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, 48 insertions, 0 deletions

diff --git a/tools/perf/util/mem-info.c b/tools/perf/util/mem-info.c
new file mode 100644
index 000000000..d3efa9c13
--- /dev/null
+++ b/tools/perf/util/mem-info.c
@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/zalloc.h>
+#include "mem-info.h"
+
+struct mem_info *mem_info__get(struct mem_info *mi)
+{
+	struct mem_info *result;
+
+	if (RC_CHK_GET(result, mi))
+		refcount_inc(mem_info__refcnt(mi));
+
+	return result;
+}
+
+void mem_info__put(struct mem_info *mi)
+{
+	if (mi && refcount_dec_and_test(mem_info__refcnt(mi))) {
+		addr_map_symbol__exit(mem_info__iaddr(mi));
+		addr_map_symbol__exit(mem_info__daddr(mi));
+		RC_CHK_FREE(mi);
+	} else {
+		RC_CHK_PUT(mi);
+	}
+}
+
+struct mem_info *mem_info__new(void)
+{
+	struct mem_info *result = NULL;
+	RC_STRUCT(mem_info) *mi = zalloc(sizeof(*mi));
+
+	if (ADD_RC_CHK(result, mi))
+		refcount_set(mem_info__refcnt(result), 1);
+
+	return result;
+}
+
+struct mem_info *mem_info__clone(struct mem_info *mi)
+{
+	struct mem_info *result = mem_info__new();
+
+	if (result) {
+		addr_map_symbol__copy(mem_info__iaddr(result), mem_info__iaddr(mi));
+		addr_map_symbol__copy(mem_info__daddr(result), mem_info__daddr(mi));
+		mem_info__data_src(result)->val = mem_info__data_src(mi)->val;
+	}
+
+	return result;
+}