x86/amd_node: Fix PCI device reference counting in amd_smn_init()grafted

The local "root" pointer is a temporary variable used during the device
search. Therefore, refcount related to the search iterators should be cleaned
up after the search is complete.

Use the __free() cleanup macro to ensure the refcount is decremented when the
temporary pointer goes out of scope.

Additionally, increment the refcount when caching a root pointer. This ensures
the in-use refcount is separate from the temporary search refcounting.

Finally, drop the redundant "root = NULL" before the second search loop. The
pci_get_class() iterator always decrements the refcount of its "from"
argument, so the first loop can only fall through with "root" already NULL.

Fixes: 0a4b61d9c2e4 ("x86/amd_node: Fix AMD root device caching")
Closes: https://sashiko.dev/#/patchset/20260806160159.230453-1-jason.andryuk%40amd.com
Reported-by: Sashiko <sashiko-bot@kernel.org>
Assisted-by: LLM
Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Cc: <stable@kernel.org>
Link: https://patch.msgid.link/20260903154325.74343-1-yazen.ghannam@amd.com

1 files changed, 137 insertions, 0 deletions

diff --git a/drivers/net/phy/ste10Xp.c b/drivers/net/phy/ste10Xp.c
new file mode 100644
index 000000000..d4835d4c5
--- /dev/null
+++ b/drivers/net/phy/ste10Xp.c
@@ -0,0 +1,137 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * drivers/net/phy/ste10Xp.c
+ *
+ * Driver for STMicroelectronics STe10Xp PHYs
+ *
+ * Author: Giuseppe Cavallaro <peppe.cavallaro@st.com>
+ *
+ * Copyright (c) 2008 STMicroelectronics Limited
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/moduleparam.h>
+#include <linux/interrupt.h>
+#include <linux/netdevice.h>
+#include <linux/ethtool.h>
+#include <linux/mii.h>
+#include <linux/phy.h>
+
+#define MII_XCIIS	0x11	/* Configuration Info IRQ & Status Reg */
+#define MII_XIE		0x12	/* Interrupt Enable Register */
+#define MII_XIE_DEFAULT_MASK 0x0070 /* ANE complete, Remote Fault, Link Down */
+
+#define STE101P_PHY_ID		0x00061c50
+#define STE100P_PHY_ID		0x1c040011
+
+static int ste10Xp_config_init(struct phy_device *phydev)
+{
+	int value, err;
+
+	/* Software Reset PHY */
+	value = phy_read(phydev, MII_BMCR);
+	if (value < 0)
+		return value;
+
+	value |= BMCR_RESET;
+	err = phy_write(phydev, MII_BMCR, value);
+	if (err < 0)
+		return err;
+
+	do {
+		value = phy_read(phydev, MII_BMCR);
+	} while (value & BMCR_RESET);
+
+	return 0;
+}
+
+static int ste10Xp_ack_interrupt(struct phy_device *phydev)
+{
+	int err = phy_read(phydev, MII_XCIIS);
+
+	if (err < 0)
+		return err;
+
+	return 0;
+}
+
+static int ste10Xp_config_intr(struct phy_device *phydev)
+{
+	int err;
+
+	if (phydev->interrupts == PHY_INTERRUPT_ENABLED) {
+		/* clear any pending interrupts */
+		err = ste10Xp_ack_interrupt(phydev);
+		if (err)
+			return err;
+
+		/* Enable all STe101P interrupts (PR12) */
+		err = phy_write(phydev, MII_XIE, MII_XIE_DEFAULT_MASK);
+	} else {
+		err = phy_write(phydev, MII_XIE, 0);
+		if (err)
+			return err;
+
+		err = ste10Xp_ack_interrupt(phydev);
+	}
+
+	return err;
+}
+
+static irqreturn_t ste10Xp_handle_interrupt(struct phy_device *phydev)
+{
+	int irq_status;
+
+	irq_status = phy_read(phydev, MII_XCIIS);
+	if (irq_status < 0) {
+		phy_error(phydev);
+		return IRQ_NONE;
+	}
+
+	if (!(irq_status & MII_XIE_DEFAULT_MASK))
+		return IRQ_NONE;
+
+	phy_trigger_machine(phydev);
+
+	return IRQ_HANDLED;
+}
+
+static struct phy_driver ste10xp_pdriver[] = {
+{
+	.phy_id = STE101P_PHY_ID,
+	.phy_id_mask = 0xfffffff0,
+	.name = "STe101p",
+	/* PHY_BASIC_FEATURES */
+	.config_init = ste10Xp_config_init,
+	.config_intr = ste10Xp_config_intr,
+	.handle_interrupt = ste10Xp_handle_interrupt,
+	.suspend = genphy_suspend,
+	.resume = genphy_resume,
+}, {
+	.phy_id = STE100P_PHY_ID,
+	.phy_id_mask = 0xffffffff,
+	.name = "STe100p",
+	/* PHY_BASIC_FEATURES */
+	.config_init = ste10Xp_config_init,
+	.config_intr = ste10Xp_config_intr,
+	.handle_interrupt = ste10Xp_handle_interrupt,
+	.suspend = genphy_suspend,
+	.resume = genphy_resume,
+} };
+
+module_phy_driver(ste10xp_pdriver);
+
+static const struct mdio_device_id __maybe_unused ste10Xp_tbl[] = {
+	{ STE101P_PHY_ID, 0xfffffff0 },
+	{ STE100P_PHY_ID, 0xffffffff },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(mdio, ste10Xp_tbl);
+
+MODULE_DESCRIPTION("STMicroelectronics STe10Xp PHY driver");
+MODULE_AUTHOR("Giuseppe Cavallaro <peppe.cavallaro@st.com>");
+MODULE_LICENSE("GPL");