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Message-ID: <3b9b51d4-95c5-4f31-afb1-246dd9b00467@quicinc.com>
Date: Thu, 9 May 2024 12:24:36 -0700
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Subject: Re: [RFC PATCH bpf-next v7 3/3] selftests/bpf: Handle forwarding of
 UDP CLOCK_TAI packets
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To: Martin KaFai Lau <martin.lau@linux.dev>
CC: "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet
	<edumazet@google.com>, Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni
	<pabeni@redhat.com>, <netdev@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>, Andrew Halaney <ahalaney@redhat.com>,
        "Willem
 de Bruijn" <willemdebruijn.kernel@gmail.com>,
        Martin KaFai Lau
	<martin.lau@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>, bpf
	<bpf@vger.kernel.org>,
        <kernel@quicinc.com>
References: <20240508215842.2449798-1-quic_abchauha@quicinc.com>
 <20240508215842.2449798-4-quic_abchauha@quicinc.com>
 <c929dced-e70e-4f49-b812-026b2677bfd9@linux.dev>
From: "Abhishek Chauhan (ABC)" <quic_abchauha@quicinc.com>
In-Reply-To: <c929dced-e70e-4f49-b812-026b2677bfd9@linux.dev>
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On 5/9/2024 12:17 PM, Martin KaFai Lau wrote:
> On 5/8/24 2:58 PM, Abhishek Chauhan wrote:
>> With changes in the design to forward CLOCK_TAI in the skbuff
>> framework,  existing selftest framework needs modification
>> to handle forwarding of UDP packets with CLOCK_TAI as clockid.
> 
> The set lgtm. I have a few final nits on the test.
> 
>>
>> Link: https://lore.kernel.org/netdev/bc037db4-58bb-4861-ac31-a361a93841d3@linux.dev/
>> Signed-off-by: Abhishek Chauhan <quic_abchauha@quicinc.com>
>> ---
>> Changes since v7
>> - Fixed  issues in the ctx_rewrite.c
>>    with respect to dissembly in both
>>    .read and .write
>>
>> Changes since v6
>> - Moved all the selftest to another patch
>>
>> Changes since v1 - v5
>> - Patch was not present
>>
>>   tools/include/uapi/linux/bpf.h                | 15 ++++---
>>   .../selftests/bpf/prog_tests/ctx_rewrite.c    | 10 +++--
>>   .../selftests/bpf/prog_tests/tc_redirect.c    |  3 --
>>   .../selftests/bpf/progs/test_tc_dtime.c       | 39 +++++++++----------
>>   4 files changed, 34 insertions(+), 33 deletions(-)
>>
>> diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
>> index 90706a47f6ff..25ea393cf084 100644
>> --- a/tools/include/uapi/linux/bpf.h
>> +++ b/tools/include/uapi/linux/bpf.h
> 
> nit. Please move this bpf.h sync changes to patch 2 where the uapi changes happen.
> 
>> @@ -6207,12 +6207,17 @@ union {                    \
>>       __u64 :64;            \
>>   } __attribute__((aligned(8)))
>>   +/* The enum used in skb->tstamp_type. It specifies the clock type
>> + * of the time stored in the skb->tstamp.
>> + */
>>   enum {
>> -    BPF_SKB_TSTAMP_UNSPEC,
>> -    BPF_SKB_TSTAMP_DELIVERY_MONO,    /* tstamp has mono delivery time */
>> -    /* For any BPF_SKB_TSTAMP_* that the bpf prog cannot handle,
>> -     * the bpf prog should handle it like BPF_SKB_TSTAMP_UNSPEC
>> -     * and try to deduce it by ingress, egress or skb->sk->sk_clockid.
>> +    BPF_SKB_TSTAMP_UNSPEC = 0,        /* DEPRECATED */
>> +    BPF_SKB_TSTAMP_DELIVERY_MONO = 1,    /* DEPRECATED */
>> +    BPF_SKB_CLOCK_REALTIME = 0,
>> +    BPF_SKB_CLOCK_MONOTONIC = 1,
>> +    BPF_SKB_CLOCK_TAI = 2,
>> +    /* For any future BPF_SKB_CLOCK_* that the bpf prog cannot handle,
>> +     * the bpf prog can try to deduce it by ingress/egress/skb->sk->sk_clockid.
