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, 187 insertions, 0 deletions

diff --git a/include/rdma/restrack.h b/include/rdma/restrack.h
new file mode 100644
index 000000000..47fec3083
--- /dev/null
+++ b/include/rdma/restrack.h
@@ -0,0 +1,187 @@
+/* SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB */
+/*
+ * Copyright (c) 2017-2018 Mellanox Technologies. All rights reserved.
+ */
+
+#ifndef _RDMA_RESTRACK_H_
+#define _RDMA_RESTRACK_H_
+
+#include <linux/typecheck.h>
+#include <linux/sched.h>
+#include <linux/kref.h>
+#include <linux/completion.h>
+#include <linux/sched/task.h>
+#include <uapi/rdma/rdma_netlink.h>
+#include <linux/xarray.h>
+
+/* Mark entry as containing driver specific details, it is used to provide QP subtype for now */
+#define RESTRACK_DD XA_MARK_1
+
+struct ib_device;
+struct sk_buff;
+
+/**
+ * enum rdma_restrack_type - HW objects to track
+ */
+enum rdma_restrack_type {
+	/**
+	 * @RDMA_RESTRACK_PD: Protection domain (PD)
+	 */
+	RDMA_RESTRACK_PD,
+	/**
+	 * @RDMA_RESTRACK_CQ: Completion queue (CQ)
+	 */
+	RDMA_RESTRACK_CQ,
+	/**
+	 * @RDMA_RESTRACK_QP: Queue pair (QP)
+	 */
+	RDMA_RESTRACK_QP,
+	/**
+	 * @RDMA_RESTRACK_CM_ID: Connection Manager ID (CM_ID)
+	 */
+	RDMA_RESTRACK_CM_ID,
+	/**
+	 * @RDMA_RESTRACK_MR: Memory Region (MR)
+	 */
+	RDMA_RESTRACK_MR,
+	/**
+	 * @RDMA_RESTRACK_CTX: Verbs contexts (CTX)
+	 */
+	RDMA_RESTRACK_CTX,
+	/**
+	 * @RDMA_RESTRACK_COUNTER: Statistic Counter
+	 */
+	RDMA_RESTRACK_COUNTER,
+	/**
+	 * @RDMA_RESTRACK_SRQ: Shared receive queue (SRQ)
+	 */
+	RDMA_RESTRACK_SRQ,
+	/**
+	 * @RDMA_RESTRACK_DMAH: DMA handle
+	 */
+	RDMA_RESTRACK_DMAH,
+	/**
+	 * @RDMA_RESTRACK_COMP_CNTR: Completion Counter
+	 */
+	RDMA_RESTRACK_COMP_CNTR,
+	/**
+	 * @RDMA_RESTRACK_MAX: Last entry, used for array dclarations
+	 */
+	RDMA_RESTRACK_MAX
+};
+
+/**
+ * struct rdma_restrack_entry - metadata per-entry
+ */
+struct rdma_restrack_entry {
+	/**
+	 * @valid: validity indicator
+	 *
+	 * The entries are filled during rdma_restrack_add,
+	 * can be attempted to be free during rdma_restrack_del.
+	 *
+	 * As an example for that, see mlx5 QPs with type MLX5_IB_QPT_HW_GSI
+	 */
+	bool			valid;
+	/**
+	 * @no_track: don't add this entry to restrack DB
+	 *
+	 * This field is used to mark an entry that doesn't need to be added to
+	 * internal restrack DB and presented later to the users at the nldev
+	 * query stage.
+	 */
+	u8			no_track : 1;
+	/**
+	 * @kref: Protect destroy of the resource
+	 */
+	struct kref		kref;
+	/**
+	 * @comp: Signal that all consumers of resource are completed their work
+	 */
+	struct completion	comp;
+	/**
+	 * @task: owner of resource tracking entity
+	 *
+	 * There are two types of entities: created by user and created
+	 * by kernel.
+	 *
+	 * This is relevant for the entities created by users.
+	 * For the entities created by kernel, this pointer will be NULL.
+	 */
+	struct task_struct	*task;
+	/**
+	 * @kern_name: name of owner for the kernel created entities.
+	 */
+	const char		*kern_name;
+	/**
+	 * @type: various objects in restrack database
+	 */
+	enum rdma_restrack_type	type;
+	/**
+	 * @user: user resource
+	 */
+	bool			user;
+	/**
+	 * @id: ID to expose to users
+	 */
+	u32 id;
+};
+
+u32 rdma_restrack_count(struct ib_device *dev, enum rdma_restrack_type type,
+			bool show_details);
+/**
+ * rdma_is_kernel_res() - check the owner of resource
+ * @res:  resource entry
+ */
+static inline bool rdma_is_kernel_res(const struct rdma_restrack_entry *res)
+{
+	return !res->user;
+}
+
+/**
+ * rdma_restrack_get() - grab to protect resource from release
+ * @res:  resource entry
+ */
+int __must_check rdma_restrack_get(struct rdma_restrack_entry *res);
+
+/**
+ * rdma_restrack_put() - release resource
+ * @res:  resource entry
+ */
+int rdma_restrack_put(struct rdma_restrack_entry *res);
+
+/*
+ * Helper functions for rdma drivers when filling out
+ * nldev driver attributes.
+ */
+int rdma_nl_put_driver_u32(struct sk_buff *msg, const char *name, u32 value);
+int rdma_nl_put_driver_u32_hex(struct sk_buff *msg, const char *name,
+			       u32 value);
+int rdma_nl_put_driver_u64(struct sk_buff *msg, const char *name, u64 value);
+int rdma_nl_put_driver_u64_hex(struct sk_buff *msg, const char *name,
+			       u64 value);
+int rdma_nl_put_driver_string(struct sk_buff *msg, const char *name,
+			      const char *str);
+int rdma_nl_stat_hwcounter_entry(struct sk_buff *msg, const char *name,
+				 u64 value);
+
+struct rdma_restrack_entry *rdma_restrack_get_byid(struct ib_device *dev,
+						   enum rdma_restrack_type type,
+						   u32 id);
+
+/**
+ * rdma_restrack_no_track() - don't add resource to the DB
+ * @res: resource entry
+ *
+ * Every user of this API should be cross examined.
+ * Probably you don't need to use this function.
+ */
+static inline void rdma_restrack_no_track(struct rdma_restrack_entry *res)
+{
+	res->no_track = true;
+}
+static inline bool rdma_restrack_is_tracked(struct rdma_restrack_entry *res)
+{
+	return !res->no_track;
+}
+#endif /* _RDMA_RESTRACK_H_ */