workqueue: skip the node_nr_active update for non-unbound workqueuesgrafted

apply_wqattrs_commit() updates node_nr_active->max unconditionally.
wq->node_nr_active[] is only allocated for unbound workqueues, so guard
the call before per-cpu workqueues start using this path.

No functional change: only unbound workqueues reach apply_wqattrs_*()
today.

Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Tejun Heo <tj@kernel.org>

1 files changed, 36 insertions, 0 deletions

diff --git a/tools/perf/util/smt.c b/tools/perf/util/smt.c
new file mode 100644
index 000000000..650e804d0
--- /dev/null
+++ b/tools/perf/util/smt.c
@@ -0,0 +1,36 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <string.h>
+#include "api/fs/fs.h"
+#include "cputopo.h"
+#include "smt.h"
+
+bool smt_on(void)
+{
+	static bool cached;
+	static bool cached_result;
+	int fs_value;
+
+	if (cached)
+		return cached_result;
+
+	if (sysfs__read_int("devices/system/cpu/smt/active", &fs_value) >= 0)
+		cached_result = (fs_value == 1);
+	else
+		cached_result = cpu_topology__smt_on(online_topology());
+
+	cached = true;
+	return cached_result;
+}
+
+bool core_wide(bool system_wide, const char *user_requested_cpu_list)
+{
+	/* If not everything running on a core is being recorded then we can't use core_wide. */
+	if (!system_wide)
+		return false;
+
+	/* Cheap case that SMT is disabled and therefore we're inherently core_wide. */
+	if (!smt_on())
+		return true;
+
+	return cpu_topology__core_wide(online_topology(), user_requested_cpu_list);
+}