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/nfc/hci/command.c | 344 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 344 insertions(+) create mode 100644 net/nfc/hci/command.c (limited to 'net/nfc/hci/command.c') diff --git a/net/nfc/hci/command.c b/net/nfc/hci/command.c new file mode 100644 index 000000000..af6bacb3b --- /dev/null +++ b/net/nfc/hci/command.c @@ -0,0 +1,344 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (C) 2012 Intel Corporation. All rights reserved. + */ + +#define pr_fmt(fmt) "hci: %s: " fmt, __func__ + +#include +#include +#include +#include + +#include + +#include "hci.h" + +#define MAX_FWI 4949 + +static int nfc_hci_execute_cmd_async(struct nfc_hci_dev *hdev, u8 pipe, u8 cmd, + const u8 *param, size_t param_len, + data_exchange_cb_t cb, void *cb_context) +{ + pr_debug("exec cmd async through pipe=%d, cmd=%d, plen=%zd\n", pipe, + cmd, param_len); + + /* TODO: Define hci cmd execution delay. Should it be the same + * for all commands? + */ + return nfc_hci_hcp_message_tx(hdev, pipe, NFC_HCI_HCP_COMMAND, cmd, + param, param_len, cb, cb_context, MAX_FWI); +} + +/* + * HCI command execution completion callback. + * err will be a standard linux error (may be converted from HCI response) + * skb contains the response data and must be disposed, or may be NULL if + * an error occurred + */ +static void nfc_hci_execute_cb(void *context, struct sk_buff *skb, int err) +{ + struct hcp_exec_waiter *hcp_ew = (struct hcp_exec_waiter *)context; + + pr_debug("HCI Cmd completed with result=%d\n", err); + + hcp_ew->exec_result = err; + if (hcp_ew->exec_result == 0) + hcp_ew->result_skb = skb; + else + kfree_skb(skb); + hcp_ew->exec_complete = true; + + wake_up(hcp_ew->wq); +} + +static int nfc_hci_execute_cmd(struct nfc_hci_dev *hdev, u8 pipe, u8 cmd, + const u8 *param, size_t param_len, + struct sk_buff **skb) +{ + DECLARE_WAIT_QUEUE_HEAD_ONSTACK(ew_wq); + struct hcp_exec_waiter hcp_ew; + hcp_ew.wq = &ew_wq; + hcp_ew.exec_complete = false; + hcp_ew.result_skb = NULL; + + pr_debug("exec cmd sync through pipe=%d, cmd=%d, plen=%zd\n", pipe, + cmd, param_len); + + /* TODO: Define hci cmd execution delay. Should it be the same + * for all commands? + */ + hcp_ew.exec_result = nfc_hci_hcp_message_tx(hdev, pipe, + NFC_HCI_HCP_COMMAND, cmd, + param, param_len, + nfc_hci_execute_cb, &hcp_ew, + MAX_FWI); + if (hcp_ew.exec_result < 0) + return hcp_ew.exec_result; + + wait_event(ew_wq, hcp_ew.exec_complete == true); + + if (hcp_ew.exec_result == 0) { + if (skb) + *skb = hcp_ew.result_skb; + else + kfree_skb(hcp_ew.result_skb); + } + + return hcp_ew.exec_result; +} + +int nfc_hci_send_event(struct nfc_hci_dev *hdev, u8 gate, u8 event, + const u8 *param, size_t param_len) +{ + u8 pipe; + + pr_debug("%d to gate %d\n", event, gate); + + pipe = hdev->gate2pipe[gate]; + if (pipe == NFC_HCI_INVALID_PIPE) + return -EADDRNOTAVAIL; + + return