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, 108 insertions, 0 deletions

diff --git a/include/trace/events/rwmmio.h b/include/trace/events/rwmmio.h
new file mode 100644
index 000000000..a43e5dd74
--- /dev/null
+++ b/include/trace/events/rwmmio.h
@@ -0,0 +1,108 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2021-2022 Qualcomm Innovation Center, Inc. All rights reserved.
+ */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM rwmmio
+
+#if !defined(_TRACE_RWMMIO_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_RWMMIO_H
+
+#include <linux/tracepoint.h>
+
+DECLARE_EVENT_CLASS(rwmmio_rw_template,
+
+	TP_PROTO(unsigned long caller, unsigned long caller0, u64 val, u8 width,
+		 volatile void __iomem *addr),
+
+	TP_ARGS(caller, caller0, val, width, addr),
+
+	TP_STRUCT__entry(
+		__field(unsigned long, caller)
+		__field(unsigned long, caller0)
+		__field(unsigned long, addr)
+		__field(u64, val)
+		__field(u8, width)
+	),
+
+	TP_fast_assign(
+		__entry->caller = caller;
+		__entry->caller0 = caller0;
+		__entry->val = val;
+		__entry->addr = (unsigned long)addr;
+		__entry->width = width;
+	),
+
+	TP_printk("%pS -> %pS width=%d val=%#llx addr=%#lx",
+		(void *)__entry->caller0, (void *)__entry->caller, __entry->width,
+		__entry->val, __entry->addr)
+);
+
+DEFINE_EVENT(rwmmio_rw_template, rwmmio_write,
+	TP_PROTO(unsigned long caller, unsigned long caller0, u64 val, u8 width,
+		 volatile void __iomem *addr),
+	TP_ARGS(caller, caller0, val, width, addr)
+);
+
+DEFINE_EVENT(rwmmio_rw_template, rwmmio_post_write,
+	TP_PROTO(unsigned long caller, unsigned long caller0, u64 val, u8 width,
+		 volatile void __iomem *addr),
+	TP_ARGS(caller, caller0, val, width, addr)
+);
+
+TRACE_EVENT(rwmmio_read,
+
+	TP_PROTO(unsigned long caller, unsigned long caller0, u8 width,
+		 const volatile void __iomem *addr),
+
+	TP_ARGS(caller, caller0, width, addr),
+
+	TP_STRUCT__entry(
+		__field(unsigned long, caller)
+		__field(unsigned long, caller0)
+		__field(unsigned long, addr)
+		__field(u8, width)
+	),
+
+	TP_fast_assign(
+		__entry->caller = caller;
+		__entry->caller0 = caller0;
+		__entry->addr = (unsigned long)addr;
+		__entry->width = width;
+	),
+
+	TP_printk("%pS -> %pS width=%d addr=%#lx",
+		 (void *)__entry->caller0, (void *)__entry->caller, __entry->width, __entry->addr)
+);
+
+TRACE_EVENT(rwmmio_post_read,
+
+	TP_PROTO(unsigned long caller, unsigned long caller0, u64 val, u8 width,
+		 const volatile void __iomem *addr),
+
+	TP_ARGS(caller, caller0, val, width, addr),
+
+	TP_STRUCT__entry(
+		__field(unsigned long, caller)
+		__field(unsigned long, caller0)
+		__field(unsigned long, addr)
+		__field(u64, val)
+		__field(u8, width)
+	),
+
+	TP_fast_assign(
+		__entry->caller = caller;
+		__entry->caller0 = caller0;
+		__entry->val = val;
+		__entry->addr = (unsigned long)addr;
+		__entry->width = width;
+	),
+
+	TP_printk("%pS -> %pS width=%d val=%#llx addr=%#lx",
+		 (void *)__entry->caller0, (void *)__entry->caller, __entry->width,
+		 __entry->val, __entry->addr)
+);
+
+#endif /* _TRACE_RWMMIO_H */
+
+#include <trace/define_trace.h>