On 25/3/26 00:18, Toke Høiland-Jørgensen wrote: > Leon Hwang <[email protected]> writes: > >> xdp_has_frags was introduced by the commit >> c2f2cdbeffda ("bpf: introduce BPF_F_XDP_HAS_FRAGS flag in prog_flags loading >> the ebpf program"). >> >> The commit f45d5b6ce2e8 ("bpf: generalise tail call map compatibility check") >> was to ensure backwards compatibility against tail calls. However, it >> missed that XDP progs can be extended by freplace progs, which could break >> the backwards compatibility, e.g. xdp_has_frags=true freplace progs are >> allowed to attach to xdp_has_frags=false XDP progs. >> >> To avoid breaking the backwards compatibility via freplace, disallow >> freplace on XDP programs with different xdp_has_frags values. > > The problem you describe is not actually a problem, though? A > frags-aware program can run on a non-frags interface just fine. > > You're messing with long-standing behaviour (since 5.18!) to solve a > non-existent problem. In a way that completely breaks the frags handling > in libxdp[0]: > > Running tests from ./test-libxdp.sh > [test_link_so] PASS > [test_link_a] PASS > [test_old_dispatcher] PASS > [test_xdp_devbound] PASS > [test_xdp_frags] FAIL > Kernel supports XDP programs with frags > check_load_frags: FAILED > check_load_nofrags_success: PASSED > check_load_nofrags_fail: PASSED > check_load_frags_multi: FAILED > check_load_mix_big: FAILED > check_load_mix_small: FAILED > Test test_xdp_frags exited with return code: 1 > > > Please don't do that. > > -Toke > > [0] Run 'make test' here: https://github.com/xdp-project/xdp-tools >
Indeed, it failed to 'make test'. Will drop this patch in v2, as it wasn't an issue. Thanks, Leon
