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, 124 insertions, 0 deletions

diff --git a/include/rdma/signature.h b/include/rdma/signature.h
new file mode 100644
index 000000000..d16b0fcc8
--- /dev/null
+++ b/include/rdma/signature.h
@@ -0,0 +1,124 @@
+/* SPDX-License-Identifier: (GPL-2.0 OR Linux-OpenIB) */
+/*
+ * Copyright (c) 2017-2018 Mellanox Technologies. All rights reserved.
+ */
+
+#ifndef _RDMA_SIGNATURE_H_
+#define _RDMA_SIGNATURE_H_
+
+#include <linux/types.h>
+
+enum ib_signature_prot_cap {
+	IB_PROT_T10DIF_TYPE_1 = 1,
+	IB_PROT_T10DIF_TYPE_2 = 1 << 1,
+	IB_PROT_T10DIF_TYPE_3 = 1 << 2,
+};
+
+enum ib_signature_guard_cap {
+	IB_GUARD_T10DIF_CRC	= 1,
+	IB_GUARD_T10DIF_CSUM	= 1 << 1,
+};
+
+/**
+ * enum ib_signature_type - Signature types
+ * @IB_SIG_TYPE_NONE: Unprotected.
+ * @IB_SIG_TYPE_T10_DIF: Type T10-DIF
+ */
+enum ib_signature_type {
+	IB_SIG_TYPE_NONE,
+	IB_SIG_TYPE_T10_DIF,
+};
+
+/**
+ * enum ib_t10_dif_bg_type - Signature T10-DIF block-guard types
+ * @IB_T10DIF_CRC: Corresponds to T10-PI mandated CRC checksum rules.
+ * @IB_T10DIF_CSUM: Corresponds to IP checksum rules.
+ */
+enum ib_t10_dif_bg_type {
+	IB_T10DIF_CRC,
+	IB_T10DIF_CSUM,
+};
+
+/**
+ * struct ib_t10_dif_domain - Parameters specific for T10-DIF
+ *     domain.
+ * @bg_type: T10-DIF block guard type (CRC|CSUM)
+ * @pi_interval: protection information interval.
+ * @bg: seed of guard computation.
+ * @app_tag: application tag of guard block
+ * @ref_tag: initial guard block reference tag.
+ * @ref_remap: Indicate wethear the reftag increments each block
+ * @app_escape: Indicate to skip block check if apptag=0xffff
+ * @ref_escape: Indicate to skip block check if reftag=0xffffffff
+ * @apptag_check_mask: check bitmask of application tag.
+ */
+struct ib_t10_dif_domain {
+	enum ib_t10_dif_bg_type bg_type;
+	u16			pi_interval;
+	u16			bg;
+	u16			app_tag;
+	u32			ref_tag;
+	bool			ref_remap;
+	bool			app_escape;
+	bool			ref_escape;
+	u16			apptag_check_mask;
+};
+
+/**
+ * struct ib_sig_domain - Parameters for signature domain
+ * @sig_type: specific signauture type
+ * @sig: union of all signature domain attributes that may
+ *     be used to set domain layout.
+ */
+struct ib_sig_domain {
+	enum ib_signature_type sig_type;
+	union {
+		struct ib_t10_dif_domain dif;
+	} sig;
+};
+
+/**
+ * struct ib_sig_attrs - Parameters for signature handover operation
+ * @check_mask: bitmask for signature byte check (8 bytes)
+ * @mem: memory domain layout descriptor.
+ * @wire: wire domain layout descriptor.
+ * @meta_length: metadata length
+ */
+struct ib_sig_attrs {
+	u8			check_mask;
+	struct ib_sig_domain	mem;
+	struct ib_sig_domain	wire;
+	int			meta_length;
+};
+
+enum ib_sig_err_type {
+	IB_SIG_BAD_GUARD,
+	IB_SIG_BAD_REFTAG,
+	IB_SIG_BAD_APPTAG,
+};
+
+/*
+ * Signature check masks (8 bytes in total) according to the T10-PI standard:
+ *  -------- -------- ------------
+ * | GUARD  | APPTAG |   REFTAG   |
+ * |  2B    |  2B    |    4B      |
+ *  -------- -------- ------------
+ */
+enum {
+	IB_SIG_CHECK_GUARD = 0xc0,
+	IB_SIG_CHECK_APPTAG = 0x30,
+	IB_SIG_CHECK_REFTAG = 0x0f,
+};
+
+/*
+ * struct ib_sig_err - signature error descriptor
+ */
+struct ib_sig_err {
+	enum ib_sig_err_type	err_type;
+	u32			expected;
+	u32			actual;
+	u64			sig_err_offset;
+	u32			key;
+};
+
+#endif /* _RDMA_SIGNATURE_H_ */