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charset="UTF-8" User-Agent: Evolution 3.52.3-0ubuntu1 Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit On Tue, 2024-09-03 at 11:16 +0200, Matthieu Baerts wrote: > On 03/09/2024 11:11, Matthieu Baerts wrote: > > On 03/09/2024 10:04, Geliang Tang wrote: > > > From: Geliang Tang > > > > > > This patch adds a "cgroup/getsockopt" way to inspect the subflows > > > of a > > > mptcp socket. > > > > > > mptcp_for_each_stubflow() and other helpers related to > > > list_dentry are > > > added into progs/mptcp_bpf.h. > > > > > > Add an extra "cgroup/getsockopt" prog to walk the msk->conn_list > > > and use > > > bpf_core_cast to cast a pointer to tcp_sock for readonly. It will > > > allow > > > to inspect all the fields in a tcp_sock. > > > > (...) > > > > > diff --git a/tools/testing/selftests/bpf/progs/mptcp_subflow.c > > > b/tools/testing/selftests/bpf/progs/mptcp_subflow.c > > > index 2e28f4a215b5..1053a795eb43 100644 > > > --- a/tools/testing/selftests/bpf/progs/mptcp_subflow.c > > > +++ b/tools/testing/selftests/bpf/progs/mptcp_subflow.c > > > @@ -4,6 +4,7 @@ > > >   > > >  /* vmlinux.h, bpf_helpers.h and other 'define' */ > > >  #include "bpf_tracing_net.h" > > > +#include "mptcp_bpf.h" > > >   > > >  char _license[] SEC("license") = "GPL"; > > >   > > > @@ -57,3 +58,92 @@ int mptcp_subflow(struct bpf_sock_ops *skops) > > >   > > >   return 1; > > >  } > > > + > > > +static int _check_getsockopt_subflow_mark(struct bpf_sock *sk) > > > +{ > > > + struct mptcp_subflow_context *subflow; > > > + struct mptcp_sock *msk; > > > + int i = 0; > > > + > > > + if (sk->protocol != IPPROTO_MPTCP) { > > > + bpf_printk("MPTCP Subflow: unexpected protocol > > > %u", sk->protocol); > > > + return -1; > > > + } > > > > Out of curiosity, why did you move this code here and in > > _check_getsockopt_subflow_cc()? > > > > I'm just surprised because recently, you tried to reduce the amount > > of > > duplicated code :) > > While at it: it sounds better to have unique error messages, to know > where was the error. Here, a few messages are the same, e.g. > protocol, > number of subflows, sk is null. Do not hesitate to add something to > differentiate them: level & optname, a string prefix, the line > number, etc. No, I think we should drop all these "bpf_printk" messages. I checked all other BPF selftests programs, no one use these error messages to debug like this. Just "return 1" is enough: if (!sk || sk->protocol != IPPROTO_MPTCP) return 1; If a BPF program fail, its own load log will show: libbpf: prog '_getsockopt_subflow': -- BEGIN PROG LOAD LOG -- 0: R1=ctx() R10=fp0 ; int _getsockopt_subflow(struct bpf_sockopt *ctx) @ mptcp_subflow.c:136 0: (bf) r9 = r1 ; R1=ctx() R9_w=ctx() ; struct bpf_sock *sk = ctx->sk; @ mptcp_subflow.c:138 1: (79) r7 = *(u64 *)(r9 +0) ; R7_w=sock() R9_w=ctx() ; if (bpf_get_current_pid_tgid() >> 32 != pid) @ mptcp_subflow.c:141 2: (85) call bpf_get_current_pid_tgid#14 ; R0_w=scalar() No need to add any line number by ourselves. > > Cheers, > Matt