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, 63 insertions, 0 deletions

diff --git a/include/trace/events/tlb.h b/include/trace/events/tlb.h
new file mode 100644
index 000000000..fb8369511
--- /dev/null
+++ b/include/trace/events/tlb.h
@@ -0,0 +1,63 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM tlb
+
+#if !defined(_TRACE_TLB_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_TLB_H
+
+#include <linux/mm_types.h>
+#include <linux/tracepoint.h>
+
+#define TLB_FLUSH_REASON						\
+	EM(  TLB_FLUSH_ON_TASK_SWITCH,	"flush on task switch" )	\
+	EM(  TLB_REMOTE_SHOOTDOWN,	"remote shootdown" )		\
+	EM(  TLB_LOCAL_SHOOTDOWN,	"local shootdown" )		\
+	EM(  TLB_LOCAL_MM_SHOOTDOWN,	"local MM shootdown" )		\
+	EM(  TLB_REMOTE_SEND_IPI,	"remote IPI send" )		\
+	EMe( TLB_REMOTE_WRONG_CPU,	"remote wrong CPU" )
+
+/*
+ * First define the enums in TLB_FLUSH_REASON to be exported to userspace
+ * via TRACE_DEFINE_ENUM().
+ */
+#undef EM
+#undef EMe
+#define EM(a,b)		TRACE_DEFINE_ENUM(a);
+#define EMe(a,b)	TRACE_DEFINE_ENUM(a);
+
+TLB_FLUSH_REASON
+
+/*
+ * Now redefine the EM() and EMe() macros to map the enums to the strings
+ * that will be printed in the output.
+ */
+#undef EM
+#undef EMe
+#define EM(a,b)		{ a, b },
+#define EMe(a,b)	{ a, b }
+
+TRACE_EVENT(tlb_flush,
+
+	TP_PROTO(int reason, unsigned long pages),
+	TP_ARGS(reason, pages),
+
+	TP_STRUCT__entry(
+		__field(	  int, reason)
+		__field(unsigned long,  pages)
+	),
+
+	TP_fast_assign(
+		__entry->reason = reason;
+		__entry->pages  = pages;
+	),
+
+	TP_printk("pages:%ld reason:%s (%d)",
+		__entry->pages,
+		__print_symbolic(__entry->reason, TLB_FLUSH_REASON),
+		__entry->reason)
+);
+
+#endif /* _TRACE_TLB_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>