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, 91 insertions, 0 deletions

diff --git a/block/blk-mq-debugfs.h b/block/blk-mq-debugfs.h
new file mode 100644
index 000000000..49bb1aaa8
--- /dev/null
+++ b/block/blk-mq-debugfs.h
@@ -0,0 +1,91 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef INT_BLK_MQ_DEBUGFS_H
+#define INT_BLK_MQ_DEBUGFS_H
+
+#ifdef CONFIG_BLK_DEBUG_FS
+
+#include <linux/seq_file.h>
+
+struct blk_mq_hw_ctx;
+
+struct blk_mq_debugfs_attr {
+	const char *name;
+	umode_t mode;
+	int (*show)(void *, struct seq_file *);
+	ssize_t (*write)(void *, const char __user *, size_t, loff_t *);
+	/* Set either .show or .seq_ops. */
+	const struct seq_operations *seq_ops;
+};
+
+int __blk_mq_debugfs_rq_show(struct seq_file *m, struct request *rq);
+int blk_mq_debugfs_rq_show(struct seq_file *m, void *v);
+
+void blk_mq_debugfs_register(struct request_queue *q);
+void blk_mq_debugfs_register_hctx(struct request_queue *q,
+				  struct blk_mq_hw_ctx *hctx);
+void blk_mq_debugfs_unregister_hctx(struct blk_mq_hw_ctx *hctx);
+void blk_mq_debugfs_register_hctxs(struct request_queue *q);
+void blk_mq_debugfs_unregister_hctxs(struct request_queue *q);
+
+void blk_mq_debugfs_register_sched(struct request_queue *q);
+void blk_mq_debugfs_unregister_sched(struct request_queue *q);
+void blk_mq_debugfs_register_sched_hctx(struct request_queue *q,
+				       struct blk_mq_hw_ctx *hctx);
+void blk_mq_debugfs_unregister_sched_hctx(struct blk_mq_hw_ctx *hctx);
+
+void blk_mq_debugfs_register_rq_qos(struct request_queue *q);
+#else
+static inline void blk_mq_debugfs_register(struct request_queue *q)
+{
+}
+
+static inline void blk_mq_debugfs_register_hctx(struct request_queue *q,
+						struct blk_mq_hw_ctx *hctx)
+{
+}
+
+static inline void blk_mq_debugfs_unregister_hctx(struct blk_mq_hw_ctx *hctx)
+{
+}
+
+static inline void blk_mq_debugfs_register_hctxs(struct request_queue *q)
+{
+}
+
+static inline void blk_mq_debugfs_unregister_hctxs(struct request_queue *q)
+{
+}
+
+static inline void blk_mq_debugfs_register_sched(struct request_queue *q)
+{
+}
+
+static inline void blk_mq_debugfs_unregister_sched(struct request_queue *q)
+{
+}
+
+static inline void blk_mq_debugfs_register_sched_hctx(struct request_queue *q,
+						      struct blk_mq_hw_ctx *hctx)
+{
+}
+
+static inline void blk_mq_debugfs_unregister_sched_hctx(struct blk_mq_hw_ctx *hctx)
+{
+}
+
+static inline void blk_mq_debugfs_register_rq_qos(struct request_queue *q)
+{
+}
+
+#endif
+
+#if defined(CONFIG_BLK_DEV_ZONED) && defined(CONFIG_BLK_DEBUG_FS)
+int queue_zone_wplugs_show(void *data, struct seq_file *m);
+#else
+static inline int queue_zone_wplugs_show(void *data, struct seq_file *m)
+{
+	return 0;
+}
+#endif
+
+#endif