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, 138 insertions, 0 deletions

diff --git a/include/trace/events/cma.h b/include/trace/events/cma.h
new file mode 100644
index 000000000..37195edf2
--- /dev/null
+++ b/include/trace/events/cma.h
@@ -0,0 +1,138 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM cma
+
+#if !defined(_TRACE_CMA_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_CMA_H
+
+#include <linux/types.h>
+#include <linux/tracepoint.h>
+
+TRACE_EVENT(cma_release,
+
+	TP_PROTO(const char *name, unsigned long pfn, const struct page *page,
+		 unsigned long count),
+
+	TP_ARGS(name, pfn, page, count),
+
+	TP_STRUCT__entry(
+		__string(name, name)
+		__field(unsigned long, pfn)
+		__field(const struct page *, page)
+		__field(unsigned long, count)
+	),
+
+	TP_fast_assign(
+		__assign_str(name);
+		__entry->pfn = pfn;
+		__entry->page = page;
+		__entry->count = count;
+	),
+
+	TP_printk("name=%s pfn=0x%lx page=%p count=%lu",
+		  __get_str(name),
+		  __entry->pfn,
+		  __entry->page,
+		  __entry->count)
+);
+
+TRACE_EVENT(cma_alloc_start,
+
+	TP_PROTO(const char *name, unsigned long request_count, unsigned long available_count,
+		unsigned long total_count, unsigned int align),
+
+	TP_ARGS(name, request_count, available_count, total_count, align),
+
+	TP_STRUCT__entry(
+		__string(name, name)
+		__field(unsigned long, request_count)
+		__field(unsigned long, available_count)
+		__field(unsigned long, total_count)
+		__field(unsigned int, align)
+	),
+
+	TP_fast_assign(
+		__assign_str(name);
+		__entry->request_count = request_count;
+		__entry->available_count = available_count;
+		__entry->total_count = total_count;
+		__entry->align = align;
+	),
+
+	TP_printk("name=%s request_count=%lu available_count=%lu total_count=%lu align=%u",
+		  __get_str(name),
+		  __entry->request_count,
+		  __entry->available_count,
+		  __entry->total_count,
+		  __entry->align)
+);
+
+TRACE_EVENT(cma_alloc_finish,
+
+	TP_PROTO(const char *name, unsigned long pfn, const struct page *page,
+		 unsigned long count, unsigned int align, int errorno),
+
+	TP_ARGS(name, pfn, page, count, align, errorno),
+
+	TP_STRUCT__entry(
+		__string(name, name)
+		__field(unsigned long, pfn)
+		__field(const struct page *, page)
+		__field(unsigned long, count)
+		__field(unsigned int, align)
+		__field(int, errorno)
+	),
+
+	TP_fast_assign(
+		__assign_str(name);
+		__entry->pfn = pfn;
+		__entry->page = page;
+		__entry->count = count;
+		__entry->align = align;
+		__entry->errorno = errorno;
+	),
+
+	TP_printk("name=%s pfn=0x%lx page=%p count=%lu align=%u errorno=%d",
+		  __get_str(name),
+		  __entry->pfn,
+		  __entry->page,
+		  __entry->count,
+		  __entry->align,
+		  __entry->errorno)
+);
+
+TRACE_EVENT(cma_alloc_busy_retry,
+
+	TP_PROTO(const char *name, unsigned long pfn, const struct page *page,
+		 unsigned long count, unsigned int align),
+
+	TP_ARGS(name, pfn, page, count, align),
+
+	TP_STRUCT__entry(
+		__string(name, name)
+		__field(unsigned long, pfn)
+		__field(const struct page *, page)
+		__field(unsigned long, count)
+		__field(unsigned int, align)
+	),
+
+	TP_fast_assign(
+		__assign_str(name);
+		__entry->pfn = pfn;
+		__entry->page = page;
+		__entry->count = count;
+		__entry->align = align;
+	),
+
+	TP_printk("name=%s pfn=0x%lx page=%p count=%lu align=%u",
+		  __get_str(name),
+		  __entry->pfn,
+		  __entry->page,
+		  __entry->count,
+		  __entry->align)
+);
+
+#endif /* _TRACE_CMA_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>