ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 358 insertions, 0 deletions

diff --git a/drivers/net/phy/lxt.c b/drivers/net/phy/lxt.c
new file mode 100644
index 000000000..5251a61c8
--- /dev/null
+++ b/drivers/net/phy/lxt.c
@@ -0,0 +1,358 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * drivers/net/phy/lxt.c
+ *
+ * Driver for Intel LXT PHYs
+ *
+ * Author: Andy Fleming
+ *
+ * Copyright (c) 2004 Freescale Semiconductor, Inc.
+ */
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/errno.h>
+#include <linux/unistd.h>
+#include <linux/interrupt.h>
+#include <linux/init.h>
+#include <linux/delay.h>
+#include <linux/netdevice.h>
+#include <linux/etherdevice.h>
+#include <linux/skbuff.h>
+#include <linux/spinlock.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/mii.h>
+#include <linux/ethtool.h>
+#include <linux/phy.h>
+
+#include <asm/io.h>
+#include <asm/irq.h>
+#include <linux/uaccess.h>
+
+/* The Level one LXT970 is used by many boards				     */
+
+#define MII_LXT970_IER       17  /* Interrupt Enable Register */
+
+#define MII_LXT970_IER_IEN	0x0002
+
+#define MII_LXT970_ISR       18  /* Interrupt Status Register */
+
+#define MII_LXT970_IRS_MINT  BIT(15)
+
+#define MII_LXT970_CONFIG    19  /* Configuration Register    */
+
+/* ------------------------------------------------------------------------- */
+/* The Level one LXT971 is used on some of my custom boards                  */
+
+/* register definitions for the 971 */
+#define MII_LXT971_IER		18  /* Interrupt Enable Register */
+#define MII_LXT971_IER_IEN	0x00f2
+
+#define MII_LXT971_ISR		19  /* Interrupt Status Register */
+#define MII_LXT971_ISR_MASK	0x00f0
+
+/* register definitions for the 973 */
+#define MII_LXT973_PCR 16 /* Port Configuration Register */
+#define PCR_FIBER_SELECT 1
+
+MODULE_DESCRIPTION("Intel LXT PHY driver");
+MODULE_AUTHOR("Andy Fleming");
+MODULE_LICENSE("GPL");
+
+static int lxt970_ack_interrupt(struct phy_device *phydev)
+{
+	int err;
+
+	err = phy_read(phydev, MII_BMSR);
+
+	if (err < 0)
+		return err;
+
+	err = phy_read(phydev, MII_LXT970_ISR);
+
+	if (err < 0)
+		return err;
+
+	return 0;
+}
+
+static int lxt970_config_intr(struct phy_device *phydev)
+{
+	int err;
+
+	if (phydev->interrupts == PHY_INTERRUPT_ENABLED) {
+		err = lxt970_ack_interrupt(phydev);
+		if (err)
+			return err;
+
+		err = phy_write(phydev, MII_LXT970_IER, MII_LXT970_IER_IEN);
+	} else {
+		err = phy_write(phydev, MII_LXT970_IER, 0);
+		if (err)
+			return err;
+
+		err = lxt970_ack_interrupt(phydev);
+	}
+
+	return err;
+}
+
+static irqreturn_t lxt970_handle_interrupt(struct phy_device *phydev)
+{
+	int irq_status;
+
+	/* The interrupt status register is cleared by reading BMSR
+	 * followed by MII_LXT970_ISR
+	 */
+	irq_status = phy_read(phydev, MII_BMSR);
+	if (irq_status < 0) {
+		phy_error(phydev);
+		return IRQ_NONE;
+	}
+
+	irq_status = phy_read(phydev, MII_LXT970_ISR);
+	if (irq_status < 0) {
+		phy_error(phydev);
+		return IRQ_NONE;
+	}
+
+	if (!(irq_status & MII_LXT970_IRS_MINT))
+		return IRQ_NONE;
+
+	phy_trigger_machine(phydev);
+
+	return IRQ_HANDLED;
+}
+
+static int lxt970_config_init(struct phy_device *phydev)
+{
+	return phy_write(phydev, MII_LXT970_CONFIG, 0);
+}
+
+
+static int lxt971_ack_interrupt(struct phy_device *phydev)
+{
+	int err = phy_read(phydev, MII_LXT971_ISR);
+
+	if (err < 0)
+		return err;
+
+	return 0;
+}
+
+static int lxt971_config_intr(struct phy_device *phydev)
+{
+	int err;
+
+	if (phydev->interrupts == PHY_INTERRUPT_ENABLED) {
+		err = lxt971_ack_interrupt(phydev);
+		if (err)
+			return err;
+
+		err = phy_write(phydev, MII_LXT971_IER, MII_LXT971_IER_IEN);
+	} else {
+		err = phy_write(phydev, MII_LXT971_IER, 0);
+		if (err)
+			return err;
+
+		err = lxt971_ack_interrupt(phydev);
+	}
+
+	return err;
+}
+
+static irqreturn_t lxt971_handle_interrupt(struct phy_device *phydev)
+{
+	int irq_status;
+
+	irq_status = phy_read(phydev, MII_LXT971_ISR);
+	if (irq_status < 0) {
+		phy_error(phydev);
+		return IRQ_NONE;
+	}
+
+	if (!(irq_status & MII_LXT971_ISR_MASK))
+		return IRQ_NONE;
+
