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, 98 insertions, 0 deletions

diff --git a/drivers/net/phy/uPD60620.c b/drivers/net/phy/uPD60620.c
new file mode 100644
index 000000000..900cb756c
--- /dev/null
+++ b/drivers/net/phy/uPD60620.c
@@ -0,0 +1,98 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Driver for the Renesas PHY uPD60620.
+ *
+ * Copyright (C) 2015 Softing Industrial Automation GmbH
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/phy.h>
+
+#define UPD60620_PHY_ID    0xb8242824
+
+/* Extended Registers and values */
+/* PHY Special Control/Status    */
+#define PHY_PHYSCR         0x1F      /* PHY.31 */
+#define PHY_PHYSCR_10MB    0x0004    /* PHY speed = 10mb */
+#define PHY_PHYSCR_100MB   0x0008    /* PHY speed = 100mb */
+#define PHY_PHYSCR_DUPLEX  0x0010    /* PHY Duplex */
+
+/* PHY Special Modes */
+#define PHY_SPM            0x12      /* PHY.18 */
+
+/* Init PHY */
+
+static int upd60620_config_init(struct phy_device *phydev)
+{
+	/* Enable support for passive HUBs (could be a strap option) */
+	/* PHYMODE: All speeds, HD in parallel detect */
+	return phy_write(phydev, PHY_SPM, 0x0180 | phydev->mdio.addr);
+}
+
+/* Get PHY status from common registers */
+
+static int upd60620_read_status(struct phy_device *phydev)
+{
+	int phy_state;
+
+	/* Read negotiated state */
+	phy_state = phy_read(phydev, MII_BMSR);
+	if (phy_state < 0)
+		return phy_state;
+
+	phydev->link = 0;
+	linkmode_zero(phydev->lp_advertising);
+	phydev->pause = 0;
+	phydev->asym_pause = 0;
+
+	if (phy_state & (BMSR_ANEGCOMPLETE | BMSR_LSTATUS)) {
+		phy_state = phy_read(phydev, PHY_PHYSCR);
+		if (phy_state < 0)
+			return phy_state;
+
+		if (phy_state & (PHY_PHYSCR_10MB | PHY_PHYSCR_100MB)) {
+			phydev->link = 1;
+			phydev->speed = SPEED_10;
+			phydev->duplex = DUPLEX_HALF;
+
+			if (phy_state & PHY_PHYSCR_100MB)
+				phydev->speed = SPEED_100;
+			if (phy_state & PHY_PHYSCR_DUPLEX)
+				phydev->duplex = DUPLEX_FULL;
+
+			phy_state = phy_read(phydev, MII_LPA);
+			if (phy_state < 0)
+				return phy_state;
+
+			mii_lpa_to_linkmode_lpa_t(phydev->lp_advertising,
+						  phy_state);
+
+			phy_resolve_aneg_pause(phydev);
+		}
+	}
+	return 0;
+}
+
+MODULE_DESCRIPTION("Renesas uPD60620 PHY driver");
+MODULE_AUTHOR("Bernd Edlinger <bernd.edlinger@hotmail.de>");
+MODULE_LICENSE("GPL");
+
+static struct phy_driver upd60620_driver[1] = { {
+	.phy_id         = UPD60620_PHY_ID,
+	.phy_id_mask    = 0xfffffffe,
+	.name           = "Renesas uPD60620",
+	/* PHY_BASIC_FEATURES */
+	.flags          = 0,
+	.config_init    = upd60620_config_init,
+	.read_status    = upd60620_read_status,
+} };
+
+module_phy_driver(upd60620_driver);
+
+static const struct mdio_device_id __maybe_unused upd60620_tbl[] = {
+	{ UPD60620_PHY_ID, 0xfffffffe },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(mdio, upd60620_tbl);