Alexei Starovoitov <alexei.starovoitov@xxxxxxxxx> writes:
>> + struct mutex tgt_mutex; /* protects tgt_* pointers below, *after* prog becomes visible */
>> + struct bpf_prog *tgt_prog;
>> + struct bpf_trampoline *tgt_trampoline;
>> bool verifier_zext; /* Zero extensions has been inserted by verifier. */
>> bool offload_requested;
>> bool attach_btf_trace; /* true if attaching to BTF-enabled raw tp */
> ...
>> struct bpf_tracing_link {
>> struct bpf_link link;
>> enum bpf_attach_type attach_type;
>> + struct bpf_trampoline *trampoline;
>> + struct bpf_prog *tgt_prog;
>
> imo it's confusing to have 'tgt_prog' to mean two different things.
> In prog->aux->tgt_prog it means target prog to attach to in the future.
> Whereas here it means the existing prog that was used to attached to.
> They kinda both 'target progs' but would be good to disambiguate.
> May be keep it as 'tgt_prog' here and
> rename to 'dest_prog' and 'dest_trampoline' in prog->aux ?
I started changing this as you suggested, but I think it actually makes
the code weirder. We'll end up with a lot of 'tgt_prog =
prog->aux->dest_prog' assignments in the verifier, unless we also rename
all of the local variables, which I think is just code churn for very
little gain (the existing 'target' meaning is quite clear, I think).
I also think it's quite natural that the target moves; I mean, it's
literally the same pointer being re-assigned from prog->aux to the link.
We could rename the link member to 'attached_tgt_prog' or something like
that, but I'm not sure it helps (and I don't see much of a problem in
the first place).
WDYT?
-Toke