>>        */
>>   };
>>   diff --git a/tools/testing/selftests/bpf/prog_tests/ctx_rewrite.c b/tools/testing/selftests/bpf/prog_tests/ctx_rewrite.c
>> index 3b7c57fe55a5..08b6391f2f56 100644
>> --- a/tools/testing/selftests/bpf/prog_tests/ctx_rewrite.c
>> +++ b/tools/testing/selftests/bpf/prog_tests/ctx_rewrite.c
>> @@ -69,15 +69,17 @@ static struct test_case test_cases[] = {
>>       {
>>           N(SCHED_CLS, struct __sk_buff, tstamp),
>>           .read  = "r11 = *(u8 *)($ctx + sk_buff::__mono_tc_offset);"
>> -             "w11 &= 3;"
>> -             "if w11 != 0x3 goto pc+2;"
>> +             "if w11 & 0x4 goto pc+1;"
>> +             "goto pc+4;"
>> +             "if w11 & 0x3 goto pc+1;"
>> +             "goto pc+2;"
>>                "$dst = 0;"
>>                "goto pc+1;"
>>                "$dst = *(u64 *)($ctx + sk_buff::tstamp);",
>>           .write = "r11 = *(u8 *)($ctx + sk_buff::__mono_tc_offset);"
>> -             "if w11 & 0x2 goto pc+1;"
>> +             "if w11 & 0x4 goto pc+1;"
>>                "goto pc+2;"
>> -             "w11 &= -2;"
>> +             "w11 &= -4;"
>>                "*(u8 *)($ctx + sk_buff::__mono_tc_offset) = r11;"
>>                "*(u64 *)($ctx + sk_buff::tstamp) = $src;",
>>       },
>> diff --git a/tools/testing/selftests/bpf/prog_tests/tc_redirect.c b/tools/testing/selftests/bpf/prog_tests/tc_redirect.c
>> index b1073d36d77a..327d51f59142 100644
>> --- a/tools/testing/selftests/bpf/prog_tests/tc_redirect.c
>> +++ b/tools/testing/selftests/bpf/prog_tests/tc_redirect.c
>> @@ -890,9 +890,6 @@ static void test_udp_dtime(struct test_tc_dtime *skel, int family, bool bpf_fwd)
>>         ASSERT_EQ(dtimes[INGRESS_FWDNS_P100], 0,
>>             dtime_cnt_str(t, INGRESS_FWDNS_P100));
>> -    /* non mono delivery time is not forwarded */
>> -    ASSERT_EQ(dtimes[INGRESS_FWDNS_P101], 0,
>> -          dtime_cnt_str(t, INGRESS_FWDNS_P101));
>>       for (i = EGRESS_FWDNS_P100; i < SET_DTIME; i++)
>>           ASSERT_GT(dtimes[i], 0, dtime_cnt_str(t, i));
>>   diff --git a/tools/testing/selftests/bpf/progs/test_tc_dtime.c b/tools/testing/selftests/bpf/progs/test_tc_dtime.c
>> index 74ec09f040b7..21f5be202e4b 100644
>> --- a/tools/testing/selftests/bpf/progs/test_tc_dtime.c
>> +++ b/tools/testing/selftests/bpf/progs/test_tc_dtime.c
>> @@ -222,13 +222,19 @@ int egress_host(struct __sk_buff *skb)
>>           return TC_ACT_OK;
>>         if (skb_proto(skb_type) == IPPROTO_TCP) {
>> -        if (skb->tstamp_type == BPF_SKB_TSTAMP_DELIVERY_MONO &&
>> +        if (skb->tstamp_type == BPF_SKB_CLOCK_MONOTONIC &&
>> +            skb->tstamp)
>> +            inc_dtimes(EGRESS_ENDHOST);
>> +        else
>> +            inc_errs(EGRESS_ENDHOST);
>> +    } else if (skb_proto(skb_type) == IPPROTO_UDP) {
>> +        if (skb->tstamp_type == BPF_SKB_CLOCK_TAI &&
>>               skb->tstamp)
>>               inc_dtimes(EGRESS_ENDHOST);
>>           else
>>               inc_errs(EGRESS_ENDHOST);
>>       } else {
>> -        if (skb->tstamp_type == BPF_SKB_TSTAMP_UNSPEC &&
>> +        if (skb->tstamp_type == BPF_SKB_CLOCK_REALTIME &&
>>               skb->tstamp)
> 
> Since the UDP+TAI can be handled properly in the above "else if" case now, I would like to further tighten the bolt on detecting the non-zero REALTIME skb->tstamp here since it should not happen at egress. Something like:
> 
>     } else {
>         if (skb->tstamp_type == BPF_SKB_CLOCK_REALTIME &&
>             skb->tstamp)
>             inc_errs(EGRESS_ENDHOST);
>     }
> 
> I ran the test (w or w/o the above inc_errs changes) in a loop and it consistently passes now.
> 
> Other than the above small nits, in the next re-spin, please remove the RFC tag and you can carry my reviewed-by to all 3 patches. Thanks.
> 
Noted! 
Thank you Martin and Willem for helping me with this series. 
And all the design discussion we had throughout the series. 
Appreciate all the comments from yourside. 
I will raise the last series with no RFC tag 
1. carry Reviewed-by: 
2. Fix all the above comments 


> Reviewed-by: Martin KaFai Lau <martin.lau@kernel.org>
> 
>>               inc_dtimes(EGRESS_ENDHOST);
>>           else
>