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/input/misc/ad714x-i2c.c | 97 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 97 insertions(+) create mode 100644 drivers/input/misc/ad714x-i2c.c (limited to 'drivers/input/misc/ad714x-i2c.c') diff --git a/drivers/input/misc/ad714x-i2c.c b/drivers/input/misc/ad714x-i2c.c new file mode 100644 index 000000000..c3cb56151 --- /dev/null +++ b/drivers/input/misc/ad714x-i2c.c @@ -0,0 +1,97 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * AD714X CapTouch Programmable Controller driver (I2C bus) + * + * Copyright 2009-2011 Analog Devices Inc. + */ + +#include /* BUS_I2C */ +#include +#include +#include +#include +#include "ad714x.h" + +static int ad714x_i2c_write(struct ad714x_chip *chip, + unsigned short reg, unsigned short data) +{ + struct i2c_client *client = to_i2c_client(chip->dev); + int error; + + chip->xfer_buf[0] = cpu_to_be16(reg); + chip->xfer_buf[1] = cpu_to_be16(data); + + error = i2c_master_send(client, (u8 *)chip->xfer_buf, + 2 * sizeof(*chip->xfer_buf)); + if (unlikely(error < 0)) { + dev_err(&client->dev, "I2C write error: %d\n", error); + return error; + } + + return 0; +} + +static int ad714x_i2c_read(struct ad714x_chip *chip, + unsigned short reg, unsigned short *data, size_t len) +{ + struct i2c_client *client = to_i2c_client(chip->dev); + int i; + int error; + + chip->xfer_buf[0] = cpu_to_be16(reg); + + error = i2c_master_send(client, (u8 *)chip->xfer_buf, + sizeof(*chip->xfer_buf)); + if (error >= 0) + error = i2c_master_recv(client, (u8 *)chip->xfer_buf, + len * sizeof(*chip->xfer_buf)); + + if (unlikely(error < 0)) { + dev_err(&client->dev, "I2C read error: %d\n", error); + return error; + } + + for (i = 0; i < len; i++) + data[i] = be16_to_cpu(chip->xfer_buf[i]); + + return 0; +} + +static int ad714x_i2c_probe(struct i2c_client *client) +{ + struct ad714x_chip *chip; + + chip = ad714x_probe(&client->dev, BUS_I2C, client->irq, + ad714x_i2c_read, ad714x_i2c_write); + if (IS_ERR(chip)) + return PTR_ERR(chip); + + i2c_set_clientdata(client, chip); + + return 0; +} + +static const struct i2c_device_id ad714x_id[] = { + { .name = "ad7142_captouch" }, + { .name = "ad7143_captouch" }, + { .name = "ad7147_captouch" }, + { .name = "ad7147a_captouch" }, + { .name = "ad7148_captouch" }, + { } +}; +MODULE_DEVICE_TABLE(i2c, ad714x_id); + +static struct i2c_driver ad714x_i2c_driver = { + .driver = { + .name = "ad714x_captouch", + .pm = pm_sleep_ptr(&ad714x_pm), + }, + .probe = ad714x_i2c_probe, + .id_table = ad714x_id, +}; + +module_i2c_driver(ad714x_i2c_driver); + +MODULE_DESCRIPTION("Analog Devices AD714X Capacitance Touch Sensor I2C Bus Driver"); +MODULE_AUTHOR("Barry Song <21cnbao@gmail.com>"); +MODULE_LICENSE("GPL"); -- cgit v1.3.1