nfc_hci_hcp_message_tx(hdev, pipe, NFC_HCI_HCP_EVENT, event, + param, param_len, NULL, NULL, 0); +} +EXPORT_SYMBOL(nfc_hci_send_event); + +/* + * Execute an hci command sent to gate. + * skb will contain response data if success. skb can be NULL if you are not + * interested by the response. + */ +int nfc_hci_send_cmd(struct nfc_hci_dev *hdev, u8 gate, u8 cmd, + const u8 *param, size_t param_len, struct sk_buff **skb) +{ + u8 pipe; + + pipe = hdev->gate2pipe[gate]; + if (pipe == NFC_HCI_INVALID_PIPE) + return -EADDRNOTAVAIL; + + return nfc_hci_execute_cmd(hdev, pipe, cmd, param, param_len, skb); +} +EXPORT_SYMBOL(nfc_hci_send_cmd); + +int nfc_hci_send_cmd_async(struct nfc_hci_dev *hdev, u8 gate, u8 cmd, + const u8 *param, size_t param_len, + data_exchange_cb_t cb, void *cb_context) +{ + u8 pipe; + + pipe = hdev->gate2pipe[gate]; + if (pipe == NFC_HCI_INVALID_PIPE) + return -EADDRNOTAVAIL; + + return nfc_hci_execute_cmd_async(hdev, pipe, cmd, param, param_len, + cb, cb_context); +} +EXPORT_SYMBOL(nfc_hci_send_cmd_async); + +int nfc_hci_set_param(struct nfc_hci_dev *hdev, u8 gate, u8 idx, + const u8 *param, size_t param_len) +{ + int r; + u8 *tmp; + + /* TODO ELa: reg idx must be inserted before param, but we don't want + * to ask the caller to do it to keep a simpler API. + * For now, just create a new temporary param buffer. This is far from + * optimal though, and the plan is to modify APIs to pass idx down to + * nfc_hci_hcp_message_tx where the frame is actually built, thereby + * eliminating the need for the temp allocation-copy here. + */ + + pr_debug("idx=%d to gate %d\n", idx, gate); + + tmp = kmalloc(1 + param_len, GFP_KERNEL); + if (tmp == NULL) + return -ENOMEM; + + *tmp = idx; + memcpy(tmp + 1, param, param_len); + + r = nfc_hci_send_cmd(hdev, gate, NFC_HCI_ANY_SET_PARAMETER, + tmp, param_len + 1, NULL); + + kfree(tmp); + + return r; +} +EXPORT_SYMBOL(nfc_hci_set_param); + +int nfc_hci_get_param(struct nfc_hci_dev *hdev, u8 gate, u8 idx, + struct sk_buff **skb) +{ + pr_debug("gate=%d regidx=%d\n", gate, idx); + + return nfc_hci_send_cmd(hdev, gate, NFC_HCI_ANY_GET_PARAMETER, + &idx, 1, skb); +} +EXPORT_SYMBOL(nfc_hci_get_param); + +static int nfc_hci_open_pipe(struct nfc_hci_dev *hdev, u8 pipe) +{ + struct sk_buff *skb; + int r; + + pr_debug("pipe=%d\n", pipe); + + r = nfc_hci_execute_cmd(hdev, pipe, NFC_HCI_ANY_OPEN_PIPE, + NULL, 0, &skb); + if (r == 0) { + /* dest host other than host controller will send + * number of pipes already open on this gate before + * execution. The number can be found in skb->data[0] + */ + kfree_skb(skb); + } + + return r; +} + +static int nfc_hci_close_pipe(struct nfc_hci_dev *hdev, u8 pipe) +{ + return nfc_hci_execute_cmd(hdev, pipe, NFC_HCI_ANY_CLOSE_PIPE, + NULL, 0, NULL); +} + +static u8 nfc_hci_create_pipe(struct nfc_hci_dev *hdev, u8 dest_host, + u8 dest_gate, int *result) +{ + struct sk_buff *skb; + struct