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, 67 insertions, 0 deletions

diff --git a/include/sound/hwdep.h b/include/sound/hwdep.h
new file mode 100644
index 000000000..b0da63318
--- /dev/null
+++ b/include/sound/hwdep.h
@@ -0,0 +1,67 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef __SOUND_HWDEP_H
+#define __SOUND_HWDEP_H
+
+/*
+ *  Hardware dependent layer 
+ *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>
+ */
+
+#include <sound/asound.h>
+#include <linux/poll.h>
+
+struct snd_hwdep;
+
+/* hwdep file ops; all ops can be NULL */
+struct snd_hwdep_ops {
+	long long (*llseek)(struct snd_hwdep *hw, struct file *file,
+			    long long offset, int orig);
+	long (*read)(struct snd_hwdep *hw, char __user *buf,
+		     long count, loff_t *offset);
+	long (*write)(struct snd_hwdep *hw, const char __user *buf,
+		      long count, loff_t *offset);
+	int (*open)(struct snd_hwdep *hw, struct file * file);
+	int (*release)(struct snd_hwdep *hw, struct file * file);
+	__poll_t (*poll)(struct snd_hwdep *hw, struct file *file,
+			     poll_table *wait);
+	int (*ioctl)(struct snd_hwdep *hw, struct file *file,
+		     unsigned int cmd, unsigned long arg);
+	int (*ioctl_compat)(struct snd_hwdep *hw, struct file *file,
+			    unsigned int cmd, unsigned long arg);
+	int (*mmap)(struct snd_hwdep *hw, struct file *file,
+		    struct vm_area_struct *vma);
+	int (*dsp_status)(struct snd_hwdep *hw,
+			  struct snd_hwdep_dsp_status *status);
+	int (*dsp_load)(struct snd_hwdep *hw,
+			struct snd_hwdep_dsp_image *image);
+};
+
+struct snd_hwdep {
+	struct snd_card *card;
+	struct list_head list;
+	int device;
+	char id[32];
+	char name[80];
+	int iface;
+
+#ifdef CONFIG_SND_OSSEMUL
+	int oss_type;
+	int ossreg;
+#endif
+
+	struct snd_hwdep_ops ops;
+	wait_queue_head_t open_wait;
+	void *private_data;
+	void (*private_free) (struct snd_hwdep *hwdep);
+	struct device *dev;
+
+	struct mutex open_mutex;
+	int used;			/* reference counter */
+	unsigned int dsp_loaded;	/* bit fields of loaded dsp indices */
+	unsigned int exclusive:1;	/* exclusive access mode */
+};
+
+extern int snd_hwdep_new(struct snd_card *card, char *id, int device,
+			 struct snd_hwdep **rhwdep);
+
+#endif /* __SOUND_HWDEP_H */