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, 51 insertions, 0 deletions

diff --git a/include/sound/util_mem.h b/include/sound/util_mem.h
new file mode 100644
index 000000000..01310e089
--- /dev/null
+++ b/include/sound/util_mem.h
@@ -0,0 +1,51 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef __SOUND_UTIL_MEM_H
+#define __SOUND_UTIL_MEM_H
+
+#include <linux/mutex.h>
+/*
+ *  Copyright (C) 2000 Takashi Iwai <tiwai@suse.de>
+ *
+ *  Generic memory management routines for soundcard memory allocation
+ */
+
+/*
+ * memory block
+ */
+struct snd_util_memblk {
+	unsigned int size;		/* size of this block */
+	unsigned int offset;		/* zero-offset of this block */
+	struct list_head list;		/* link */
+};
+
+#define snd_util_memblk_argptr(blk)	(void*)((char*)(blk) + sizeof(struct snd_util_memblk))
+
+/*
+ * memory management information
+ */
+struct snd_util_memhdr {
+	unsigned int size;		/* size of whole data */
+	struct list_head block;		/* block linked-list header */
+	int nblocks;			/* # of allocated blocks */
+	unsigned int used;		/* used memory size */
+	int block_extra_size;		/* extra data size of chunk */
+	struct mutex block_mutex;	/* lock */
+};
+
+/*
+ * prototypes
+ */
+struct snd_util_memhdr *snd_util_memhdr_new(int memsize);
+void snd_util_memhdr_free(struct snd_util_memhdr *hdr);
+struct snd_util_memblk *snd_util_mem_alloc(struct snd_util_memhdr *hdr, int size);
+int snd_util_mem_free(struct snd_util_memhdr *hdr, struct snd_util_memblk *blk);
+int snd_util_mem_avail(struct snd_util_memhdr *hdr);
+
+/* functions without mutex */
+struct snd_util_memblk *__snd_util_mem_alloc(struct snd_util_memhdr *hdr, int size);
+void __snd_util_mem_free(struct snd_util_memhdr *hdr, struct snd_util_memblk *blk);
+struct snd_util_memblk *__snd_util_memblk_new(struct snd_util_memhdr *hdr,
+					      unsigned int units,
+					      struct list_head *prev);
+
+#endif /* __SOUND_UTIL_MEM_H */