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/eir.h | 99 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 99 insertions(+) create mode 100644 net/bluetooth/eir.h (limited to 'net/bluetooth/eir.h') diff --git a/net/bluetooth/eir.h b/net/bluetooth/eir.h new file mode 100644 index 000000000..9372db83f --- /dev/null +++ b/net/bluetooth/eir.h @@ -0,0 +1,99 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * BlueZ - Bluetooth protocol stack for Linux + * + * Copyright (C) 2021 Intel Corporation + */ + +#include + +void eir_create(struct hci_dev *hdev, u8 *data); + +u8 eir_create_adv_data(struct hci_dev *hdev, u8 instance, u8 *ptr, u8 size); +u8 eir_create_scan_rsp(struct hci_dev *hdev, u8 instance, u8 *ptr); +u8 eir_create_per_adv_data(struct hci_dev *hdev, u8 instance, u8 *ptr); + +u8 eir_append_local_name(struct hci_dev *hdev, u8 *eir, u8 ad_len); +u8 eir_append_appearance(struct hci_dev *hdev, u8 *ptr, u8 ad_len); +u8 eir_append_service_data(u8 *eir, u16 eir_len, u16 uuid, u8 *data, + u8 data_len); + +static inline u16 eir_precalc_len(u8 data_len) +{ + return sizeof(u8) * 2 + data_len; +} + +static inline u16 eir_append_data(u8 *eir, u16 eir_len, u8 type, + u8 *data, u8 data_len) +{ + eir[eir_len++] = sizeof(type) + data_len; + eir[eir_len++] = type; + memcpy(&eir[eir_len], data, data_len); + eir_len += data_len; + + return eir_len; +} + +static inline u16 eir_append_le16(u8 *eir, u16 eir_len, u8 type, u16 data) +{ + eir[eir_len++] = sizeof(type) + sizeof(data); + eir[eir_len++] = type; + put_unaligned_le16(data, &eir[eir_len]); + eir_len += sizeof(data); + + return eir_len; +} + +static inline u16 eir_skb_put_data(struct sk_buff *skb, u8 type, u8 *data, u8 data_len) +{ + u8 *eir; + u16 eir_len; + + eir_len = eir_precalc_len(data_len); + eir = skb_put(skb, eir_len); + WARN_ON(sizeof(type) + data_len > U8_MAX); + eir[0] = sizeof(type) + data_len; + eir[1] = type; + memcpy(&eir[2], data, data_len); + + return eir_len; +} + +static inline void *eir_get_data(u8 *eir, size_t eir_len, u8 type, + size_t *data_len) +{ + size_t parsed = 0; + + if (eir_len < 2) + return NULL; + + while (parsed < eir_len - 1) { + u8 field_len = eir[0]; + + if (field_len == 0) + break; + + parsed += field_len + 1; + + if (parsed > eir_len) + break; + + if (eir[1] != type) { + eir += field_len + 1; + continue; + } + + /* Zero length data */ + if (field_len == 1) + return NULL; + + if (data_len) + *data_len = field_len - 1; + + return &eir[2]; + } + + return NULL; +} + +void *eir_get_service_data(u8 *eir, size_t eir_len, u16 uuid, size_t *len); -- cgit v1.3.1