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Lee" , Daniel Borkmann , Alexei Starovoitov , netdev , jakub.kicinski@netronome.com Subject: Re: [v3,2/4] tools: bpftool: add net detach command to detach XDP on interface Message-ID: <20190807223807.00002740@gmail.com> In-Reply-To: References: <20190807022509.4214-1-danieltimlee@gmail.com> <20190807022509.4214-3-danieltimlee@gmail.com> <20190807203041.000020a8@gmail.com> X-Mailer: Claws Mail 3.17.1 (GTK+ 2.24.32; x86_64-w64-mingw32) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Wed, 7 Aug 2019 13:12:17 -0700 Y Song wrote: > On Wed, Aug 7, 2019 at 11:30 AM Maciej Fijalkowski > wrote: > > > > On Wed, 7 Aug 2019 10:02:04 -0700 > > Y Song wrote: > > > > > On Tue, Aug 6, 2019 at 7:25 PM Daniel T. Lee wrote: > > > > > > > > By this commit, using `bpftool net detach`, the attached XDP prog can > > > > be detached. Detaching the BPF prog will be done through libbpf > > > > 'bpf_set_link_xdp_fd' with the progfd set to -1. > > > > > > > > Signed-off-by: Daniel T. Lee > > > > --- > > > > tools/bpf/bpftool/net.c | 42 ++++++++++++++++++++++++++++++++++++++++- > > > > 1 file changed, 41 insertions(+), 1 deletion(-) > > > > > > > > diff --git a/tools/bpf/bpftool/net.c b/tools/bpf/bpftool/net.c > > > > index c05a3fac5cac..7be96acb08e0 100644 > > > > --- a/tools/bpf/bpftool/net.c > > > > +++ b/tools/bpf/bpftool/net.c > > > > @@ -343,6 +343,43 @@ static int do_attach(int argc, char **argv) > > > > return 0; > > > > } > > > > > > > > +static int do_detach(int argc, char **argv) > > > > +{ > > > > + enum net_attach_type attach_type; > > > > + int progfd, ifindex, err = 0; > > > > + > > > > + /* parse detach args */ > > > > + if (!REQ_ARGS(3)) > > > > + return -EINVAL; > > > > + > > > > + attach_type = parse_attach_type(*argv); > > > > + if (attach_type == max_net_attach_type) { > > > > + p_err("invalid net attach/detach type"); > > > > + return -EINVAL; > > > > + } > > > > + > > > > + NEXT_ARG(); > > > > + ifindex = net_parse_dev(&argc, &argv); > > > > + if (ifindex < 1) > > > > + return -EINVAL; > > > > + > > > > + /* detach xdp prog */ > > > > + progfd = -1; > > > > + if (is_prefix("xdp", attach_type_strings[attach_type])) > > > > + err = do_attach_detach_xdp(progfd, attach_type, ifindex, NULL); > > > > > > I found an issue here. This is probably related to do_attach_detach_xdp. > > > > > > -bash-4.4$ sudo ./bpftool net attach x pinned /sys/fs/bpf/xdp_example dev v1 > > > -bash-4.4$ sudo ./bpftool net > > > xdp: > > > v1(4) driver id 1172 > > > > > > tc: > > > eth0(2) clsact/ingress fbflow_icmp id 29 act [] > > > eth0(2) clsact/egress cls_fg_dscp_section id 27 act [] > > > eth0(2) clsact/egress fbflow_egress id 28 > > > eth0(2) clsact/egress fbflow_sslwall_egress id 35 > > > > > > flow_dissector: > > > > > > -bash-4.4$ sudo ./bpftool net detach x dev v2 > > > > Shouldn't this be v1 as dev? > > I am testing a scenario where with wrong devname > we did not return an error. Ah ok. In this scenario if driver has a native xdp support we would be invoking its ndo_bpf even if there's no prog currently attached and it wouldn't return error value. Looking at dev_xdp_uninstall, setting driver's prog to NULL is being done only when prog is attached. Maybe we should consider querying the driver in dev_change_xdp_fd regardless of passed fd value? E.g. don't query only when prog >= 0. I don't recall whether this was brought up previously. CCing Jakub so we have one thread. Maciej > > Yes, if dev "v1", it works as expected. > > > > > > -bash-4.4$ sudo ./bpftool net > > > xdp: > > > v1(4) driver id 1172 > > > > > > tc: > > > eth0(2) clsact/ingress fbflow_icmp id 29 act [] > > > eth0(2) clsact/egress cls_fg_dscp_section id 27 act [] > > > eth0(2) clsact/egress fbflow_egress id 28 > > > eth0(2) clsact/egress fbflow_sslwall_egress id 35 > > > > > > flow_dissector: > > > > > > -bash-4.4$ > > > > > > Basically detaching may fail due to wrong dev name or wrong type, etc. > > > But the tool did not return an error. Is this expected? > > > This may be related to this funciton "bpf_set_link_xdp_fd()". > > > So this patch itself should be okay. > > > > > > > + > > > > + if (err < 0) { > > > > + p_err("interface %s detach failed", > > > > + attach_type_strings[attach_type]); > > > > + return err; > > > > + } > > > > + > > > > + if (json_output) > > > > + jsonw_null(json_wtr); > > > > + > > > > + return 0; > > > > +} > > > > + > > > > static int do_show(int argc, char **argv) > > > > { > > > > struct bpf_attach_info attach_info = {}; > > > > @@ -419,6 +456,7 @@ static int do_help(int argc, char **argv) > > > > fprintf(stderr, > > > > "Usage: %s %s { show | list } [dev ]\n" > > > > " %s %s attach ATTACH_TYPE PROG dev [ overwrite ]\n" > > > > + " %s %s detach ATTACH_TYPE dev \n" > > > > " %s %s help\n" > > > > "\n" > > > > " " HELP_SPEC_PROGRAM "\n" > > > > @@ -429,7 +467,8 @@ static int do_help(int argc, char **argv) > > > > " to dump program attachments. For program types\n" > > > > " sk_{filter,skb,msg,reuseport} and lwt/seg6, please\n" > > > > " consult iproute2.\n", > > > > - bin_name, argv[-2], bin_name, argv[-2], bin_name, argv[-2]); > > > > + bin_name, argv[-2], bin_name, argv[-2], bin_name, argv[-2], > > > > + bin_name, argv[-2]); > > > > > > > > return 0; > > > > } > > > > @@ -438,6 +477,7 @@ static const struct cmd cmds[] = { > > > > { "show", do_show }, > > > > { "list", do_show }, > > > > { "attach", do_attach }, > > > > + { "detach", do_detach }, > > > > { "help", do_help }, > > > > { 0 } > > > > }; > > > > -- > > > > 2.20.1 > > > > > >