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, 79 insertions, 0 deletions

diff --git a/include/media/cec-pin.h b/include/media/cec-pin.h
new file mode 100644
index 000000000..483bc4769
--- /dev/null
+++ b/include/media/cec-pin.h
@@ -0,0 +1,79 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * cec-pin.h - low-level CEC pin control
+ *
+ * Copyright 2017 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
+ */
+
+#ifndef LINUX_CEC_PIN_H
+#define LINUX_CEC_PIN_H
+
+#include <linux/types.h>
+#include <media/cec.h>
+
+/**
+ * struct cec_pin_ops - low-level CEC pin operations
+ * @read:	read the CEC pin. Returns > 0 if high, 0 if low, or an error
+ *		if negative.
+ * @low:	drive the CEC pin low.
+ * @high:	stop driving the CEC pin. The pull-up will drive the pin
+ *		high, unless someone else is driving the pin low.
+ * @enable_irq:	optional, enable the interrupt to detect pin voltage changes.
+ * @disable_irq: optional, disable the interrupt.
+ * @free:	optional. Free any allocated resources. Called when the
+ *		adapter is deleted.
+ * @status:	optional, log status information.
+ * @read_hpd:	optional. Read the HPD pin. Returns > 0 if high, 0 if low or
+ *		an error if negative.
+ * @read_5v:	optional. Read the 5V pin. Returns > 0 if high, 0 if low or
+ *		an error if negative.
+ * @received:	optional. High-level CEC message callback. Allows the driver
+ *		to process CEC messages.
+ *
+ * These operations (except for the @received op) are used by the
+ * cec pin framework to manipulate the CEC pin.
+ */
+struct cec_pin_ops {
+	int  (*read)(struct cec_adapter *adap);
+	void (*low)(struct cec_adapter *adap);
+	void (*high)(struct cec_adapter *adap);
+	bool (*enable_irq)(struct cec_adapter *adap);
+	void (*disable_irq)(struct cec_adapter *adap);
+	void (*free)(struct cec_adapter *adap);
+	void (*status)(struct cec_adapter *adap, struct seq_file *file);
+	int  (*read_hpd)(struct cec_adapter *adap);
+	int  (*read_5v)(struct cec_adapter *adap);
+
+	/* High-level CEC message callback */
+	int (*received)(struct cec_adapter *adap, struct cec_msg *msg);
+};
+
+/**
+ * cec_pin_changed() - update pin state from interrupt
+ *
+ * @adap:	pointer to the cec adapter
+ * @value:	when true the pin is high, otherwise it is low
+ *
+ * If changes of the CEC voltage are detected via an interrupt, then
+ * cec_pin_changed is called from the interrupt with the new value.
+ */
+void cec_pin_changed(struct cec_adapter *adap, bool value);
+
+/**
+ * cec_pin_allocate_adapter() - allocate a pin-based cec adapter
+ *
+ * @pin_ops:	low-level pin operations
+ * @priv:	will be stored in adap->priv and can be used by the adapter ops.
+ *		Use cec_get_drvdata(adap) to get the priv pointer.
+ * @name:	the name of the CEC adapter. Note: this name will be copied.
+ * @caps:	capabilities of the CEC adapter. This will be ORed with
+ *		CEC_CAP_MONITOR_ALL and CEC_CAP_MONITOR_PIN.
+ *
+ * Allocate a cec adapter using the cec pin framework.
+ *
+ * Return: a pointer to the cec adapter or an error pointer
+ */
+struct cec_adapter *cec_pin_allocate_adapter(const struct cec_pin_ops *pin_ops,
+					void *priv, const char *name, u32 caps);
+
+#endif