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, 60 insertions, 0 deletions

diff --git a/samples/bpf/spintest.bpf.c b/samples/bpf/spintest.bpf.c
new file mode 100644
index 000000000..cba5a9d50
--- /dev/null
+++ b/samples/bpf/spintest.bpf.c
@@ -0,0 +1,60 @@
+/* Copyright (c) 2016, Facebook
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ */
+#include "vmlinux.h"
+#include <linux/version.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+#ifndef PERF_MAX_STACK_DEPTH
+#define PERF_MAX_STACK_DEPTH         127
+#endif
+
+struct {
+	__uint(type, BPF_MAP_TYPE_HASH);
+	__type(key, long);
+	__type(value, long);
+	__uint(max_entries, 1024);
+} my_map SEC(".maps");
+struct {
+	__uint(type, BPF_MAP_TYPE_PERCPU_HASH);
+	__uint(key_size, sizeof(long));
+	__uint(value_size, sizeof(long));
+	__uint(max_entries, 1024);
+} my_map2 SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_STACK_TRACE);
+	__uint(key_size, sizeof(u32));
+	__uint(value_size, PERF_MAX_STACK_DEPTH * sizeof(u64));
+	__uint(max_entries, 10000);
+} stackmap SEC(".maps");
+
+#define PROG(foo) \
+int foo(struct pt_regs *ctx) \
+{ \
+	long v = PT_REGS_IP(ctx), *val; \
+\
+	val = bpf_map_lookup_elem(&my_map, &v); \
+	bpf_map_update_elem(&my_map, &v, &v, BPF_ANY); \
+	bpf_map_update_elem(&my_map2, &v, &v, BPF_ANY); \
+	bpf_map_delete_elem(&my_map2, &v); \
+	bpf_get_stackid(ctx, &stackmap, BPF_F_REUSE_STACKID); \
+	return 0; \
+}
+
+/* add kprobes to all possible *spin* functions */
+SEC("kprobe.multi/spin_*lock*")PROG(spin_lock)
+SEC("kprobe.multi/*_spin_on_owner")PROG(spin_on_owner)
+SEC("kprobe.multi/_raw_spin_*lock*")PROG(raw_spin_lock)
+
+/* and to inner bpf helpers */
+SEC("kprobe/htab_map_update_elem")PROG(p15)
+SEC("kprobe/__htab_percpu_map_update_elem")PROG(p16)
+SEC("kprobe/htab_map_alloc")PROG(p17)
+
+char _license[] SEC("license") = "GPL";
+u32 _version SEC("version") = LINUX_VERSION_CODE;