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, 91 insertions, 0 deletions

diff --git a/drivers/input/serio/i8042.h b/drivers/input/serio/i8042.h
new file mode 100644
index 000000000..5f61672d5
--- /dev/null
+++ b/drivers/input/serio/i8042.h
@@ -0,0 +1,91 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef _I8042_H
+#define _I8042_H
+
+
+/*
+ *  Copyright (c) 1999-2002 Vojtech Pavlik
+ */
+
+/*
+ * Arch-dependent inline functions and defines.
+ */
+
+#if defined(CONFIG_MACH_JAZZ)
+#include "i8042-jazzio.h"
+#elif defined(CONFIG_SGI_HAS_I8042)
+#include "i8042-ip22io.h"
+#elif defined(CONFIG_SNI_RM)
+#include "i8042-snirm.h"
+#elif defined(CONFIG_SPARC)
+#include "i8042-sparcio.h"
+#elif defined(CONFIG_X86) || defined(CONFIG_LOONGARCH)
+#include "i8042-acpipnpio.h"
+#else
+#include "i8042-io.h"
+#endif
+
+/*
+ * This is in 50us units, the time we wait for the i8042 to react. This
+ * has to be long enough for the i8042 itself to timeout on sending a byte
+ * to a non-existent mouse.
+ */
+
+#define I8042_CTL_TIMEOUT	10000
+
+/*
+ * Return codes.
+ */
+
+#define I8042_RET_CTL_TEST	0x55
+
+/*
+ * Expected maximum internal i8042 buffer size. This is used for flushing
+ * the i8042 buffers.
+ */
+
+#define I8042_BUFFER_SIZE	16
+
+/*
+ * Number of AUX ports on controllers supporting active multiplexing
+ * specification
+ */
+
+#define I8042_NUM_MUX_PORTS	4
+
+/*
+ * Debug.
+ */
+
+#ifdef DEBUG
+static unsigned long i8042_start_time;
+#define dbg_init() do { i8042_start_time = jiffies; } while (0)
+#define dbg(format, arg...)							\
+	do {									\
+		if (i8042_debug)						\
+			printk(KERN_DEBUG KBUILD_MODNAME ": [%d] " format,	\
+			       (int) (jiffies - i8042_start_time), ##arg);	\
+	} while (0)
+
+#define filter_dbg(filter, data, format, args...)		\
+	do {							\
+		if (!i8042_debug)				\
+			break;					\
+								\
+		if (!filter || i8042_unmask_kbd_data)		\
+			dbg("%02x " format, data, ##args);	\
+		else						\
+			dbg("** " format, ##args);		\
+	} while (0)
+#else
+#define dbg_init() do { } while (0)
+#define dbg(format, arg...)							\
+	do {									\
+		if (0)								\
+			printk(KERN_DEBUG pr_fmt(format), ##arg);		\
+	} while (0)
+
+#define filter_dbg(filter, data, format, args...) do { } while (0)
+#endif
+
+#endif /* _I8042_H */