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-emsff.c | 115 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 115 insertions(+) create mode 100644 drivers/hid/hid-emsff.c (limited to 'drivers/hid/hid-emsff.c') diff --git a/drivers/hid/hid-emsff.c b/drivers/hid/hid-emsff.c new file mode 100644 index 000000000..d8e559e05 --- /dev/null +++ b/drivers/hid/hid-emsff.c @@ -0,0 +1,115 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Force feedback support for EMS Trio Linker Plus II + * + * Copyright (c) 2010 Ignaz Forster + */ + +/* + */ + + +#include +#include +#include + +#include "hid-ids.h" + +struct emsff_device { + struct hid_report *report; +}; + +static int emsff_play(struct input_dev *dev, void *data, + struct ff_effect *effect) +{ + struct hid_device *hid = input_get_drvdata(dev); + struct emsff_device *emsff = data; + int weak, strong; + + weak = effect->u.rumble.weak_magnitude; + strong = effect->u.rumble.strong_magnitude; + + dbg_hid("called with 0x%04x 0x%04x\n", strong, weak); + + weak = weak * 0xff / 0xffff; + strong = strong * 0xff / 0xffff; + + emsff->report->field[0]->value[1] = weak; + emsff->report->field[0]->value[2] = strong; + + dbg_hid("running with 0x%02x 0x%02x\n", strong, weak); + hid_hw_request(hid, emsff->report, HID_REQ_SET_REPORT); + + return 0; +} + +static int ems_input_configured(struct hid_device *hid, struct hid_input *hidinput) +{ + struct emsff_device *emsff; + struct hid_report *report; + struct list_head *report_list = + &hid->report_enum[HID_OUTPUT_REPORT].report_list; + struct input_dev *dev = hidinput->input; + int error; + + if (!list_is_first(&hidinput->list, &hid->inputs)) + return 0; + + report = list_first_entry_or_null(report_list, struct hid_report, list); + if (!report) { + hid_err(hid, "no output reports found\n"); + return -ENODEV; + } + if (report->maxfield < 1) { + hid_err(hid, "no fields in the report\n"); + return -ENODEV; + } + + if (report->field[0]->report_count < 7) { + hid_err(hid, "not enough values in the field\n"); + return -ENODEV; + } + + emsff = kzalloc_obj(struct emsff_device); + if (!emsff) + return -ENOMEM; + + emsff->report = report; + set_bit(FF_RUMBLE, dev->ffbit); + + error = input_ff_create_memless(dev, emsff, emsff_play); + if (error) { + kfree(emsff); + return error; + } + + emsff->report->field[0]->value[0] = 0x01; + emsff->report->field[0]->value[1] = 0x00; + emsff->report->field[0]->value[2] = 0x00; + emsff->report->field[0]->value[3] = 0x00; + emsff->report->field[0]->value[4] = 0x00; + emsff->report->field[0]->value[5] = 0x00; + emsff->report->field[0]->value[6] = 0x00; + hid_hw_request(hid, emsff->report, HID_REQ_SET_REPORT); + + hid_info(hid, "force feedback for EMS based devices by Ignaz Forster \n"); + + return 0; +} + +static const struct hid_device_id ems_devices[] = { + { HID_USB_DEVICE(USB_VENDOR_ID_EMS, USB_DEVICE_ID_EMS_TRIO_LINKER_PLUS_II) }, + { } +}; +MODULE_DEVICE_TABLE(hid, ems_devices); + +static struct hid_driver ems_driver = { + .name = "hkems", + .id_table = ems_devices, + .input_configured = ems_input_configured, +}; +module_hid_driver(ems_driver); + +MODULE_DESCRIPTION("Force feedback support for EMS Trio Linker Plus II"); +MODULE_LICENSE("GPL"); + -- cgit v1.3.1