netdev - Re: [PATCH bpf V8 2/7] selftests/bpf: Add counters to xdp_hw

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Date:   Wed, 12 Apr 2023 19:52:45 +0200
From:   Jesper Dangaard Brouer <jbrouer@...hat.com>
To:     Stanislav Fomichev <sdf@...gle.com>
Cc:     brouer@...hat.com, bpf@...r.kernel.org,
        Toke Høiland-Jørgensen <toke@...hat.com>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        martin.lau@...nel.org, ast@...nel.org, daniel@...earbox.net,
        alexandr.lobakin@...el.com, larysa.zaremba@...el.com,
        xdp-hints@...-project.net, anthony.l.nguyen@...el.com,
        yoong.siang.song@...el.com, boon.leong.ong@...el.com,
        intel-wired-lan@...ts.osuosl.org, pabeni@...hat.com,
        jesse.brandeburg@...el.com, kuba@...nel.org, edumazet@...gle.com,
        john.fastabend@...il.com, hawk@...nel.org, davem@...emloft.net,
        tariqt@...dia.com, saeedm@...dia.com, leon@...nel.org,
        linux-rdma@...r.kernel.org
Subject: Re: [PATCH bpf V8 2/7] selftests/bpf: Add counters to xdp_hw_metadata


On 12/04/2023 18.56, Stanislav Fomichev wrote:
> On 04/12, Jesper Dangaard Brouer wrote:
>> Add counters for skipped, failed and redirected packets.
>> The xdp_hw_metadata program only redirects UDP port 9091.
>> This helps users to quickly identify then packets are
>> skipped and identify failures of bpf_xdp_adjust_meta.
>>
>> Signed-off-by: Jesper Dangaard Brouer <brouer@...hat.com>
>> ---
>>   .../testing/selftests/bpf/progs/xdp_hw_metadata.c  |   15 +++++++++++++--
>>   tools/testing/selftests/bpf/xdp_hw_metadata.c      |    4 +++-
>>   2 files changed, 16 insertions(+), 3 deletions(-)
>>
>> diff --git a/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c b/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c
>> index b0104763405a..a07ef7534013 100644
>> --- a/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c
>> +++ b/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c
>> @@ -25,6 +25,10 @@ struct {
>>   	__type(value, __u32);
>>   } xsk SEC(".maps");
>>   
>> +volatile __u64 pkts_skip = 0;
>> +volatile __u64 pkts_fail = 0;
>> +volatile __u64 pkts_redir = 0;
>> +
>>   extern int bpf_xdp_metadata_rx_timestamp(const struct xdp_md *ctx,
>>   					 __u64 *timestamp) __ksym;
>>   extern int bpf_xdp_metadata_rx_hash(const struct xdp_md *ctx,
>> @@ -59,16 +63,21 @@ int rx(struct xdp_md *ctx)
>>   			udp = NULL;
>>   	}
>>   
>> -	if (!udp)
>> +	if (!udp) {
>> +		pkts_skip++;
>>   		return XDP_PASS;
>> +	}
>>   
>>   	/* Forwarding UDP:9091 to AF_XDP */
>> -	if (udp->dest != bpf_htons(9091))
>> +	if (udp->dest != bpf_htons(9091)) {
>> +		pkts_skip++;
>>   		return XDP_PASS;
>> +	}
>>   
>>   	ret = bpf_xdp_adjust_meta(ctx, -(int)sizeof(struct xdp_meta));
>>   	if (ret != 0) {
> 
> [..]
> 
>>   		bpf_printk("bpf_xdp_adjust_meta returned %d", ret);
> 
> Maybe let's remove these completely? Merge patch 1 and 2, remove printk,
> add counters. We can add more counters in the future if the existing
> ones are not enough.. WDYT?
> 

Sure, lets just remove all of the bpf_printk, and add these counter instead.
Rolling V9.

>> +		pkts_fail++;

This fail counter should be enough for driver devel to realize that they
also need to implement/setup XDP metadata pointers correctly (for
bpf_xdp_adjust_meta to work).

>>   		return XDP_PASS;
>>   	}