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From:   Jesper Dangaard Brouer <jbrouer@redhat.com>
Message-ID: <34152b76-88c8-0848-9f30-bd9755b1ee25@redhat.com>
Date:   Wed, 12 Apr 2023 19:52:45 +0200
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Subject: Re: [PATCH bpf V8 2/7] selftests/bpf: Add counters to xdp_hw_metadata
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To:     Stanislav Fomichev <sdf@google.com>
References: <168130333143.150247.11159481574477358816.stgit@firesoul>
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 <ZDbiofWhQhFEfIsr@google.com>
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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@redhat.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;
>>   	}