Re: [v2 PATCH bpf-next 2/4] bpftool: add net attach/detach command to tcx prog

[Tao Chen <chen.dylane@gmail.com>]

在 2024/7/20 00:17, Quentin Monnet 写道:
> On 17/07/2024 18:47, Tao Chen wrote:
>> Now, attach/detach tcx prog supported in libbpf, so we can add new
>> command 'bpftool attach/detach tcx' to attach tcx prog with bpftool
>> for user.
>>
>>   # bpftool prog load tc_prog.bpf.o /sys/fs/bpf/tc_prog
>>   # bpftool prog show
>> 	...
>> 	192: sched_cls  name tc_prog  tag 187aeb611ad00cfc  gpl
>> 	loaded_at 2024-07-11T15:58:16+0800  uid 0
>> 	xlated 152B  jited 97B  memlock 4096B  map_ids 100,99,97
>> 	btf_id 260
>>   # bpftool net attach tcx_ingress name tc_prog dev lo
>>   # bpftool net
>> 	...
>> 	tc:
>> 	lo(1) tcx/ingress tc_prog prog_id 29
>>
>>   # bpftool net detach tcx_ingress dev lo
>>   # bpftool net
>> 	...
>> 	tc:
>>   # bpftool net attach tcx_ingress name tc_prog dev lo
>>   # bpftool net
>> 	tc:
>> 	lo(1) tcx/ingress tc_prog prog_id 29
>>
>> Test environment: ubuntu_22_04, 6.7.0-060700-generic
>>
>> Signed-off-by: Tao Chen <chen.dylane@gmail.com>
>> ---
>>   tools/bpf/bpftool/net.c | 43 ++++++++++++++++++++++++++++++++++++++++-
>>   1 file changed, 42 insertions(+), 1 deletion(-)
>>
>> diff --git a/tools/bpf/bpftool/net.c b/tools/bpf/bpftool/net.c
>> index 1b9f4225b394..60b0af40109a 100644
>> --- a/tools/bpf/bpftool/net.c
>> +++ b/tools/bpf/bpftool/net.c
>> @@ -67,6 +67,8 @@ enum net_attach_type {
>>   	NET_ATTACH_TYPE_XDP_GENERIC,
>>   	NET_ATTACH_TYPE_XDP_DRIVER,
>>   	NET_ATTACH_TYPE_XDP_OFFLOAD,
>> +	NET_ATTACH_TYPE_TCX_INGRESS,
>> +	NET_ATTACH_TYPE_TCX_EGRESS,
>>   };
>>   
>>   static const char * const attach_type_strings[] = {
>> @@ -74,6 +76,8 @@ static const char * const attach_type_strings[] = {
>>   	[NET_ATTACH_TYPE_XDP_GENERIC]	= "xdpgeneric",
>>   	[NET_ATTACH_TYPE_XDP_DRIVER]	= "xdpdrv",
>>   	[NET_ATTACH_TYPE_XDP_OFFLOAD]	= "xdpoffload",
>> +	[NET_ATTACH_TYPE_TCX_INGRESS]	= "tcx_ingress",
>> +	[NET_ATTACH_TYPE_TCX_EGRESS]	= "tcx_egress",
>>   };
>>   
>>   static const char * const attach_loc_strings[] = {
>> @@ -647,6 +651,32 @@ static int do_attach_detach_xdp(int progfd, enum net_attach_type attach_type,
>>   	return bpf_xdp_attach(ifindex, progfd, flags, NULL);
>>   }
>>   
>> +static int get_tcx_type(enum net_attach_type attach_type)
>> +{
>> +	switch (attach_type) {
>> +	case NET_ATTACH_TYPE_TCX_INGRESS:
>> +		return BPF_TCX_INGRESS;
>> +	case NET_ATTACH_TYPE_TCX_EGRESS:
>> +		return BPF_TCX_EGRESS;
>> +	default:
>> +		return __MAX_BPF_ATTACH_TYPE;
> 
> 
> Can we return -1 here instead, please? In the current code, we validate
> the attach_type before entering this function and the "default" case is
> never reached, it's only here to discard compiler's warning. But if we
> ever reuse this function elsewhere, this could cause bugs: if the header
> file used for compiling the bpftool binary is not in sync with the
> header corresponding to the running kernel, __MAX_BPF_ATTACH_TYPE could
> correspond to a newly introduced type, and bpftool/libbpf would try to
> use that to attach the program, instead of detecting an error.
> 
> 

Hi, Quentin, i didn’t take the use case you mentioned into account. As 
you said, -1 looks more reasonable. I will fix it in the next revisions.

>> +	}
>> +}
>> +
>> +static int do_attach_tcx(int progfd, enum net_attach_type attach_type, int ifindex)
>> +{
>> +	int type = get_tcx_type(attach_type);
>> +
>> +	return bpf_prog_attach(progfd, ifindex, type, 0);
>> +}
>> +
>> +static int do_detach_tcx(int targetfd, enum net_attach_type attach_type)
>> +{
>> +	int type = get_tcx_type(attach_type);
>> +
>> +	return bpf_prog_detach(targetfd, type);
>> +}
>> +
>>   static int do_attach(int argc, char **argv)
>>   {
>>   	enum net_attach_type attach_type;
>> @@ -692,6 +722,11 @@ static int do_attach(int argc, char **argv)
>>   	case NET_ATTACH_TYPE_XDP_OFFLOAD:
>>   		err = do_attach_detach_xdp(progfd, attach_type, ifindex, overwrite);
>>   		break;
>> +	/* attach tcx prog */
>> +	case NET_ATTACH_TYPE_TCX_INGRESS:
>> +	case NET_ATTACH_TYPE_TCX_EGRESS:
>> +		err = do_attach_tcx(progfd, attach_type, ifindex);
>> +		break;
>>   	default:
>>   		break;
>>   	}
>> @@ -738,6 +773,11 @@ static int do_detach(int argc, char **argv)
>>   		progfd = -1;
>>   		err = do_attach_detach_xdp(progfd, attach_type, ifindex, NULL);
>>   		break;
>> +	/* detach tcx prog */
>> +	case NET_ATTACH_TYPE_TCX_INGRESS:
>> +	case NET_ATTACH_TYPE_TCX_EGRESS:
>> +		err = do_detach_tcx(ifindex, attach_type);
>> +		break;
>>   	default:
>>   		break;
>>   	}
>> @@ -944,7 +984,8 @@ static int do_help(int argc, char **argv)
>>   		"       %1$s %2$s help\n"
>>   		"\n"
>>   		"       " HELP_SPEC_PROGRAM "\n"
>> -		"       ATTACH_TYPE := { xdp | xdpgeneric | xdpdrv | xdpoffload }\n"
>> +		"       ATTACH_TYPE := { xdp | xdpgeneric | xdpdrv | xdpoffload | tcx_ingress\n"
>> +		"			 | tcx_egress }\n"
> 
>                   ^^^^^^^^^^^^^^^^^^^^^^^
> This indent space between the quote and the pipe needs to be spaces
> instead of three tabs, please.

My editor problem, i will fix it in the next revisions.

> 
> The rest of the patches looks good, thank you!
Thank you for reviewing all the patches. I appreciate your feedback.

> 
> Quentin
>
-- 
Best Regards
Dylane Chen