Leon Hwang <[email protected]> writes: > 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.
Great, thanks! -Toke
