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Date: Thu, 9 May 2024 12:24:36 -0700
From: "Abhishek Chauhan (ABC)" <quic_abchauha@...cinc.com>
To: Martin KaFai Lau <martin.lau@...ux.dev>
CC: "David S. Miller" <davem@...emloft.net>,
Eric Dumazet
<edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni
<pabeni@...hat.com>, <netdev@...r.kernel.org>,
<linux-kernel@...r.kernel.org>, Andrew Halaney <ahalaney@...hat.com>,
"Willem
de Bruijn" <willemdebruijn.kernel@...il.com>,
Martin KaFai Lau
<martin.lau@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>, bpf
<bpf@...r.kernel.org>,
<kernel@...cinc.com>
Subject: Re: [RFC PATCH bpf-next v7 3/3] selftests/bpf: Handle forwarding of
UDP CLOCK_TAI packets
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@...cinc.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@...nel.org>
>
>> inc_dtimes(EGRESS_ENDHOST);
>> else
>
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