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, 48 insertions, 0 deletions

diff --git a/tools/perf/util/cap.c b/tools/perf/util/cap.c
new file mode 100644
index 000000000..ac6d1d9a5
--- /dev/null
+++ b/tools/perf/util/cap.c
@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Capability utilities
+ */
+
+#include "cap.h"
+#include "debug.h"
+#include <errno.h>
+#include <string.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+
+#define MAX_LINUX_CAPABILITY_U32S _LINUX_CAPABILITY_U32S_3
+
+bool perf_cap__capable(int cap, bool *used_root)
+{
+	struct __user_cap_header_struct header = {
+		.version = _LINUX_CAPABILITY_VERSION_3,
+		.pid = 0,
+	};
+	struct __user_cap_data_struct data[MAX_LINUX_CAPABILITY_U32S] = {};
+	__u32 cap_val;
+
+	*used_root = false;
+	while (syscall(SYS_capget, &header, &data[0]) == -1) {
+		/* Retry, first attempt has set the header.version correctly. */
+		if (errno == EINVAL && header.version != _LINUX_CAPABILITY_VERSION_3 &&
+		    header.version == _LINUX_CAPABILITY_VERSION_1)
+			continue;
+
+		pr_debug2("capget syscall failed (%m) fall back on root check\n");
+		*used_root = true;
+		return geteuid() == 0;
+	}
+
+	/* Extract the relevant capability bit. */
+	if (cap >= 32) {
+		if (header.version == _LINUX_CAPABILITY_VERSION_3) {
+			cap_val = data[1].effective;
+		} else {
+			/* Capability beyond 32 is requested but only 32 are supported. */
+			return false;
+		}
+	} else {
+		cap_val = data[0].effective;
+	}
+	return (cap_val & (1 << (cap & 0x1f))) != 0;
+}