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-wiimote-debug.c | 212 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 212 insertions(+) create mode 100644 drivers/hid/hid-wiimote-debug.c (limited to 'drivers/hid/hid-wiimote-debug.c') diff --git a/drivers/hid/hid-wiimote-debug.c b/drivers/hid/hid-wiimote-debug.c new file mode 100644 index 000000000..5f7491778 --- /dev/null +++ b/drivers/hid/hid-wiimote-debug.c @@ -0,0 +1,212 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Debug support for HID Nintendo Wii / Wii U peripherals + * Copyright (c) 2011-2013 David Herrmann + */ + +/* + */ + +#include +#include +#include +#include +#include +#include "hid-wiimote.h" + +struct wiimote_debug { + struct wiimote_data *wdata; + struct dentry *eeprom; + struct dentry *drm; +}; + +static ssize_t wiidebug_eeprom_read(struct file *f, char __user *u, size_t s, + loff_t *off) +{ + struct wiimote_debug *dbg = f->private_data; + struct wiimote_data *wdata = dbg->wdata; + unsigned long flags; + ssize_t ret; + char buf[16]; + __u16 size = 0; + + if (s == 0) + return -EINVAL; + if (*off > 0xffffff) + return 0; + if (s > 16) + s = 16; + + ret = wiimote_cmd_acquire(wdata); + if (ret) + return ret; + + spin_lock_irqsave(&wdata->state.lock, flags); + wdata->state.cmd_read_size = s; + wdata->state.cmd_read_buf = buf; + wiimote_cmd_set(wdata, WIIPROTO_REQ_RMEM, *off & 0xffff); + wiiproto_req_reeprom(wdata, *off, s); + spin_unlock_irqrestore(&wdata->state.lock, flags); + + ret = wiimote_cmd_wait(wdata); + if (!ret) + size = wdata->state.cmd_read_size; + + spin_lock_irqsave(&wdata->state.lock, flags); + wdata->state.cmd_read_buf = NULL; + spin_unlock_irqrestore(&wdata->state.lock, flags); + + wiimote_cmd_release(wdata); + + if (ret) + return ret; + else if (size == 0) + return -EIO; + + if (copy_to_user(u, buf, size)) + return -EFAULT; + + *off += size; + ret = size; + + return ret; +} + +static const struct file_operations wiidebug_eeprom_fops = { + .owner = THIS_MODULE, + .open = simple_open, + .read = wiidebug_eeprom_read, + .llseek = generic_file_llseek, +}; + +static const char *wiidebug_drmmap[] = { + [WIIPROTO_REQ_NULL] = "NULL", + [WIIPROTO_REQ_DRM_K] = "K", + [WIIPROTO_REQ_DRM_KA] = "KA", + [WIIPROTO_REQ_DRM_KE] = "KE", + [WIIPROTO_REQ_DRM_KAI] = "KAI", + [WIIPROTO_REQ_DRM_KEE] = "KEE", + [WIIPROTO_REQ_DRM_KAE] = "KAE", + [WIIPROTO_REQ_DRM_KIE] = "KIE", + [WIIPROTO_REQ_DRM_KAIE] = "KAIE", + [WIIPROTO_REQ_DRM_E] = "E", + [WIIPROTO_REQ_DRM_SKAI1] = "SKAI1", + [WIIPROTO_REQ_DRM_SKAI2] = "SKAI2", + [WIIPROTO_REQ_MAX] = NULL +}; + +static int wiidebug_drm_show(struct seq_file *f, void *p) +{ + struct wiimote_debug *dbg = f->private; + const char *str = NULL; + unsigned long flags; + __u8 drm; + + spin_lock_irqsave(&dbg->wdata->state.lock, flags); + drm = dbg->wdata->state.drm; + spin_unlock_irqrestore(&dbg->wdata->state.lock, flags); + + if (drm < WIIPROTO_REQ_MAX) + str = wiidebug_drmmap[drm]; + if (!str) + str = "unknown"; + + seq_printf(f, "%s\n", str); + + return 0; +} + +static int wiidebug_drm_open(struct inode *i, struct file *f) +{ + return single_open(f, wiidebug_drm_show, i->i_private); +} + +static ssize_t wiidebug_drm_write(struct file *f, const char __user *u, + size_t s, loff_t *off) +{ + struct seq_file *sf = f->private_data; + struct wiimote_debug *dbg = sf->private; + unsigned long flags; + char buf[16]; + ssize_t len; + int i; + + if (s == 0) + return -EINVAL; + + len = min((size_t) 15, s); + if (copy_from_user(buf, u, len)) + return -EFAULT; + + buf[len] = 0; + + for (i = 0; i < WIIPROTO_REQ_MAX; ++i) { + if (!wiidebug_drmmap[i]) + continue; + if (!strcasecmp(buf, wiidebug_drmmap[i])) + break; + } + + if (i == WIIPROTO_REQ_MAX) + i = simple_strtoul(buf, NULL, 16); + + spin_lock_irqsave(&dbg->wdata->state.lock, flags); + dbg->wdata->state.flags &= ~WIIPROTO_FLAG_DRM_LOCKED; + wiiproto_req_drm(dbg->wdata, (__u8) i); + if (i != WIIPROTO_REQ_NULL) + dbg->wdata->state.flags |= WIIPROTO_FLAG_DRM_LOCKED; + spin_unlock_irqrestore(&dbg->wdata->state.lock, flags); + + return len; +} + +static const struct file_operations wiidebug_drm_fops = { + .owner = THIS_MODULE, + .open = wiidebug_drm_open, + .read = seq_read, + .llseek = seq_lseek, + .write = wiidebug_drm_write, + .release = single_release, +}; + +int wiidebug_init(struct wiimote_data *wdata) +{ + struct wiimote_debug *dbg; + unsigned long flags; + + dbg = kzalloc_obj(*dbg); + if (!dbg) + return -ENOMEM; + + dbg->wdata = wdata; + + dbg->eeprom = debugfs_create_file("eeprom", S_IRUSR, + dbg->wdata->hdev->debug_dir, dbg, &wiidebug_eeprom_fops); + + dbg->drm = debugfs_create_file("drm", S_IRUSR, + dbg->wdata->hdev->debug_dir, dbg, &wiidebug_drm_fops); + + spin_lock_irqsave(&wdata->state.lock, flags); + wdata->debug = dbg; + spin_unlock_irqrestore(&wdata->state.lock, flags); + + return 0; + +} + +void wiidebug_deinit(struct wiimote_data *wdata) +{ + struct wiimote_debug *dbg = wdata->debug; + unsigned long flags; + + if (!dbg) + return; + + spin_lock_irqsave(&wdata->state.lock, flags); + wdata->debug = NULL; + spin_unlock_irqrestore(&wdata->state.lock, flags); + + debugfs_remove(dbg->drm); + debugfs_remove(dbg->eeprom); + kfree(dbg); +} -- cgit v1.3.1