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Subject: Re: [PATCH net-next v3] Revert "net: Re-use and set
 mono_delivery_time bit for userspace tstamp packets"
To: Abhishek Chauhan <quic_abchauha@quicinc.com>,
 "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>,
 Martin KaFai Lau <martin.lau@linux.dev>
Cc: kernel@quicinc.com, bpf@vger.kernel.org
References: <20240314192404.1867189-1-quic_abchauha@quicinc.com>
From: Daniel Borkmann <daniel@iogearbox.net>
Message-ID: <695f3ef3-7b30-7806-60d0-bd3d27130361@iogearbox.net>
Date: Thu, 14 Mar 2024 22:14:01 +0100
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On 3/14/24 8:24 PM, Abhishek Chauhan wrote:
> This reverts commit 885c36e59f46375c138de18ff1692f18eff67b7f.
> 
> The patch currently broke the bpf selftest test_tc_dtime because
> uapi field __sk_buff->tstamp_type depends on skb->mono_delivery_time which
> does not necessarily mean mono with the original fix as the bit was re-used
> for userspace timestamp as well to avoid tstamp reset in the forwarding
> path. To solve this we need to keep mono_delivery_time as is and
> introduce another bit called user_delivery_time and fall back to the
> initial proposal of setting the user_delivery_time bit based on
> sk_clockid set from userspace.
> 
> Fixes: 885c36e59f46 ("net: Re-use and set mono_delivery_time bit for userspace tstamp packets")
> Link: https://lore.kernel.org/netdev/bc037db4-58bb-4861-ac31-a361a93841d3@linux.dev/
> Signed-off-by: Abhishek Chauhan <quic_abchauha@quicinc.com>

[ Side note: target tree for this fix is net not net-next, the follow-up
   work would be net-next then. ]

Acked-by: Daniel Borkmann <daniel@iogearbox.net>