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-gembird.c | 113 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 113 insertions(+) create mode 100644 drivers/hid/hid-gembird.c (limited to 'drivers/hid/hid-gembird.c') diff --git a/drivers/hid/hid-gembird.c b/drivers/hid/hid-gembird.c new file mode 100644 index 000000000..20a8de766 --- /dev/null +++ b/drivers/hid/hid-gembird.c @@ -0,0 +1,113 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * HID driver for Gembird Joypad, "PC Game Controller" + * + * Copyright (c) 2015 Red Hat, Inc + * Copyright (c) 2015 Benjamin Tissoires + */ + +/* + */ + +#include +#include +#include + +#include "hid-ids.h" + +#define GEMBIRD_START_FAULTY_RDESC 8 + +static const __u8 gembird_jpd_faulty_rdesc[] = { + 0x75, 0x08, /* Report Size (8) */ + 0x95, 0x05, /* Report Count (5) */ + 0x15, 0x00, /* Logical Minimum (0) */ + 0x26, 0xff, 0x00, /* Logical Maximum (255) */ + 0x35, 0x00, /* Physical Minimum (0) */ + 0x46, 0xff, 0x00, /* Physical Maximum (255) */ + 0x09, 0x30, /* Usage (X) */ + 0x09, 0x31, /* Usage (Y) */ + 0x09, 0x32, /* Usage (Z) */ + 0x09, 0x32, /* Usage (Z) */ + 0x09, 0x35, /* Usage (Rz) */ + 0x81, 0x02, /* Input (Data,Var,Abs) */ +}; + +/* + * we fix the report descriptor by: + * - marking the first Z axis as constant (so it is ignored by HID) + * - assign the original second Z to Rx + * - assign the original Rz to Ry + */ +static const __u8 gembird_jpd_fixed_rdesc[] = { + 0x75, 0x08, /* Report Size (8) */ + 0x95, 0x02, /* Report Count (2) */ + 0x15, 0x00, /* Logical Minimum (0) */ + 0x26, 0xff, 0x00, /* Logical Maximum (255) */ + 0x35, 0x00, /* Physical Minimum (0) */ + 0x46, 0xff, 0x00, /* Physical Maximum (255) */ + 0x09, 0x30, /* Usage (X) */ + 0x09, 0x31, /* Usage (Y) */ + 0x81, 0x02, /* Input (Data,Var,Abs) */ + 0x95, 0x01, /* Report Count (1) */ + 0x09, 0x32, /* Usage (Z) */ + 0x81, 0x01, /* Input (Cnst,Arr,Abs) */ + 0x95, 0x02, /* Report Count (2) */ + 0x09, 0x33, /* Usage (Rx) */ + 0x09, 0x34, /* Usage (Ry) */ + 0x81, 0x02, /* Input (Data,Var,Abs) */ +}; + +static const __u8 *gembird_report_fixup(struct hid_device *hdev, __u8 *rdesc, + unsigned int *rsize) +{ + __u8 *new_rdesc; + /* delta_size is > 0 */ + size_t delta_size = sizeof(gembird_jpd_fixed_rdesc) - + sizeof(gembird_jpd_faulty_rdesc); + size_t new_size = *rsize + delta_size; + + if (*rsize >= 31 && !memcmp(&rdesc[GEMBIRD_START_FAULTY_RDESC], + gembird_jpd_faulty_rdesc, + sizeof(gembird_jpd_faulty_rdesc))) { + new_rdesc = devm_kzalloc(&hdev->dev, new_size, GFP_KERNEL); + if (new_rdesc == NULL) + return rdesc; + + dev_info(&hdev->dev, + "fixing Gembird JPD-DualForce 2 report descriptor.\n"); + + /* start by copying the end of the rdesc */ + memcpy(new_rdesc + delta_size, rdesc, *rsize); + + /* add the correct beginning */ + memcpy(new_rdesc, rdesc, GEMBIRD_START_FAULTY_RDESC); + + /* replace the faulty part with the fixed one */ + memcpy(new_rdesc + GEMBIRD_START_FAULTY_RDESC, + gembird_jpd_fixed_rdesc, + sizeof(gembird_jpd_fixed_rdesc)); + + *rsize = new_size; + rdesc = new_rdesc; + } + + return rdesc; +} + +static const struct hid_device_id gembird_devices[] = { + { HID_USB_DEVICE(USB_VENDOR_ID_GEMBIRD, + USB_DEVICE_ID_GEMBIRD_JPD_DUALFORCE2) }, + { } +}; +MODULE_DEVICE_TABLE(hid, gembird_devices); + +static struct hid_driver gembird_driver = { + .name = "gembird", + .id_table = gembird_devices, + .report_fixup = gembird_report_fixup, +}; +module_hid_driver(gembird_driver); + +MODULE_AUTHOR("Benjamin Tissoires "); +MODULE_DESCRIPTION("HID Gembird joypad driver"); +MODULE_LICENSE("GPL"); -- cgit v1.3.1