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, 71 insertions, 0 deletions

diff --git a/include/rdma/rdma_counter.h b/include/rdma/rdma_counter.h
new file mode 100644
index 000000000..4204d08a0
--- /dev/null
+++ b/include/rdma/rdma_counter.h
@@ -0,0 +1,71 @@
+/* SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB */
+/*
+ * Copyright (c) 2019 Mellanox Technologies. All rights reserved.
+ */
+
+#ifndef _RDMA_COUNTER_H_
+#define _RDMA_COUNTER_H_
+
+#include <linux/mutex.h>
+#include <linux/pid_namespace.h>
+
+#include <rdma/restrack.h>
+#include <rdma/rdma_netlink.h>
+
+struct ib_device;
+struct ib_qp;
+
+struct auto_mode_param {
+	int qp_type;
+};
+
+struct rdma_counter_mode {
+	enum rdma_nl_counter_mode mode;
+	enum rdma_nl_counter_mask mask;
+	struct auto_mode_param param;
+	bool bind_opcnt;
+};
+
+struct rdma_port_counter {
+	struct rdma_counter_mode mode;
+	struct rdma_hw_stats *hstats;
+	unsigned int num_counters;
+	struct mutex lock;
+};
+
+struct rdma_counter {
+	struct rdma_restrack_entry	res;
+	struct ib_device		*device;
+	uint32_t			id;
+	struct kref			kref;
+	struct rdma_counter_mode	mode;
+	struct mutex			lock;
+	struct rdma_hw_stats		*stats;
+	u32				port;
+};
+
+void rdma_counter_init(struct ib_device *dev);
+void rdma_counter_release(struct ib_device *dev);
+int rdma_counter_set_auto_mode(struct ib_device *dev, u32 port,
+			       enum rdma_nl_counter_mask mask,
+			       bool bind_opcnt,
+			       struct netlink_ext_ack *extack);
+int rdma_counter_bind_qp_auto(struct ib_qp *qp, u32 port);
+int rdma_counter_unbind_qp(struct ib_qp *qp, u32 port, bool force);
+
+int rdma_counter_query_stats(struct rdma_counter *counter);
+u64 rdma_counter_get_hwstat_value(struct ib_device *dev, u32 port, u32 index);
+int rdma_counter_bind_qpn(struct ib_device *dev, u32 port,
+			  u32 qp_num, u32 counter_id);
+int rdma_counter_bind_qpn_alloc(struct ib_device *dev, u32 port,
+				u32 qp_num, u32 *counter_id);
+int rdma_counter_unbind_qpn(struct ib_device *dev, u32 port,
+			    u32 qp_num, u32 counter_id);
+int rdma_counter_get_mode(struct ib_device *dev, u32 port,
+			  enum rdma_nl_counter_mode *mode,
+			  enum rdma_nl_counter_mask *mask,
+			  bool *opcnt);
+
+int rdma_counter_modify(struct ib_device *dev, u32 port,
+			unsigned int index, bool enable);
+#endif /* _RDMA_COUNTER_H_ */