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/drivers/extcon/extcon.h b/drivers/extcon/extcon.h
new file mode 100644
index 000000000..946182687
--- /dev/null
+++ b/drivers/extcon/extcon.h
@@ -0,0 +1,68 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __LINUX_EXTCON_INTERNAL_H__
+#define __LINUX_EXTCON_INTERNAL_H__
+
+#include <linux/extcon-provider.h>
+
+/**
+ * struct extcon_dev - An extcon device represents one external connector.
+ * @name:		The name of this extcon device. Parent device name is
+ *			used if NULL.
+ * @supported_cable:	Array of supported cable names ending with EXTCON_NONE.
+ *			If supported_cable is NULL, cable name related APIs
+ *			are disabled.
+ * @mutually_exclusive:	Array of mutually exclusive set of cables that cannot
+ *			be attached simultaneously. The array should be
+ *			ending with 0 or be NULL (no mutually exclusive cables).
+ *			For example, if it is {0x7, 0x30, 0}, then,
+ *			{0, 1}, {0, 1, 2}, {0, 2}, {1, 2}, or {4, 5} cannot
+ *			be attached simulataneously. {0x7, 0} is equivalent to
+ *			{0x3, 0x6, 0x5, 0}. If it is {0xFFFFFFFF, 0}, there
+ *			can be no simultaneous connections.
+ * @dev:		Device of this extcon.
+ * @id:			Unique device ID of this extcon.
+ * @state:		Attach/detach state of this extcon. Do not provide at
+ *			register-time.
+ * @nh_all:		Notifier for the state change events for all supported
+ *			external connectors from this extcon.
+ * @nh:			Notifier for the state change events from this extcon
+ * @entry:		To support list of extcon devices so that users can
+ *			search for extcon devices based on the extcon name.
+ * @lock:		Protects device state and serialises device registration
+ * @max_supported:	Internal value to store the number of cables.
+ * @extcon_dev_type:	Device_type struct to provide attribute_groups
+ *			customized for each extcon device.
+ * @cables:		Sysfs subdirectories. Each represents one cable.
+ *
+ * In most cases, users only need to provide "User initializing data" of
+ * this struct when registering an extcon. In some exceptional cases,
+ * optional callbacks may be needed. However, the values in "internal data"
+ * are overwritten by register function.
+ */
+struct extcon_dev {
+	/* Optional user initializing data */
+	const char *name;
+	const unsigned int *supported_cable;
+	const u32 *mutually_exclusive;
+
+	/* Internal data. Please do not set. */
+	struct device dev;
+	unsigned int id;
+	struct raw_notifier_head nh_all;
+	struct raw_notifier_head *nh;
+	struct list_head entry;
+	int max_supported;
+	spinlock_t lock;	/* could be called by irq handler */
+	u32 state;
+
+	/* /sys/class/extcon/.../cable.n/... */
+	struct device_type extcon_dev_type;
+	struct extcon_cable *cables;
+
+	/* /sys/class/extcon/.../mutually_exclusive/... */
+	struct attribute_group attr_g_muex;
+	struct attribute **attrs_muex;
+	struct device_attribute *d_attrs_muex;
+};
+
+#endif /* __LINUX_EXTCON_INTERNAL_H__ */