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, 220 insertions, 0 deletions

diff --git a/drivers/net/phy/davicom.c b/drivers/net/phy/davicom.c
new file mode 100644
index 000000000..fa3692508
--- /dev/null
+++ b/drivers/net/phy/davicom.c
@@ -0,0 +1,220 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * drivers/net/phy/davicom.c
+ *
+ * Driver for Davicom 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>
+
+#define MII_DM9161_SCR		0x10
+#define MII_DM9161_SCR_INIT	0x0610
+#define MII_DM9161_SCR_RMII	0x0100
+
+/* DM9161 Interrupt Register */
+#define MII_DM9161_INTR	0x15
+#define MII_DM9161_INTR_PEND		0x8000
+#define MII_DM9161_INTR_DPLX_MASK	0x0800
+#define MII_DM9161_INTR_SPD_MASK	0x0400
+#define MII_DM9161_INTR_LINK_MASK	0x0200
+#define MII_DM9161_INTR_MASK		0x0100
+#define MII_DM9161_INTR_DPLX_CHANGE	0x0010
+#define MII_DM9161_INTR_SPD_CHANGE	0x0008
+#define MII_DM9161_INTR_LINK_CHANGE	0x0004
+#define MII_DM9161_INTR_INIT		0x0000
+#define MII_DM9161_INTR_STOP	\
+	(MII_DM9161_INTR_DPLX_MASK | MII_DM9161_INTR_SPD_MASK |	\
+	 MII_DM9161_INTR_LINK_MASK | MII_DM9161_INTR_MASK)
+#define MII_DM9161_INTR_CHANGE	\
+	(MII_DM9161_INTR_DPLX_CHANGE | \
+	 MII_DM9161_INTR_SPD_CHANGE | \
+	 MII_DM9161_INTR_LINK_CHANGE)
+
+/* DM9161 10BT Configuration/Status */
+#define MII_DM9161_10BTCSR	0x12
+#define MII_DM9161_10BTCSR_INIT	0x7800
+
+MODULE_DESCRIPTION("Davicom PHY driver");
+MODULE_AUTHOR("Andy Fleming");
+MODULE_LICENSE("GPL");
+
+
+static int dm9161_ack_interrupt(struct phy_device *phydev)
+{
+	int err = phy_read(phydev, MII_DM9161_INTR);
+
+	return (err < 0) ? err : 0;
+}
+
+#define DM9161_DELAY 1
+static int dm9161_config_intr(struct phy_device *phydev)
+{
+	int temp, err;
+
+	temp = phy_read(phydev, MII_DM9161_INTR);
+
+	if (temp < 0)
+		return temp;
+
+	if (phydev->interrupts == PHY_INTERRUPT_ENABLED) {
+		err = dm9161_ack_interrupt(phydev);
+		if (err)
+			return err;
+
+		temp &= ~(MII_DM9161_INTR_STOP);
+		err = phy_write(phydev, MII_DM9161_INTR, temp);
+	} else {
+		temp |= MII_DM9161_INTR_STOP;
+		err = phy_write(phydev, MII_DM9161_INTR, temp);
+		if (err)
+			return err;
+
+		err = dm9161_ack_interrupt(phydev);
+	}
+
+	return err;
+}
+
+static irqreturn_t dm9161_handle_interrupt(struct phy_device *phydev)
+{
+	int irq_status;
+
+	irq_status = phy_read(phydev, MII_DM9161_INTR);
+	if (irq_status < 0) {
+		phy_error(phydev);
+		return IRQ_NONE;
+	}
+
+	if (!(irq_status & MII_DM9161_INTR_CHANGE))
+		return IRQ_NONE;
+
+	phy_trigger_machine(phydev);
+
+	return IRQ_HANDLED;
+}
+
+static int dm9161_config_aneg(struct phy_device *phydev)
+{
+	int err;
+
+	/* Isolate the PHY */
+	err = phy_write(phydev, MII_BMCR, BMCR_ISOLATE);
+
+	if (err < 0)
+		return err;
+
+	/* Configure the new settings */
+	err = genphy_config_aneg(phydev);
+
+	if (err < 0)
+		return err;
+
+	return 0;
+}
+
+static int dm9161_config_init(struct phy_device *phydev)
+{
+	int err, temp;
+
+	/* Isolate the PHY */
+	err = phy_write(phydev, MII_BMCR, BMCR_ISOLATE);
+
+	if (err < 0)
+		return err;
+
+	switch (phydev->interface) {
+	case PHY_INTERFACE_MODE_MII:
+		temp = MII_DM9161_SCR_INIT;
+		break;
+	case PHY_INTERFACE_MODE_RMII:
+		temp =  MII_DM9161_SCR_INIT | MII_DM9161_SCR_RMII;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	/* Do not bypass the scrambler/descrambler */
+	err = phy_write(phydev, MII_DM9161_SCR, temp);
+	if (err < 0)
+		return err;
+
+	/* Clear 10BTCSR to default */
+	err = phy_write(phydev, MII_DM9161_10BTCSR, MII_DM9161_10BTCSR_INIT);
+
+	if (err < 0)
+		return err;
+
+	/* Reconnect the PHY, and enable Autonegotiation */
+	return phy_write(phydev, MII_BMCR, BMCR_ANENABLE);
+}
+
+static struct phy_driver dm91xx_driver[] = {
+{
+	.phy_id		= 0x0181b880,
+	.name		= "Davicom DM9161E",
+	.phy_id_mask	= 0x0ffffff0,
+	/* PHY_BASIC_FEATURES */
+	.config_init	= dm9161_config_init,
+	.config_aneg	= dm9161_config_aneg,
+	.config_intr	= dm9161_config_intr,
+	.handle_interrupt = dm9161_handle_interrupt,
+}, {
+	.phy_id		= 0x0181b8b0,
+	.name		= "Davicom DM9161B/C",
+	.phy_id_mask	= 0x0ffffff0,
+	/* PHY_BASIC_FEATURES */
+	.config_init	= dm9161_config_init,
+	.config_aneg	= dm9161_config_aneg,
+	.config_intr	= dm9161_config_intr,
+	.handle_interrupt = dm9161_handle_interrupt,
+}, {
+	.phy_id		= 0x0181b8a0,
+	.name		= "Davicom DM9161A",
+	.phy_id_mask	= 0x0ffffff0,
+	/* PHY_BASIC_FEATURES */
+	.config_init	= dm9161_config_init,
+	.config_aneg	= dm9161_config_aneg,
+	.config_intr	= dm9161_config_intr,
+	.handle_interrupt = dm9161_handle_interrupt,
+}, {
+	.phy_id		= 0x00181b80,
+	.name		= "Davicom DM9131",
+	.phy_id_mask	= 0x0ffffff0,
+	/* PHY_BASIC_FEATURES */
+	.config_intr	= dm9161_config_intr,
+	.handle_interrupt = dm9161_handle_interrupt,
+} };
+
+module_phy_driver(dm91xx_driver);
+
+static const struct mdio_device_id __maybe_unused davicom_tbl[] = {
+	{ 0x0181b880, 0x0ffffff0 },
+	{ 0x0181b8b0, 0x0ffffff0 },
+	{ 0x0181b8a0, 0x0ffffff0 },
+	{ 0x00181b80, 0x0ffffff0 },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(mdio, davicom_tbl);