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, 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);