hci_create_pipe_params params; + struct hci_create_pipe_resp *resp; + u8 pipe; + + pr_debug("gate=%d\n", dest_gate); + + params.src_gate = NFC_HCI_ADMIN_GATE; + params.dest_host = dest_host; + params.dest_gate = dest_gate; + + *result = nfc_hci_execute_cmd(hdev, NFC_HCI_ADMIN_PIPE, + NFC_HCI_ADM_CREATE_PIPE, + (u8 *) ¶ms, sizeof(params), &skb); + if (*result < 0) + return NFC_HCI_INVALID_PIPE; + + resp = (struct hci_create_pipe_resp *)skb->data; + pipe = resp->pipe; + kfree_skb(skb); + + pr_debug("pipe created=%d\n", pipe); + + return pipe; +} + +static int nfc_hci_delete_pipe(struct nfc_hci_dev *hdev, u8 pipe) +{ + return nfc_hci_execute_cmd(hdev, NFC_HCI_ADMIN_PIPE, + NFC_HCI_ADM_DELETE_PIPE, &pipe, 1, NULL); +} + +static int nfc_hci_clear_all_pipes(struct nfc_hci_dev *hdev) +{ + u8 param[2]; + size_t param_len = 2; + + /* TODO: Find out what the identity reference data is + * and fill param with it. HCI spec 6.1.3.5 */ + + if (test_bit(NFC_HCI_QUIRK_SHORT_CLEAR, &hdev->quirks)) + param_len = 0; + + return nfc_hci_execute_cmd(hdev, NFC_HCI_ADMIN_PIPE, + NFC_HCI_ADM_CLEAR_ALL_PIPE, param, param_len, + NULL); +} + +int nfc_hci_disconnect_gate(struct nfc_hci_dev *hdev, u8 gate) +{ + int r; + u8 pipe = hdev->gate2pipe[gate]; + + if (pipe == NFC_HCI_INVALID_PIPE) + return -EADDRNOTAVAIL; + + r = nfc_hci_close_pipe(hdev, pipe); + if (r < 0) + return r; + + if (pipe != NFC_HCI_LINK_MGMT_PIPE && pipe != NFC_HCI_ADMIN_PIPE) { + r = nfc_hci_delete_pipe(hdev, pipe); + if (r < 0) + return r; + } + + hdev->gate2pipe[gate] = NFC_HCI_INVALID_PIPE; + + return 0; +} +EXPORT_SYMBOL(nfc_hci_disconnect_gate); + +int nfc_hci_disconnect_all_gates(struct nfc_hci_dev *hdev) +{ + int r; + + r = nfc_hci_clear_all_pipes(hdev); + if (r < 0) + return r; + + nfc_hci_reset_pipes(hdev); + + return 0; +} +EXPORT_SYMBOL(nfc_hci_disconnect_all_gates); + +int nfc_hci_connect_gate(struct nfc_hci_dev *hdev, u8 dest_host, u8 dest_gate, + u8 pipe) +{ + bool pipe_created = false; + int r; + + if (pipe == NFC_HCI_DO_NOT_CREATE_PIPE) + return 0; + + if (hdev->gate2pipe[dest_gate] != NFC_HCI_INVALID_PIPE) + return -EADDRINUSE; + + if (pipe != NFC_HCI_INVALID_PIPE) + goto open_pipe; + + switch (dest_gate) { + case NFC_HCI_LINK_MGMT_GATE: + pipe = NFC_HCI_LINK_MGMT_PIPE; + break; + case NFC_HCI_ADMIN_GATE: + pipe = NFC_HCI_ADMIN_PIPE; + break; + default: + pipe = nfc_hci_create_pipe(hdev, dest_host, dest_gate, &r); + if (pipe == NFC_HCI_INVALID_PIPE) + return r; + pipe_created = true; + break; + } + +open_pipe: + r = nfc_hci_open_pipe(hdev, pipe); + if (r < 0) { + if (pipe_created) + if (nfc_hci_delete_pipe(hdev, pipe) < 0) { + /* TODO: Cannot clean by deleting pipe... + * -> inconsistent state */ + } + return r; + } + + hdev->pipes[pipe].gate = dest_gate; + hdev->pipes[pipe].dest_host = dest_host; + hdev->gate2pipe[dest_gate] = pipe; + + return 0; +} +EXPORT_SYMBOL(nfc_hci_connect_gate); -- cgit v1.3.1