1 // SPDX-License-Identifier: GPL-2.0 2 3 #include <linux/bpf.h> 4 #include <bpf/bpf_helpers.h> 5 6 __noinline 7 long changes_pkt_data(struct __sk_buff *sk) 8 { 9 return bpf_skb_pull_data(sk, 0); 10 } 11 12 __noinline __weak 13 long does_not_change_pkt_data(struct __sk_buff *sk) 14 { 15 return 0; 16 } 17 18 SEC("?tc") 19 int main_with_subprogs(struct __sk_buff *sk) 20 { 21 changes_pkt_data(sk); 22 does_not_change_pkt_data(sk); 23 return 0; 24 } 25 26 SEC("?tc") 27 int main_changes(struct __sk_buff *sk) 28 { 29 bpf_skb_pull_data(sk, 0); 30 return 0; 31 } 32 33 SEC("?tc") 34 int main_does_not_change(struct __sk_buff *sk) 35 { 36 return 0; 37 } 38 39 char _license[] SEC("license") = "GPL"; 40