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, 68 insertions, 0 deletions

diff --git a/include/sound/seq_virmidi.h b/include/sound/seq_virmidi.h
new file mode 100644
index 000000000..359cb3633
--- /dev/null
+++ b/include/sound/seq_virmidi.h
@@ -0,0 +1,68 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef __SOUND_SEQ_VIRMIDI_H
+#define __SOUND_SEQ_VIRMIDI_H
+
+/*
+ *  Virtual Raw MIDI client on Sequencer
+ *  Copyright (c) 2000 by Takashi Iwai <tiwai@suse.de>,
+ *                        Jaroslav Kysela <perex@perex.cz>
+ */
+
+#include <sound/rawmidi.h>
+#include <sound/seq_midi_event.h>
+
+/*
+ * device file instance:
+ * This instance is created at each time the midi device file is
+ * opened.  Each instance has its own input buffer and MIDI parser
+ * (buffer), and is associated with the device instance.
+ */
+struct snd_virmidi {
+	struct list_head list;
+	int seq_mode;
+	int client;
+	int port;
+	bool trigger;
+	struct snd_midi_event *parser;
+	struct snd_seq_event event;
+	struct snd_virmidi_dev *rdev;
+	struct snd_rawmidi_substream *substream;
+	struct work_struct output_work;
+};
+
+#define SNDRV_VIRMIDI_SUBSCRIBE		(1<<0)
+#define SNDRV_VIRMIDI_USE		(1<<1)
+
+/*
+ * device record:
+ * Each virtual midi device has one device instance.  It contains
+ * common information and the linked-list of opened files, 
+ */
+struct snd_virmidi_dev {
+	struct snd_card *card;		/* associated card */
+	struct snd_rawmidi *rmidi;		/* rawmidi device */
+	int seq_mode;			/* SNDRV_VIRMIDI_XXX */
+	int device;			/* sequencer device */
+	int client;			/* created/attached client */
+	int port;			/* created/attached port */
+	unsigned int flags;		/* SNDRV_VIRMIDI_* */
+	struct rw_semaphore filelist_sem;
+	struct list_head filelist;
+};
+
+/* sequencer mode:
+ * ATTACH = input/output events from midi device are routed to the
+ *          attached sequencer port.  sequencer port is not created
+ *          by virmidi itself.
+ *          the input to rawmidi must be processed by passing the
+ *          incoming events via snd_virmidi_receive()
+ * DISPATCH = input/output events are routed to subscribers.
+ *            sequencer port is created in virmidi.
+ */
+#define SNDRV_VIRMIDI_SEQ_NONE		0
+#define SNDRV_VIRMIDI_SEQ_ATTACH	1
+#define SNDRV_VIRMIDI_SEQ_DISPATCH	2
+
+int snd_virmidi_new(struct snd_card *card, int device, struct snd_rawmidi **rrmidi);
+
+#endif /* __SOUND_SEQ_VIRMIDI */