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, 146 insertions, 0 deletions

diff --git a/include/trace/events/i2c.h b/include/trace/events/i2c.h
new file mode 100644
index 000000000..142a23c65
--- /dev/null
+++ b/include/trace/events/i2c.h
@@ -0,0 +1,146 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/* I2C message transfer tracepoints
+ *
+ * Copyright (C) 2013 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM i2c
+
+#if !defined(_TRACE_I2C_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_I2C_H
+
+#include <linux/i2c.h>
+#include <linux/tracepoint.h>
+
+/*
+ * drivers/i2c/i2c-core-base.c
+ */
+extern int i2c_transfer_trace_reg(void);
+extern void i2c_transfer_trace_unreg(void);
+
+/*
+ * __i2c_transfer() write request
+ */
+TRACE_EVENT_FN(i2c_write,
+	       TP_PROTO(const struct i2c_adapter *adap, const struct i2c_msg *msg,
+			int num),
+	       TP_ARGS(adap, msg, num),
+	       TP_STRUCT__entry(
+		       __field(int,	adapter_nr		)
+		       __field(__u16,	msg_nr			)
+		       __field(__u16,	addr			)
+		       __field(__u16,	flags			)
+		       __field(__u16,	len			)
+		       __dynamic_array(__u8, buf, msg->len)	),
+	       TP_fast_assign(
+		       __entry->adapter_nr = adap->nr;
+		       __entry->msg_nr = num;
+		       __entry->addr = msg->addr;
+		       __entry->flags = msg->flags;
+		       __entry->len = msg->len;
+		       memcpy(__get_dynamic_array(buf), msg->buf, msg->len);
+			      ),
+	       TP_printk("i2c-%d #%u a=%03x f=%04x l=%u [%*phD]",
+			 __entry->adapter_nr,
+			 __entry->msg_nr,
+			 __entry->addr,
+			 __entry->flags,
+			 __entry->len,
+			 __entry->len, __get_dynamic_array(buf)
+			 ),
+	       i2c_transfer_trace_reg,
+	       i2c_transfer_trace_unreg);
+
+/*
+ * __i2c_transfer() read request
+ */
+TRACE_EVENT_FN(i2c_read,
+	       TP_PROTO(const struct i2c_adapter *adap, const struct i2c_msg *msg,
+			int num),
+	       TP_ARGS(adap, msg, num),
+	       TP_STRUCT__entry(
+		       __field(int,	adapter_nr		)
+		       __field(__u16,	msg_nr			)
+		       __field(__u16,	addr			)
+		       __field(__u16,	flags			)
+		       __field(__u16,	len			)
+				),
+	       TP_fast_assign(
+		       __entry->adapter_nr = adap->nr;
+		       __entry->msg_nr = num;
+		       __entry->addr = msg->addr;
+		       __entry->flags = msg->flags;
+		       __entry->len = msg->len;
+			      ),
+	       TP_printk("i2c-%d #%u a=%03x f=%04x l=%u",
+			 __entry->adapter_nr,
+			 __entry->msg_nr,
+			 __entry->addr,
+			 __entry->flags,
+			 __entry->len
+			 ),
+	       i2c_transfer_trace_reg,
+		       i2c_transfer_trace_unreg);
+
+/*
+ * __i2c_transfer() read reply
+ */
+TRACE_EVENT_FN(i2c_reply,
+	       TP_PROTO(const struct i2c_adapter *adap, const struct i2c_msg *msg,
+			int num),
+	       TP_ARGS(adap, msg, num),
+	       TP_STRUCT__entry(
+		       __field(int,	adapter_nr		)
+		       __field(__u16,	msg_nr			)
+		       __field(__u16,	addr			)
+		       __field(__u16,	flags			)
+		       __field(__u16,	len			)
+		       __dynamic_array(__u8, buf, msg->len)	),
+	       TP_fast_assign(
+		       __entry->adapter_nr = adap->nr;
+		       __entry->msg_nr = num;
+		       __entry->addr = msg->addr;
+		       __entry->flags = msg->flags;
+		       __entry->len = msg->len;
+		       memcpy(__get_dynamic_array(buf), msg->buf, msg->len);
+			      ),
+	       TP_printk("i2c-%d #%u a=%03x f=%04x l=%u [%*phD]",
+			 __entry->adapter_nr,
+			 __entry->msg_nr,
+			 __entry->addr,
+			 __entry->flags,
+			 __entry->len,
+			 __entry->len, __get_dynamic_array(buf)
+			 ),
+	       i2c_transfer_trace_reg,
+	       i2c_transfer_trace_unreg);
+
+/*
+ * __i2c_transfer() result
+ */
+TRACE_EVENT_FN(i2c_result,
+	       TP_PROTO(const struct i2c_adapter *adap, int num, int ret),
+	       TP_ARGS(adap, num, ret),
+	       TP_STRUCT__entry(
+		       __field(int,	adapter_nr		)
+		       __field(__u16,	nr_msgs			)
+		       __field(__s16,	ret			)
+				),
+	       TP_fast_assign(
+		       __entry->adapter_nr = adap->nr;
+		       __entry->nr_msgs = num;
+		       __entry->ret = ret;
+			      ),
+	       TP_printk("i2c-%d n=%u ret=%d",
+			 __entry->adapter_nr,
+			 __entry->nr_msgs,
+			 __entry->ret
+			 ),
+	       i2c_transfer_trace_reg,
+	       i2c_transfer_trace_unreg);
+
+#endif /* _TRACE_I2C_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>