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, 27 insertions, 0 deletions

diff --git a/sound/firewire/packets-buffer.h b/sound/firewire/packets-buffer.h
new file mode 100644
index 000000000..99e963c27
--- /dev/null
+++ b/sound/firewire/packets-buffer.h
@@ -0,0 +1,27 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef SOUND_FIREWIRE_PACKETS_BUFFER_H_INCLUDED
+#define SOUND_FIREWIRE_PACKETS_BUFFER_H_INCLUDED
+
+#include <linux/dma-mapping.h>
+#include <linux/firewire.h>
+
+/**
+ * struct iso_packets_buffer - manages a buffer for many packets
+ * @iso_buffer: the memory containing the packets
+ * @packets: an array, with each element pointing to one packet
+ */
+struct iso_packets_buffer {
+	struct fw_iso_buffer iso_buffer;
+	struct {
+		void *buffer;
+		unsigned int offset;
+	} *packets;
+};
+
+int iso_packets_buffer_init(struct iso_packets_buffer *b, struct fw_unit *unit,
+			    unsigned int count, unsigned int packet_size,
+			    enum dma_data_direction direction);
+void iso_packets_buffer_destroy(struct iso_packets_buffer *b,
+				struct fw_unit *unit);
+
+#endif