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, 102 insertions, 0 deletions

diff --git a/drivers/net/phy/bcm63xx.c b/drivers/net/phy/bcm63xx.c
new file mode 100644
index 000000000..b46a736a3
--- /dev/null
+++ b/drivers/net/phy/bcm63xx.c
@@ -0,0 +1,102 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ *	Driver for Broadcom 63xx SOCs integrated PHYs
+ */
+#include "bcm-phy-lib.h"
+#include <linux/module.h>
+#include <linux/phy.h>
+
+#define MII_BCM63XX_IR		0x1a	/* interrupt register */
+#define MII_BCM63XX_IR_EN	0x4000	/* global interrupt enable */
+#define MII_BCM63XX_IR_DUPLEX	0x0800	/* duplex changed */
+#define MII_BCM63XX_IR_SPEED	0x0400	/* speed changed */
+#define MII_BCM63XX_IR_LINK	0x0200	/* link changed */
+#define MII_BCM63XX_IR_GMASK	0x0100	/* global interrupt mask */
+
+MODULE_DESCRIPTION("Broadcom 63xx internal PHY driver");
+MODULE_AUTHOR("Maxime Bizon <mbizon@freebox.fr>");
+MODULE_LICENSE("GPL");
+
+static int bcm63xx_config_intr(struct phy_device *phydev)
+{
+	int reg, err;
+
+	reg = phy_read(phydev, MII_BCM63XX_IR);
+	if (reg < 0)
+		return reg;
+
+	if (phydev->interrupts == PHY_INTERRUPT_ENABLED) {
+		err = bcm_phy_ack_intr(phydev);
+		if (err)
+			return err;
+
+		reg &= ~MII_BCM63XX_IR_GMASK;
+		err = phy_write(phydev, MII_BCM63XX_IR, reg);
+	} else {
+		reg |= MII_BCM63XX_IR_GMASK;
+		err = phy_write(phydev, MII_BCM63XX_IR, reg);
+		if (err)
+			return err;
+
+		err = bcm_phy_ack_intr(phydev);
+	}
+
+	return err;
+}
+
+static int bcm63xx_config_init(struct phy_device *phydev)
+{
+	int reg, err;
+
+	/* ASYM_PAUSE bit is marked RO in datasheet, so don't cheat */
+	linkmode_set_bit(ETHTOOL_LINK_MODE_Pause_BIT, phydev->supported);
+
+	reg = phy_read(phydev, MII_BCM63XX_IR);
+	if (reg < 0)
+		return reg;
+
+	/* Mask interrupts globally.  */
+	reg |= MII_BCM63XX_IR_GMASK;
+	err = phy_write(phydev, MII_BCM63XX_IR, reg);
+	if (err < 0)
+		return err;
+
+	/* Unmask events we are interested in  */
+	reg = ~(MII_BCM63XX_IR_DUPLEX |
+		MII_BCM63XX_IR_SPEED |
+		MII_BCM63XX_IR_LINK) |
+		MII_BCM63XX_IR_EN;
+	return phy_write(phydev, MII_BCM63XX_IR, reg);
+}
+
+static struct phy_driver bcm63xx_driver[] = {
+{
+	.phy_id		= 0x00406000,
+	.phy_id_mask	= 0xfffffc00,
+	.name		= "Broadcom BCM63XX (1)",
+	/* PHY_BASIC_FEATURES */
+	.flags		= PHY_IS_INTERNAL,
+	.config_init	= bcm63xx_config_init,
+	.config_intr	= bcm63xx_config_intr,
+	.handle_interrupt = bcm_phy_handle_interrupt,
+}, {
+	/* same phy as above, with just a different OUI */
+	.phy_id		= 0x002bdc00,
+	.phy_id_mask	= 0xfffffc00,
+	.name		= "Broadcom BCM63XX (2)",
+	/* PHY_BASIC_FEATURES */
+	.flags		= PHY_IS_INTERNAL,
+	.config_init	= bcm63xx_config_init,
+	.config_intr	= bcm63xx_config_intr,
+	.handle_interrupt = bcm_phy_handle_interrupt,
+} };
+
+module_phy_driver(bcm63xx_driver);
+
+static const struct mdio_device_id __maybe_unused bcm63xx_tbl[] = {
+	{ 0x00406000, 0xfffffc00 },
+	{ 0x002bdc00, 0xfffffc00 },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(mdio, bcm63xx_tbl);