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, 102 insertions, 0 deletions

diff --git a/include/trace/events/thp.h b/include/trace/events/thp.h
new file mode 100644
index 000000000..c8fe879d5
--- /dev/null
+++ b/include/trace/events/thp.h
@@ -0,0 +1,102 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM thp
+
+#if !defined(_TRACE_THP_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_THP_H
+
+#include <linux/types.h>
+#include <linux/tracepoint.h>
+
+#ifdef CONFIG_PPC_BOOK3S_64
+DECLARE_EVENT_CLASS(hugepage_set,
+
+	    TP_PROTO(unsigned long addr, unsigned long pte),
+	    TP_ARGS(addr, pte),
+	    TP_STRUCT__entry(
+		    __field(unsigned long, addr)
+		    __field(unsigned long, pte)
+		    ),
+
+	    TP_fast_assign(
+		    __entry->addr = addr;
+		    __entry->pte = pte;
+		    ),
+
+	    TP_printk("Set page table entry with 0x%lx with 0x%lx", __entry->addr, __entry->pte)
+);
+
+DEFINE_EVENT(hugepage_set, hugepage_set_pmd,
+	    TP_PROTO(unsigned long addr, unsigned long pmd),
+	    TP_ARGS(addr, pmd)
+);
+
+DEFINE_EVENT(hugepage_set, hugepage_set_pud,
+	    TP_PROTO(unsigned long addr, unsigned long pud),
+	    TP_ARGS(addr, pud)
+);
+
+DECLARE_EVENT_CLASS(hugepage_update,
+
+	    TP_PROTO(unsigned long addr, unsigned long pte, unsigned long clr, unsigned long set),
+	    TP_ARGS(addr, pte, clr, set),
+	    TP_STRUCT__entry(
+		    __field(unsigned long, addr)
+		    __field(unsigned long, pte)
+		    __field(unsigned long, clr)
+		    __field(unsigned long, set)
+		    ),
+
+	    TP_fast_assign(
+		    __entry->addr = addr;
+		    __entry->pte = pte;
+		    __entry->clr = clr;
+		    __entry->set = set;
+
+		    ),
+
+	    TP_printk("hugepage update at addr 0x%lx and pte = 0x%lx clr = 0x%lx, set = 0x%lx", __entry->addr, __entry->pte, __entry->clr, __entry->set)
+);
+
+DEFINE_EVENT(hugepage_update, hugepage_update_pmd,
+	    TP_PROTO(unsigned long addr, unsigned long pmd, unsigned long clr, unsigned long set),
+	    TP_ARGS(addr, pmd, clr, set)
+);
+
+DEFINE_EVENT(hugepage_update, hugepage_update_pud,
+	    TP_PROTO(unsigned long addr, unsigned long pud, unsigned long clr, unsigned long set),
+	    TP_ARGS(addr, pud, clr, set)
+);
+#endif /* CONFIG_PPC_BOOK3S_64 */
+
+DECLARE_EVENT_CLASS(migration_pmd,
+
+		TP_PROTO(unsigned long addr, unsigned long pmd),
+
+		TP_ARGS(addr, pmd),
+
+		TP_STRUCT__entry(
+			__field(unsigned long, addr)
+			__field(unsigned long, pmd)
+		),
+
+		TP_fast_assign(
+			__entry->addr = addr;
+			__entry->pmd = pmd;
+		),
+		TP_printk("addr=%lx, pmd=%lx", __entry->addr, __entry->pmd)
+);
+
+DEFINE_EVENT(migration_pmd, set_migration_pmd,
+	TP_PROTO(unsigned long addr, unsigned long pmd),
+	TP_ARGS(addr, pmd)
+);
+
+DEFINE_EVENT(migration_pmd, remove_migration_pmd,
+	TP_PROTO(unsigned long addr, unsigned long pmd),
+	TP_ARGS(addr, pmd)
+);
+#endif /* _TRACE_THP_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>