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, 96 insertions, 0 deletions

diff --git a/drivers/net/phy/teranetics.c b/drivers/net/phy/teranetics.c
new file mode 100644
index 000000000..46c5ff7d7
--- /dev/null
+++ b/drivers/net/phy/teranetics.c
@@ -0,0 +1,96 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Driver for Teranetics PHY
+ *
+ * Author: Shaohui Xie <Shaohui.Xie@freescale.com>
+ *
+ * Copyright 2015 Freescale Semiconductor, Inc.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mii.h>
+#include <linux/ethtool.h>
+#include <linux/mdio.h>
+#include <linux/phy.h>
+
+MODULE_DESCRIPTION("Teranetics PHY driver");
+MODULE_AUTHOR("Shaohui Xie <Shaohui.Xie@freescale.com>");
+MODULE_LICENSE("GPL v2");
+
+#define PHY_ID_TN2020	0x00a19410
+#define MDIO_PHYXS_LNSTAT_SYNC0	0x0001
+#define MDIO_PHYXS_LNSTAT_SYNC1	0x0002
+#define MDIO_PHYXS_LNSTAT_SYNC2	0x0004
+#define MDIO_PHYXS_LNSTAT_SYNC3	0x0008
+#define MDIO_PHYXS_LNSTAT_ALIGN 0x1000
+
+#define MDIO_PHYXS_LANE_READY	(MDIO_PHYXS_LNSTAT_SYNC0 | \
+				MDIO_PHYXS_LNSTAT_SYNC1 | \
+				MDIO_PHYXS_LNSTAT_SYNC2 | \
+				MDIO_PHYXS_LNSTAT_SYNC3 | \
+				MDIO_PHYXS_LNSTAT_ALIGN)
+
+static int teranetics_aneg_done(struct phy_device *phydev)
+{
+	/* auto negotiation state can only be checked when using copper
+	 * port, if using fiber port, just lie it's done.
+	 */
+	if (!phy_read_mmd(phydev, MDIO_MMD_VEND1, 93))
+		return genphy_c45_aneg_done(phydev);
+
+	return 1;
+}
+
+static int teranetics_read_status(struct phy_device *phydev)
+{
+	int reg;
+
+	phydev->link = 1;
+
+	phydev->speed = SPEED_10000;
+	phydev->duplex = DUPLEX_FULL;
+
+	if (!phy_read_mmd(phydev, MDIO_MMD_VEND1, 93)) {
+		reg = phy_read_mmd(phydev, MDIO_MMD_PHYXS, MDIO_PHYXS_LNSTAT);
+		if (reg < 0 ||
+		    !((reg & MDIO_PHYXS_LANE_READY) == MDIO_PHYXS_LANE_READY)) {
+			phydev->link = 0;
+			return 0;
+		}
+
+		reg = phy_read_mmd(phydev, MDIO_MMD_AN, MDIO_STAT1);
+		if (reg < 0 || !(reg & MDIO_STAT1_LSTATUS))
+			phydev->link = 0;
+	}
+
+	return 0;
+}
+
+static int teranetics_match_phy_device(struct phy_device *phydev,
+				       const struct phy_driver *phydrv)
+{
+	return phydev->c45_ids.device_ids[3] == PHY_ID_TN2020;
+}
+
+static struct phy_driver teranetics_driver[] = {
+{
+	.phy_id		= PHY_ID_TN2020,
+	.phy_id_mask	= 0xffffffff,
+	.name		= "Teranetics TN2020",
+	.features       = PHY_10GBIT_FEATURES,
+	.aneg_done	= teranetics_aneg_done,
+	.config_aneg    = gen10g_config_aneg,
+	.read_status	= teranetics_read_status,
+	.match_phy_device = teranetics_match_phy_device,
+},
+};
+
+module_phy_driver(teranetics_driver);
+
+static const struct mdio_device_id __maybe_unused teranetics_tbl[] = {
+	{ PHY_ID_TN2020, 0xffffffff },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(mdio, teranetics_tbl);