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/hid/hid-hyperx.c | 117 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 117 insertions(+) create mode 100644 drivers/hid/hid-hyperx.c (limited to 'drivers/hid/hid-hyperx.c') diff --git a/drivers/hid/hid-hyperx.c b/drivers/hid/hid-hyperx.c new file mode 100644 index 000000000..18d2dc24c --- /dev/null +++ b/drivers/hid/hid-hyperx.c @@ -0,0 +1,117 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * HID driver for the HyperX QuadCast 2 microphone + * + * The tap-to-mute button is handled entirely in the device firmware: it gates + * the audio internally and does not send the Telephony "Phone Mute" usage its + * own report descriptor advertises. The resulting mute state is only reported + * through a vendor-defined collection, which hid-input cannot map, so the + * button is invisible to userspace. + * + * Copyright (c) 2026 Benjamin Blume + */ + +#include +#include +#include + +#include "hid-ids.h" + +#define HYPERX_QC2_REPORT_ID 0x77 +#define HYPERX_QC2_EVENT_MUTE 0x06 +#define HYPERX_QC2_MUTE_LEN 3 + +struct hyperx_drvdata { + struct input_dev *input; + bool muted; + bool have_state; +}; + +static int hyperx_input_configured(struct hid_device *hdev, + struct hid_input *hi) +{ + struct hyperx_drvdata *drvdata = hid_get_drvdata(hdev); + + /* + * The device exposes several application collections. Prefer the + * telephony one, which already advertises KEY_MICMUTE, and fall back + * to the first collection otherwise. + */ + if (!drvdata->input || test_bit(KEY_MICMUTE, hi->input->keybit)) { + drvdata->input = hi->input; + input_set_capability(drvdata->input, EV_KEY, KEY_MICMUTE); + } + + return 0; +} + +static int hyperx_raw_event(struct hid_device *hdev, struct hid_report *report, + u8 *data, int size) +{ + struct hyperx_drvdata *drvdata = hid_get_drvdata(hdev); + bool muted; + + if (!(hdev->claimed & HID_CLAIMED_INPUT) || !drvdata->input) + return 0; + + if (size < HYPERX_QC2_MUTE_LEN || data[0] != HYPERX_QC2_REPORT_ID || + data[1] != HYPERX_QC2_EVENT_MUTE) + return 0; + + muted = data[2]; + if (drvdata->have_state && muted == drvdata->muted) + return 0; + + drvdata->muted = muted; + drvdata->have_state = true; + + /* + * The device reports the resulting absolute state, while KEY_MICMUTE is + * a momentary key that userspace acts on as a toggle. Emit one + * keypress per state change. + */ + input_report_key(drvdata->input, KEY_MICMUTE, 1); + input_sync(drvdata->input); + input_report_key(drvdata->input, KEY_MICMUTE, 0); + input_sync(drvdata->input); + + return 0; +} + +static int hyperx_probe(struct hid_device *hdev, const struct hid_device_id *id) +{ + struct hyperx_drvdata *drvdata; + int ret; + + drvdata = devm_kzalloc(&hdev->dev, sizeof(*drvdata), GFP_KERNEL); + if (!drvdata) + return -ENOMEM; + + hid_set_drvdata(hdev, drvdata); + + ret = hid_parse(hdev); + if (ret) + return ret; + + return hid_hw_start(hdev, HID_CONNECT_DEFAULT); +} + +static const struct hid_device_id hyperx_devices[] = { + { HID_USB_DEVICE(USB_VENDOR_ID_HP, + USB_PRODUCT_ID_HP_HYPERX_QUADCAST_2) }, + { } +}; +MODULE_DEVICE_TABLE(hid, hyperx_devices); + +static struct hid_driver hyperx_driver = { + .name = "hyperx", + .id_table = hyperx_devices, + .probe = hyperx_probe, + .input_configured = hyperx_input_configured, + .raw_event = hyperx_raw_event, +}; +module_hid_driver(hyperx_driver); + +MODULE_DESCRIPTION("HID driver for the HyperX QuadCast 2 microphone"); +MODULE_AUTHOR("Benjamin Blume "); +MODULE_LICENSE("GPL"); -- cgit v1.3.1