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Commit c8c088ba authored by Yonghong Song's avatar Yonghong Song Committed by Daniel Borkmann
Browse files

bpf: set maximum number of attached progs to 64 for a single perf tp 



cgropu+bpf prog array has a maximum number of 64 programs.
Let us apply the same limit here.

Fixes: e87c6bc3 ("bpf: permit multiple bpf attachments for a single perf event")
Signed-off-by: default avatarYonghong Song <yhs@fb.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent 2b279419

kernel/bpf/core.c

+2 −1
Original line number Diff line number Diff line
@@ -1447,6 +1447,7 @@ int bpf_prog_array_length(struct bpf_prog_array __rcu *progs) 
	rcu_read_lock();

	prog = rcu_dereference(progs)->progs;

	for (; *prog; prog++)

		if (*prog != &dummy_bpf_prog.prog)

			cnt++;

	rcu_read_unlock();

	return cnt;

kernel/trace/bpf_trace.c

+8 −0
Original line number Diff line number Diff line
@@ -759,6 +759,8 @@ const struct bpf_prog_ops perf_event_prog_ops = { 


static DEFINE_MUTEX(bpf_event_mutex);



#define BPF_TRACE_MAX_PROGS 64



int perf_event_attach_bpf_prog(struct perf_event *event,

			       struct bpf_prog *prog)

{
@@ -772,6 +774,12 @@ int perf_event_attach_bpf_prog(struct perf_event *event, 
		goto unlock;



	old_array = event->tp_event->prog_array;

	if (old_array &&

	    bpf_prog_array_length(old_array) >= BPF_TRACE_MAX_PROGS) {

		ret = -E2BIG;

		goto unlock;

	}



	ret = bpf_prog_array_copy(old_array, NULL, prog, &new_array);

	if (ret < 0)

		goto unlock;