Hi, I am splitting the bpf qdisc patchset into smaller landable sets and this is the first part. This patchset supports struct_ops operators that acquire kptrs through arguments and operators that return a kptr. A coming new struct_ops use case, bpf qdisc [0], has two operators that are not yet supported by current struct_ops infrastructure. Qdisc_ops::enqueue requires getting referenced skb kptr from the argument; Qdisc_ops::dequeue needs to return a referenced skb kptr. This patchset will allow bpf qdisc and other potential struct_ops implementers to do so. For struct_ops implementers: - To get a kptr from an argument, a struct_ops implementer needs to annotate the argument name in the stub function with "__ref" suffix. - The kptr return will automatically work as we now allow operators that return a struct pointer. - The verifier allows returning a null pointer. More control can be added later if there is a future struct_ops implementer only expecting valid pointers. For struct_ops users: - The referenced kptr acquired through the argument needs to be released or xchged into maps just like ones acquired via kfuncs. - To return a referenced kptr in struct_ops, 1) The type of the pointer must matches the return type 2) The pointer must comes from the kernel (not locally allocated), and 3) The pointer must be in its unmodified form [0] https://lore.kernel.org/bpf/20250210174336.2024258-1-ameryhung@xxxxxxxxx/ --- v1 - Fix missing kfree for ctx_arg_info Amery Hung (5): bpf: Make every prog keep a copy of ctx_arg_info bpf: Support getting referenced kptr from struct_ops argument selftests/bpf: Test referenced kptr arguments of struct_ops programs bpf: Allow struct_ops prog to return referenced kptr selftests/bpf: Test returning referenced kptr from struct_ops programs include/linux/bpf.h | 10 +- kernel/bpf/bpf_iter.c | 13 ++- kernel/bpf/bpf_struct_ops.c | 38 ++++++-- kernel/bpf/btf.c | 1 + kernel/bpf/syscall.c | 2 + kernel/bpf/verifier.c | 96 +++++++++++++++---- .../prog_tests/test_struct_ops_kptr_return.c | 16 ++++ .../prog_tests/test_struct_ops_refcounted.c | 12 +++ .../bpf/progs/struct_ops_kptr_return.c | 30 ++++++ ...uct_ops_kptr_return_fail__invalid_scalar.c | 26 +++++ .../struct_ops_kptr_return_fail__local_kptr.c | 34 +++++++ ...uct_ops_kptr_return_fail__nonzero_offset.c | 25 +++++ .../struct_ops_kptr_return_fail__wrong_type.c | 30 ++++++ .../bpf/progs/struct_ops_refcounted.c | 31 ++++++ ...ruct_ops_refcounted_fail__global_subprog.c | 39 ++++++++ .../struct_ops_refcounted_fail__ref_leak.c | 22 +++++ .../selftests/bpf/test_kmods/bpf_testmod.c | 15 +++ .../selftests/bpf/test_kmods/bpf_testmod.h | 6 ++ 18 files changed, 413 insertions(+), 33 deletions(-) create mode 100644 tools/testing/selftests/bpf/prog_tests/test_struct_ops_kptr_return.c create mode 100644 tools/testing/selftests/bpf/prog_tests/test_struct_ops_refcounted.c create mode 100644 tools/testing/selftests/bpf/progs/struct_ops_kptr_return.c create mode 100644 tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__invalid_scalar.c create mode 100644 tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__local_kptr.c create mode 100644 tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__nonzero_offset.c create mode 100644 tools/testing/selftests/bpf/progs/struct_ops_kptr_return_fail__wrong_type.c create mode 100644 tools/testing/selftests/bpf/progs/struct_ops_refcounted.c create mode 100644 tools/testing/selftests/bpf/progs/struct_ops_refcounted_fail__global_subprog.c create mode 100644 tools/testing/selftests/bpf/progs/struct_ops_refcounted_fail__ref_leak.c -- 2.47.1
