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, 94 insertions, 0 deletions

diff --git a/drivers/input/misc/rave-sp-pwrbutton.c b/drivers/input/misc/rave-sp-pwrbutton.c
new file mode 100644
index 000000000..bcab3cdb7
--- /dev/null
+++ b/drivers/input/misc/rave-sp-pwrbutton.c
@@ -0,0 +1,94 @@
+// SPDX-License-Identifier: GPL-2.0+
+//
+// Power Button driver for RAVE SP
+//
+// Copyright (C) 2017 Zodiac Inflight Innovations
+//
+//
+
+#include <linux/input.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mfd/rave-sp.h>
+#include <linux/platform_device.h>
+
+#define RAVE_SP_EVNT_BUTTON_PRESS	(RAVE_SP_EVNT_BASE + 0x00)
+
+struct rave_sp_power_button {
+	struct input_dev *idev;
+	struct notifier_block nb;
+};
+
+static int rave_sp_power_button_event(struct notifier_block *nb,
+				      unsigned long action, void *data)
+{
+	struct rave_sp_power_button *pb =
+		container_of(nb, struct rave_sp_power_button, nb);
+	const u8 event = rave_sp_action_unpack_event(action);
+	const u8 value = rave_sp_action_unpack_value(action);
+	struct input_dev *idev = pb->idev;
+
+	if (event == RAVE_SP_EVNT_BUTTON_PRESS) {
+		input_report_key(idev, KEY_POWER, value);
+		input_sync(idev);
+
+		return NOTIFY_STOP;
+	}
+
+	return NOTIFY_DONE;
+}
+
+static int rave_sp_pwrbutton_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct rave_sp_power_button *pb;
+	struct input_dev *idev;
+	int error;
+
+	pb = devm_kzalloc(dev, sizeof(*pb), GFP_KERNEL);
+	if (!pb)
+		return -ENOMEM;
+
+	idev = devm_input_allocate_device(dev);
+	if (!idev)
+		return -ENOMEM;
+
+	idev->name = pdev->name;
+
+	input_set_capability(idev, EV_KEY, KEY_POWER);
+
+	error = input_register_device(idev);
+	if (error)
+		return error;
+
+	pb->idev = idev;
+	pb->nb.notifier_call = rave_sp_power_button_event;
+	pb->nb.priority = 128;
+
+	error = devm_rave_sp_register_event_notifier(dev, &pb->nb);
+	if (error)
+		return error;
+
+	return 0;
+}
+
+static const struct of_device_id rave_sp_pwrbutton_of_match[] = {
+	{ .compatible = "zii,rave-sp-pwrbutton" },
+	{}
+};
+
+static struct platform_driver rave_sp_pwrbutton_driver = {
+	.probe = rave_sp_pwrbutton_probe,
+	.driver	= {
+		.name = KBUILD_MODNAME,
+		.of_match_table = rave_sp_pwrbutton_of_match,
+	},
+};
+module_platform_driver(rave_sp_pwrbutton_driver);
+
+MODULE_DEVICE_TABLE(of, rave_sp_pwrbutton_of_match);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Andrey Vostrikov <andrey.vostrikov@cogentembedded.com>");
+MODULE_AUTHOR("Nikita Yushchenko <nikita.yoush@cogentembedded.com>");
+MODULE_AUTHOR("Andrey Smirnov <andrew.smirnov@gmail.com>");
+MODULE_DESCRIPTION("RAVE SP Power Button driver");