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, 153 insertions, 0 deletions

diff --git a/drivers/input/keyboard/stowaway.c b/drivers/input/keyboard/stowaway.c
new file mode 100644
index 000000000..eade05542
--- /dev/null
+++ b/drivers/input/keyboard/stowaway.c
@@ -0,0 +1,153 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Stowaway keyboard driver for Linux
+ */
+
+/*
+ *  Copyright (c) 2006 Marek Vasut
+ *
+ *  Based on Newton keyboard driver for Linux
+ *  by Justin Cormack
+ */
+
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/input.h>
+#include <linux/serio.h>
+
+#define DRIVER_DESC	"Stowaway keyboard driver"
+
+MODULE_AUTHOR("Marek Vasut <marek.vasut@gmail.com>");
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_LICENSE("GPL");
+
+#define SKBD_KEY_MASK	0x7f
+#define SKBD_RELEASE	0x80
+
+static unsigned char skbd_keycode[128] = {
+	KEY_1, KEY_2, KEY_3, KEY_Z, KEY_4, KEY_5, KEY_6, KEY_7,
+	0, KEY_Q, KEY_W, KEY_E, KEY_R, KEY_T, KEY_Y, KEY_GRAVE,
+	KEY_X, KEY_A, KEY_S, KEY_D, KEY_F, KEY_G, KEY_H, KEY_SPACE,
+	KEY_CAPSLOCK, KEY_TAB, KEY_LEFTCTRL, 0, 0, 0, 0, 0,
+	0, 0, 0, KEY_LEFTALT, 0, 0, 0, 0,
+	0, 0, 0, 0, KEY_C, KEY_V, KEY_B, KEY_N,
+	KEY_MINUS, KEY_EQUAL, KEY_BACKSPACE, KEY_HOME, KEY_8, KEY_9, KEY_0, KEY_ESC,
+	KEY_LEFTBRACE, KEY_RIGHTBRACE, KEY_BACKSLASH, KEY_END, KEY_U, KEY_I, KEY_O, KEY_P,
+	KEY_APOSTROPHE, KEY_ENTER, KEY_PAGEUP,0, KEY_J, KEY_K, KEY_L, KEY_SEMICOLON,
+	KEY_SLASH, KEY_UP, KEY_PAGEDOWN, 0,KEY_M, KEY_COMMA, KEY_DOT, KEY_INSERT,
+	KEY_DELETE, KEY_LEFT, KEY_DOWN, KEY_RIGHT,  0, 0, 0,
+	KEY_LEFTSHIFT, KEY_RIGHTSHIFT, 0, 0, 0, 0, 0,
+	0, 0, 0, 0, 0, 0, 0, 0,
+	0, 0, 0, 0, 0, 0, 0, 0,
+	0, KEY_F1, KEY_F2, KEY_F3, KEY_F4, KEY_F5, KEY_F6, KEY_F7,
+	KEY_F8, KEY_F9, KEY_F10, KEY_F11, KEY_F12, 0, 0, 0
+};
+
+struct skbd {
+	unsigned char keycode[128];
+	struct input_dev *dev;
+	struct serio *serio;
+	char phys[32];
+};
+
+static irqreturn_t skbd_interrupt(struct serio *serio, unsigned char data,
+				  unsigned int flags)
+{
+	struct skbd *skbd = serio_get_drvdata(serio);
+	struct input_dev *dev = skbd->dev;
+
+	if (skbd->keycode[data & SKBD_KEY_MASK]) {
+		input_report_key(dev, skbd->keycode[data & SKBD_KEY_MASK],
+				 !(data & SKBD_RELEASE));
+		input_sync(dev);
+	}
+
+	return IRQ_HANDLED;
+}
+
+static int skbd_connect(struct serio *serio, struct serio_driver *drv)
+{
+	struct skbd *skbd;
+	struct input_dev *input_dev;
+	int err = -ENOMEM;
+	int i;
+
+	skbd = kzalloc_obj(*skbd);
+	input_dev = input_allocate_device();
+	if (!skbd || !input_dev)
+		goto fail1;
+
+	skbd->serio = serio;
+	skbd->dev = input_dev;
+	snprintf(skbd->phys, sizeof(skbd->phys), "%s/input0", serio->phys);
+	memcpy(skbd->keycode, skbd_keycode, sizeof(skbd->keycode));
+
+	input_dev->name = "Stowaway Keyboard";
+	input_dev->phys = skbd->phys;
+	input_dev->id.bustype = BUS_RS232;
+	input_dev->id.vendor = SERIO_STOWAWAY;
+	input_dev->id.product = 0x0001;
+	input_dev->id.version = 0x0100;
+	input_dev->dev.parent = &serio->dev;
+
+	input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_REP);
+	input_dev->keycode = skbd->keycode;
+	input_dev->keycodesize = sizeof(unsigned char);
+	input_dev->keycodemax = ARRAY_SIZE(skbd_keycode);
+	for (i = 0; i < ARRAY_SIZE(skbd_keycode); i++)
+		set_bit(skbd_keycode[i], input_dev->keybit);
+	clear_bit(0, input_dev->keybit);
+
+	serio_set_drvdata(serio, skbd);
+
+	err = serio_open(serio, drv);
+	if (err)
+		goto fail2;
+
+	err = input_register_device(skbd->dev);
+	if (err)
+		goto fail3;
+
+	return 0;
+
+ fail3: serio_close(serio);
+ fail2:	serio_set_drvdata(serio, NULL);
+ fail1:	input_free_device(input_dev);
+	kfree(skbd);
+	return err;
+}
+
+static void skbd_disconnect(struct serio *serio)
+{
+	struct skbd *skbd = serio_get_drvdata(serio);
+
+	serio_close(serio);
+	serio_set_drvdata(serio, NULL);
+	input_unregister_device(skbd->dev);
+	kfree(skbd);
+}
+
+static const struct serio_device_id skbd_serio_ids[] = {
+	{
+		.type	= SERIO_RS232,
+		.proto	= SERIO_STOWAWAY,
+		.id	= SERIO_ANY,
+		.extra	= SERIO_ANY,
+	},
+	{ 0 }
+};
+
+MODULE_DEVICE_TABLE(serio, skbd_serio_ids);
+
+static struct serio_driver skbd_drv = {
+	.driver		= {
+		.name	= "stowaway",
+	},
+	.description	= DRIVER_DESC,
+	.id_table	= skbd_serio_ids,
+	.interrupt	= skbd_interrupt,
+	.connect	= skbd_connect,
+	.disconnect	= skbd_disconnect,
+};
+
+module_serio_driver(skbd_drv);