sched/cache: Keep nr_pref_llc_running in the runnable domain, to fix LLC mis-scheduling buggrafted

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 <zhanxusheng@xiaomi.com>
Suggested-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Kayra Cizmeci <kayracizmeci@gmail.com>
Cc: <stable@kernel.org> # v7.2.x
Link: https://patch.msgid.link/06af61afedac32e6477f57feb4d658f6c411c3af.1790035273.git.tim.c.chen@linux.intel.com

1 files changed, 280 insertions, 0 deletions

diff --git a/drivers/usb/phy/phy-ulpi.c b/drivers/usb/phy/phy-ulpi.c
new file mode 100644
index 000000000..4df63e67b
--- /dev/null
+++ b/drivers/usb/phy/phy-ulpi.c
@@ -0,0 +1,280 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Generic ULPI USB transceiver support
+ *
+ * Copyright (C) 2009 Daniel Mack <daniel@caiaq.de>
+ *
+ * Based on sources from
+ *
+ *   Sascha Hauer <s.hauer@pengutronix.de>
+ *   Freescale Semiconductors
+ */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/export.h>
+#include <linux/usb.h>
+#include <linux/usb/otg.h>
+#include <linux/usb/ulpi.h>
+
+
+struct ulpi_info {
+	unsigned int	id;
+	char		*name;
+};
+
+#define ULPI_ID(vendor, product) (((vendor) << 16) | (product))
+#define ULPI_INFO(_id, _name)		\
+	{				\
+		.id	= (_id),	\
+		.name	= (_name),	\
+	}
+
+/* ULPI hardcoded IDs, used for probing */
+static struct ulpi_info ulpi_ids[] = {
+	ULPI_INFO(ULPI_ID(0x04cc, 0x1504), "NXP ISP1504"),
+	ULPI_INFO(ULPI_ID(0x0424, 0x0006), "SMSC USB331x"),
+	ULPI_INFO(ULPI_ID(0x0424, 0x0007), "SMSC USB3320"),
+	ULPI_INFO(ULPI_ID(0x0424, 0x0009), "SMSC USB334x"),
+	ULPI_INFO(ULPI_ID(0x0451, 0x1507), "TI TUSB1210"),
+};
+
+static int ulpi_set_otg_flags(struct usb_phy *phy)
+{
+	unsigned int flags = ULPI_OTG_CTRL_DP_PULLDOWN |
+			     ULPI_OTG_CTRL_DM_PULLDOWN;
+
+	if (phy->flags & ULPI_OTG_ID_PULLUP)
+		flags |= ULPI_OTG_CTRL_ID_PULLUP;
+
+	/*
+	 * ULPI Specification rev.1.1 default
+	 * for Dp/DmPulldown is enabled.
+	 */
+	if (phy->flags & ULPI_OTG_DP_PULLDOWN_DIS)
+		flags &= ~ULPI_OTG_CTRL_DP_PULLDOWN;
+
+	if (phy->flags & ULPI_OTG_DM_PULLDOWN_DIS)
+		flags &= ~ULPI_OTG_CTRL_DM_PULLDOWN;
+
+	if (phy->flags & ULPI_OTG_EXTVBUSIND)
+		flags |= ULPI_OTG_CTRL_EXTVBUSIND;
+
+	return usb_phy_io_write(phy, flags, ULPI_OTG_CTRL);
+}
+
+static int ulpi_set_fc_flags(struct usb_phy *phy)
+{
+	unsigned int flags = 0;
+
+	/*
+	 * ULPI Specification rev.1.1 default
+	 * for XcvrSelect is Full Speed.
