bpf: avoid rcu_dereference inside bpf_event_mutex lock region
During perf event attaching/detaching bpf programs, the tp_event->prog_array change is protected by the bpf_event_mutex lock in both attaching and deteching functions. Although tp_event->prog_array is a rcu pointer, rcu_derefrence is not needed to access it since mutex lock will guarantee ordering. Verified through "make C=2" that sparse locking check still happy with the new change. Also change the label name in perf_event_{attach,detach}_bpf_prog from "out" to "unlock" to reflect the code action after the label. Signed-off-by: Yonghong Song <yhs@fb.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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