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, 53 insertions, 0 deletions

diff --git a/drivers/nfc/mei_phy.h b/drivers/nfc/mei_phy.h
new file mode 100644
index 000000000..9b9c5eb54
--- /dev/null
+++ b/drivers/nfc/mei_phy.h
@@ -0,0 +1,53 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __LOCAL_MEI_PHY_H_
+#define __LOCAL_MEI_PHY_H_
+
+#include <linux/mei_cl_bus.h>
+#include <net/nfc/hci.h>
+#include <linux/uuid.h>
+
+#define MEI_NFC_UUID UUID_LE(0x0bb17a78, 0x2a8e, 0x4c50, \
+		0x94, 0xd4, 0x50, 0x26, 0x67, 0x23, 0x77, 0x5c)
+#define MEI_NFC_HEADER_SIZE 10
+#define MEI_NFC_MAX_HCI_PAYLOAD 300
+
+/**
+ * struct nfc_mei_phy - NFC description of the MEI PHY and interface functions
+ *
+ * @cldev: mei client device
+ * @hdev:   nfc hci device
+ *
+ * @send_wq: send completion wait queue
+ * @fw_ivn: NFC Interface Version Number
+ * @vendor_id: NFC manufacturer ID
+ * @radio_type: NFC radio type
+ * @reserved: reserved for alignment
+ * @req_id:  message counter
+ * @recv_req_id: reception message counter
+ * @powered: the device is in powered state
+ * @hard_fault: < 0 if hardware error occurred
+ *    and prevents normal operation.
+ */
+struct nfc_mei_phy {
+	struct mei_cl_device *cldev;
+	struct nfc_hci_dev *hdev;
+
+	wait_queue_head_t send_wq;
+	u8 fw_ivn;
+	u8 vendor_id;
+	u8 radio_type;
+	u8 reserved;
+
+	u16 req_id;
+	u16 recv_req_id;
+
+	int powered;
+	int hard_fault;
+};
+
+extern const struct nfc_phy_ops mei_phy_ops;
+
+struct nfc_mei_phy *nfc_mei_phy_alloc(struct mei_cl_device *device);
+void nfc_mei_phy_free(struct nfc_mei_phy *phy);
+
+#endif /* __LOCAL_MEI_PHY_H_ */