+	 */
+	if (phy->flags & ULPI_FC_HS)
+		flags |= ULPI_FUNC_CTRL_HIGH_SPEED;
+	else if (phy->flags & ULPI_FC_LS)
+		flags |= ULPI_FUNC_CTRL_LOW_SPEED;
+	else if (phy->flags & ULPI_FC_FS4LS)
+		flags |= ULPI_FUNC_CTRL_FS4LS;
+	else
+		flags |= ULPI_FUNC_CTRL_FULL_SPEED;
+
+	if (phy->flags & ULPI_FC_TERMSEL)
+		flags |= ULPI_FUNC_CTRL_TERMSELECT;
+
+	/*
+	 * ULPI Specification rev.1.1 default
+	 * for OpMode is Normal Operation.
+	 */
+	if (phy->flags & ULPI_FC_OP_NODRV)
+		flags |= ULPI_FUNC_CTRL_OPMODE_NONDRIVING;
+	else if (phy->flags & ULPI_FC_OP_DIS_NRZI)
+		flags |= ULPI_FUNC_CTRL_OPMODE_DISABLE_NRZI;
+	else if (phy->flags & ULPI_FC_OP_NSYNC_NEOP)
+		flags |= ULPI_FUNC_CTRL_OPMODE_NOSYNC_NOEOP;
+	else
+		flags |= ULPI_FUNC_CTRL_OPMODE_NORMAL;
+
+	/*
+	 * ULPI Specification rev.1.1 default
+	 * for SuspendM is Powered.
+	 */
+	flags |= ULPI_FUNC_CTRL_SUSPENDM;
+
+	return usb_phy_io_write(phy, flags, ULPI_FUNC_CTRL);
+}
+
+static int ulpi_set_ic_flags(struct usb_phy *phy)
+{
+	unsigned int flags = 0;
+
+	if (phy->flags & ULPI_IC_AUTORESUME)
+		flags |= ULPI_IFC_CTRL_AUTORESUME;
+
+	if (phy->flags & ULPI_IC_EXTVBUS_INDINV)
+		flags |= ULPI_IFC_CTRL_EXTERNAL_VBUS;
+
+	if (phy->flags & ULPI_IC_IND_PASSTHRU)
+		flags |= ULPI_IFC_CTRL_PASSTHRU;
+
+	if (phy->flags & ULPI_IC_PROTECT_DIS)
+		flags |= ULPI_IFC_CTRL_PROTECT_IFC_DISABLE;
+
+	return usb_phy_io_write(phy, flags, ULPI_IFC_CTRL);
+}
+
+static int ulpi_set_flags(struct usb_phy *phy)
+{
+	int ret;
+
+	ret = ulpi_set_otg_flags(phy);
+	if (ret)
+		return ret;
+
+	ret = ulpi_set_ic_flags(phy);
+	if (ret)
+		return ret;
+
+	return ulpi_set_fc_flags(phy);
+}
+
+static int ulpi_check_integrity(struct usb_phy *phy)
+{
+	int ret, i;
+	unsigned int val = 0x55;
+
+	for (i = 0; i < 2; i++) {
+		ret = usb_phy_io_write(phy, val, ULPI_SCRATCH);
+		if (ret < 0)
+			return ret;
+
+		ret = usb_phy_io_read(phy, ULPI_SCRATCH);
+		if (ret < 0)
+			return ret;
+
+		if (ret != val) {
+			pr_err("ULPI integrity check: failed!");
+			return -ENODEV;
+		}
+		val = val << 1;
+	}
+
+	pr_info("ULPI integrity check: passed.\n");
+
+	return 0;
+}
+
+static int ulpi_init(struct usb_phy *phy)
+{
+	int i, vid, pid, ret;
+	u32 ulpi_id = 0;
+
+	for (i = 0; i < 4; i++) {
+		ret = usb_phy_io_read(phy, ULPI_PRODUCT_ID_HIGH - i);
+		if (ret < 0)
+			return ret;
+		ulpi_id = (ulpi_id << 8) | ret;
+	}
