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, 74 insertions, 0 deletions

diff --git a/drivers/hid/hid-primax.c b/drivers/hid/hid-primax.c
new file mode 100644
index 000000000..8db054280
--- /dev/null
+++ b/drivers/hid/hid-primax.c
@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * HID driver for primax and similar keyboards with in-band modifiers
+ *
+ * Copyright 2011 Google Inc. All Rights Reserved
+ *
+ * Author:
+ *	Terry Lambert <tlambert@google.com>
+ */
+
+#include <linux/device.h>
+#include <linux/hid.h>
+#include <linux/module.h>
+
+#include "hid-ids.h"
+
+static int px_raw_event(struct hid_device *hid, struct hid_report *report,
+	 u8 *data, int size)
+{
+	int idx = size;
+
+	switch (report->id) {
+	case 0:		/* keyboard input */
+		/*
+		 * Convert in-band modifier key values into out of band
+		 * modifier bits and pull the key strokes from the report.
+		 * Thus a report data set which looked like:
+		 *
+		 * [00][00][E0][30][00][00][00][00]
+		 * (no modifier bits + "Left Shift" key + "1" key)
+		 *
+		 * Would be converted to:
+		 *
+		 * [01][00][00][30][00][00][00][00]
+		 * (Left Shift modifier bit + "1" key)
+		 *
+		 * As long as it's in the size range, the upper level
+		 * drivers don't particularly care if there are in-band
+		 * 0-valued keys, so they don't stop parsing.
+		 */
+		while (--idx > 1) {
+			if (data[idx] < 0xE0 || data[idx] > 0xE7)
+				continue;
+			data[0] |= (1 << (data[idx] - 0xE0));
+			data[idx] = 0;
+		}
+		hid_report_raw_event(hid, HID_INPUT_REPORT, data, size, size, 0);
+		return 1;
+
+	default:	/* unknown report */
+		/* Unknown report type; pass upstream */
+		hid_info(hid, "unknown report type %d\n", report->id);
+		break;
+	}
+
+	return 0;
+}
+
+static const struct hid_device_id px_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_PRIMAX, USB_DEVICE_ID_PRIMAX_KEYBOARD) },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, px_devices);
+
+static struct hid_driver px_driver = {
+	.name = "primax",
+	.id_table = px_devices,
+	.raw_event = px_raw_event,
+};
+module_hid_driver(px_driver);
+
+MODULE_AUTHOR("Terry Lambert <tlambert@google.com>");
+MODULE_DESCRIPTION("HID driver for primax and similar keyboards with in-band modifiers");
+MODULE_LICENSE("GPL");