +{ + if (hdev->power_led) + led_trigger_event(hdev->power_led, + enabled ? LED_FULL : LED_OFF); + + if (!enabled) { + struct hci_dev *d; + + read_lock(&hci_dev_list_lock); + + list_for_each_entry(d, &hci_dev_list, list) { + if (test_bit(HCI_UP, &d->flags)) + enabled = true; + } + + read_unlock(&hci_dev_list_lock); + } + + led_trigger_event(bt_power_led_trigger, enabled ? LED_FULL : LED_OFF); +} + +static int power_activate(struct led_classdev *led_cdev) +{ + struct hci_basic_led_trigger *htrig; + bool powered; + + htrig = to_hci_basic_led_trigger(led_cdev->trigger); + powered = test_bit(HCI_UP, &htrig->hdev->flags); + + led_set_brightness(led_cdev, powered ? LED_FULL : LED_OFF); + + return 0; +} + +static struct led_trigger *led_allocate_basic(struct hci_dev *hdev, + int (*activate)(struct led_classdev *led_cdev), + const char *name) +{ + struct hci_basic_led_trigger *htrig; + + htrig = devm_kzalloc(&hdev->dev, sizeof(*htrig), GFP_KERNEL); + if (!htrig) + return NULL; + + htrig->hdev = hdev; + htrig->led_trigger.activate = activate; + htrig->led_trigger.name = devm_kasprintf(&hdev->dev, GFP_KERNEL, + "%s-%s", hdev->name, + name); + if (!htrig->led_trigger.name) + goto err_alloc; + + if (devm_led_trigger_register(&hdev->dev, &htrig->led_trigger)) + goto err_register; + + return &htrig->led_trigger; + +err_register: + devm_kfree(&hdev->dev, (void *)htrig->led_trigger.name); +err_alloc: + devm_kfree(&hdev->dev, htrig); + return NULL; +} + +void hci_leds_init(struct hci_dev *hdev) +{ + /* initialize power_led */ + hdev->power_led = led_allocate_basic(hdev, power_activate, "power"); +} + +void bt_leds_init(void) +{ + led_trigger_register_simple("bluetooth-power", &bt_power_led_trigger); +} + +void bt_leds_cleanup(void) +{ + led_trigger_unregister_simple(bt_power_led_trigger); +} -- cgit v1.3.1