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, 52 insertions, 0 deletions

diff --git a/tools/perf/util/tracepoint.c b/tools/perf/util/tracepoint.c
new file mode 100644
index 000000000..95377ed5d
--- /dev/null
+++ b/tools/perf/util/tracepoint.c
@@ -0,0 +1,52 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "tracepoint.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/param.h>
+#include <unistd.h>
+
+#include <api/fs/tracing_path.h>
+#include "fncache.h"
+
+int tp_event_has_id(const char *dir_path, struct dirent *evt_dir)
+{
+	char evt_path[MAXPATHLEN];
+	int fd;
+
+	snprintf(evt_path, MAXPATHLEN, "%s/%s/id", dir_path, evt_dir->d_name);
+	fd = open(evt_path, O_RDONLY);
+	if (fd < 0)
+		return -EINVAL;
+	close(fd);
+
+	return 0;
+}
+
+/*
+ * Check whether event is in <debugfs_mount_point>/tracing/events
+ */
+bool is_valid_tracepoint(const char *event_string)
+{
+	char *dst, *path = malloc(strlen(event_string) + 4); /* Space for "/id\0". */
+	bool have_file = false; /* Conservatively return false if memory allocation failed. */
+	const char *src;
+
+	if (!path)
+		return false;
+
+	/* Copy event_string replacing the ':' with '/'. */
+	for (src = event_string, dst = path; *src; src++, dst++)
+		*dst = (*src == ':') ? '/' : *src;
+	/* Add "/id\0". */
+	memcpy(dst, "/id", 4);
+
+	dst = get_events_file(path);
+	if (dst)
+		have_file = file_available(dst);
+	free(dst);
+	free(path);
+	return have_file;
+}