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, 112 insertions, 0 deletions

diff --git a/include/uapi/rdma/mthca-abi.h b/include/uapi/rdma/mthca-abi.h
new file mode 100644
index 000000000..91b12e1a6
--- /dev/null
+++ b/include/uapi/rdma/mthca-abi.h
@@ -0,0 +1,112 @@
+/* SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR Linux-OpenIB) */
+/*
+ * Copyright (c) 2005 Topspin Communications.  All rights reserved.
+ * Copyright (c) 2005, 2006 Cisco Systems.  All rights reserved.
+ *
+ * This software is available to you under a choice of one of two
+ * licenses.  You may choose to be licensed under the terms of the GNU
+ * General Public License (GPL) Version 2, available from the file
+ * COPYING in the main directory of this source tree, or the
+ * OpenIB.org BSD license below:
+ *
+ *     Redistribution and use in source and binary forms, with or
+ *     without modification, are permitted provided that the following
+ *     conditions are met:
+ *
+ *      - Redistributions of source code must retain the above
+ *        copyright notice, this list of conditions and the following
+ *        disclaimer.
+ *
+ *      - Redistributions in binary form must reproduce the above
+ *        copyright notice, this list of conditions and the following
+ *        disclaimer in the documentation and/or other materials
+ *        provided with the distribution.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef MTHCA_ABI_USER_H
+#define MTHCA_ABI_USER_H
+
+#include <linux/types.h>
+
+/*
+ * Increment this value if any changes that break userspace ABI
+ * compatibility are made.
+ */
+#define MTHCA_UVERBS_ABI_VERSION	1
+
+/*
+ * Make sure that all structs defined in this file remain laid out so
+ * that they pack the same way on 32-bit and 64-bit architectures (to
+ * avoid incompatibility between 32-bit userspace and 64-bit kernels).
+ * In particular do not use pointer types -- pass pointers in __u64
+ * instead.
+ */
+struct mthca_alloc_ucontext_resp {
+	__u32 qp_tab_size;
+	__u32 uarc_size;
+};
+
+struct mthca_alloc_pd_resp {
+	__u32 pdn;
+	__u32 reserved;
+};
+
+/*
+ * Mark the memory region with a DMA attribute that causes
+ * in-flight DMA to be flushed when the region is written to:
+ */
+#define MTHCA_MR_DMASYNC	0x1
+
+struct mthca_reg_mr {
+	__u32 mr_attrs;
+	__u32 reserved;
+};
+
+struct mthca_create_cq {
+	__u32 lkey;
+	__u32 pdn;
+	__aligned_u64 arm_db_page;
+	__aligned_u64 set_db_page;
+	__u32 arm_db_index;
+	__u32 set_db_index;
+};
+
+struct mthca_create_cq_resp {
+	__u32 cqn;
+	__u32 reserved;
+};
+
+struct mthca_resize_cq {
+	__u32 lkey;
+	__u32 reserved;
+};
+
+struct mthca_create_srq {
+	__u32 lkey;
+	__u32 db_index;
+	__aligned_u64 db_page;
+};
+
+struct mthca_create_srq_resp {
+	__u32 srqn;
+	__u32 reserved;
+};
+
+struct mthca_create_qp {
+	__u32 lkey;
+	__u32 reserved;
+	__aligned_u64 sq_db_page;
+	__aligned_u64 rq_db_page;
+	__u32 sq_db_index;
+	__u32 rq_db_index;
+};
+#endif /* MTHCA_ABI_USER_H */