+	vid = ulpi_id & 0xffff;
+	pid = ulpi_id >> 16;
+
+	pr_info("ULPI transceiver vendor/product ID 0x%04x/0x%04x\n", vid, pid);
+
+	for (i = 0; i < ARRAY_SIZE(ulpi_ids); i++) {
+		if (ulpi_ids[i].id == ULPI_ID(vid, pid)) {
+			pr_info("Found %s ULPI transceiver.\n",
+				ulpi_ids[i].name);
+			break;
+		}
+	}
+
+	ret = ulpi_check_integrity(phy);
+	if (ret)
+		return ret;
+
+	return ulpi_set_flags(phy);
+}
+
+static int ulpi_set_host(struct usb_otg *otg, struct usb_bus *host)
+{
+	struct usb_phy *phy = otg->usb_phy;
+	unsigned int flags = usb_phy_io_read(phy, ULPI_IFC_CTRL);
+
+	if (!host) {
+		otg->host = NULL;
+		return 0;
+	}
+
+	otg->host = host;
+
+	flags &= ~(ULPI_IFC_CTRL_6_PIN_SERIAL_MODE |
+		   ULPI_IFC_CTRL_3_PIN_SERIAL_MODE |
+		   ULPI_IFC_CTRL_CARKITMODE);
+
+	if (phy->flags & ULPI_IC_6PIN_SERIAL)
+		flags |= ULPI_IFC_CTRL_6_PIN_SERIAL_MODE;
+	else if (phy->flags & ULPI_IC_3PIN_SERIAL)
+		flags |= ULPI_IFC_CTRL_3_PIN_SERIAL_MODE;
+	else if (phy->flags & ULPI_IC_CARKIT)
+		flags |= ULPI_IFC_CTRL_CARKITMODE;
+
+	return usb_phy_io_write(phy, flags, ULPI_IFC_CTRL);
+}
+
+static int ulpi_set_vbus(struct usb_otg *otg, bool on)
+{
+	struct usb_phy *phy = otg->usb_phy;
+	unsigned int flags = usb_phy_io_read(phy, ULPI_OTG_CTRL);
+
+	flags &= ~(ULPI_OTG_CTRL_DRVVBUS | ULPI_OTG_CTRL_DRVVBUS_EXT);
+
+	if (on) {
+		if (phy->flags & ULPI_OTG_DRVVBUS)
+			flags |= ULPI_OTG_CTRL_DRVVBUS;
+
+		if (phy->flags & ULPI_OTG_DRVVBUS_EXT)
+			flags |= ULPI_OTG_CTRL_DRVVBUS_EXT;
+	}
+
+	return usb_phy_io_write(phy, flags, ULPI_OTG_CTRL);
+}
+
+static void otg_ulpi_init(struct usb_phy *phy, struct usb_otg *otg,
+			  struct usb_phy_io_ops *ops,
+			  unsigned int flags)
+{
+	phy->label	= "ULPI";
+	phy->flags	= flags;
+	phy->io_ops	= ops;
+	phy->otg	= otg;
+	phy->init	= ulpi_init;
+
+	otg->usb_phy	= phy;
+	otg->set_host	= ulpi_set_host;
+	otg->set_vbus	= ulpi_set_vbus;
+}
+
+struct usb_phy *
+devm_otg_ulpi_create(struct device *dev,
+		     struct usb_phy_io_ops *ops,
+		     unsigned int flags)
+{
+	struct usb_phy *phy;
+	struct usb_otg *otg;
+
+	phy = devm_kzalloc(dev, sizeof(*phy), GFP_KERNEL);
+	if (!phy)
+		return NULL;
+
+	otg = devm_kzalloc(dev, sizeof(*otg), GFP_KERNEL);
+	if (!otg) {
+		devm_kfree(dev, phy);
+		return NULL;
+	}
+
+	otg_ulpi_init(phy, otg, ops, flags);
+
+	return phy;
+}
+EXPORT_SYMBOL_GPL(devm_otg_ulpi_create);