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

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

Fixes: e87c6bc385 ("bpf: permit multiple bpf attachments for a single perf event")
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Yonghong Song 2017-11-30 13:47:54 -08:00 committed by Daniel Borkmann
parent 2b27941956
commit c8c088ba0e
2 changed files with 10 additions and 1 deletions
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3
kernel/bpf/core.c
View File

@ -1447,7 +1447,8 @@ int bpf_prog_array_length(struct bpf_prog_array __rcu *progs)
rcu_read_lock();
prog = rcu_dereference(progs)->progs;
for (; *prog; prog++)
cnt++;
if (*prog != &dummy_bpf_prog.prog)
cnt++;
rcu_read_unlock();
return cnt;
}

8
kernel/trace/bpf_trace.c
View File

@ -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;