+	phy_trigger_machine(phydev);
+
+	return IRQ_HANDLED;
+}
+
+/*
+ * A2 version of LXT973 chip has an ERRATA: it randomly return the contents
+ * of the previous even register when you read a odd register regularly
+ */
+
+static int lxt973a2_update_link(struct phy_device *phydev)
+{
+	int status;
+	int control;
+	int retry = 8; /* we try 8 times */
+
+	/* Do a fake read */
+	status = phy_read(phydev, MII_BMSR);
+
+	if (status < 0)
+		return status;
+
+	control = phy_read(phydev, MII_BMCR);
+	if (control < 0)
+		return control;
+
+	do {
+		/* Read link and autonegotiation status */
+		status = phy_read(phydev, MII_BMSR);
+	} while (status >= 0 && retry-- && status == control);
+
+	if (status < 0)
+		return status;
+
+	if ((status & BMSR_LSTATUS) == 0)
+		phydev->link = 0;
+	else
+		phydev->link = 1;
+
+	return 0;
+}
+
+static int lxt973a2_read_status(struct phy_device *phydev)
+{
+	int adv;
+	int err;
+	int lpa;
+
+	/* Update the link, but return if there was an error */
+	err = lxt973a2_update_link(phydev);
+	if (err)
+		return err;
+
+	if (AUTONEG_ENABLE == phydev->autoneg) {
+		int retry = 1;
+
+		adv = phy_read(phydev, MII_ADVERTISE);
+
+		if (adv < 0)
+			return adv;
+
+		do {
+			lpa = phy_read(phydev, MII_LPA);
+
+			if (lpa < 0)
+				return lpa;
+
+			/* If both registers are equal, it is suspect but not
+			 * impossible, hence a new try
+			 */
+		} while (lpa == adv && retry--);
+
+		mii_lpa_to_linkmode_lpa_t(phydev->lp_advertising, lpa);
+
+		lpa &= adv;
+
+		phydev->speed = SPEED_10;
+		phydev->duplex = DUPLEX_HALF;
+		phydev->pause = phydev->asym_pause = 0;
+
+		if (lpa & (LPA_100FULL | LPA_100HALF)) {
+			phydev->speed = SPEED_100;
+
+			if (lpa & LPA_100FULL)
+				phydev->duplex = DUPLEX_FULL;
+		} else {
+			if (lpa & LPA_10FULL)
+				phydev->duplex = DUPLEX_FULL;
+		}
+
+		phy_resolve_aneg_pause(phydev);
+	} else {
+		err = genphy_read_status_fixed(phydev);
+		if (err < 0)
+			return err;
+
+		phydev->pause = phydev->asym_pause = 0;
+		linkmode_zero(phydev->lp_advertising);
+	}
+
+	return 0;
+}
+
+static int lxt973_probe(struct phy_device *phydev)
+{
+	int val = phy_read(phydev, MII_LXT973_PCR);
+
+	if (val & PCR_FIBER_SELECT) {
+		/*
+		 * If fiber is selected, then the only correct setting
+		 * is 100Mbps, full duplex, and auto negotiation off.
+		 */
+		val = phy_read(phydev, MII_BMCR);
+		val |= (BMCR_SPEED100 | BMCR_FULLDPLX);
+		val &= ~BMCR_ANENABLE;
+		phy_write(phydev, MII_BMCR, val);
+		/* Remember that the port is in fiber mode. */
+		phydev->priv = lxt973_probe;
+		phydev->port = PORT_FIBRE;
+	} else {
+		phydev->priv = NULL;
+	}
+	return 0;
+}
+
+static int lxt973_config_aneg(struct phy_device *phydev)
+{
+	/* Do nothing if port is in fiber mode. */
+	return phydev->priv ? 0 : genphy_config_aneg(phydev);
+}
+
+static struct phy_driver lxt97x_driver[] = {
+{
+	.phy_id		= 0x78100000,
+	.name		= "LXT970",
+	.phy_id_mask	= 0xfffffff0,
+	/* PHY_BASIC_FEATURES */
+	.config_init	= lxt970_config_init,
+	.config_intr	= lxt970_config_intr,
+	.handle_interrupt = lxt970_handle_interrupt,
+}, {
+	.phy_id		= 0x001378e0,
+	.name		= "LXT971",
+	.phy_id_mask	= 0xfffffff0,
+	/* PHY_BASIC_FEATURES */
+	.config_intr	= lxt971_config_intr,
+	.handle_interrupt = lxt971_handle_interrupt,
+	.suspend	= genphy_suspend,
+	.resume		= genphy_resume,
+}, {
+	.phy_id		= 0x00137a10,
+	.name		= "LXT973-A2",
+	.phy_id_mask	= 0xffffffff,
+	/* PHY_BASIC_FEATURES */
+	.flags		= 0,
+	.probe		= lxt973_probe,
+	.config_aneg	= lxt973_config_aneg,
+	.read_status	= lxt973a2_read_status,
+	.suspend	= genphy_suspend,
+	.resume		= genphy_resume,
+}, {
+	.phy_id		= 0x00137a10,
+	.name		= "LXT973",
+	.phy_id_mask	= 0xfffffff0,
+	/* PHY_BASIC_FEATURES */
+	.flags		= 0,
+	.probe		= lxt973_probe,
+	.config_aneg	= lxt973_config_aneg,
+	.suspend	= genphy_suspend,
+	.resume		= genphy_resume,
+} };
+
+module_phy_driver(lxt97x_driver);
+
+static const struct mdio_device_id __maybe_unused lxt_tbl[] = {
+	{ 0x78100000, 0xfffffff0 },
+	{ 0x001378e0, 0xfffffff0 },
+	{ 0x00137a10, 0xfffffff0 },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(mdio, lxt_tbl);