From: Arjun Roy <arjunroy@google.com>
To: David Ahern <dsahern@gmail.com>
Cc: Leon Romanovsky <leon@kernel.org>,
Jakub Kicinski <kuba@kernel.org>,
Arjun Roy <arjunroy.kdev@gmail.com>,
David Miller <davem@davemloft.net>,
netdev <netdev@vger.kernel.org>,
Eric Dumazet <edumazet@google.com>,
Soheil Hassas Yeganeh <soheil@google.com>
Subject: Re: [net-next v2 2/2] tcp: Add receive timestamp support for receive zerocopy.
Date: Mon, 1 Feb 2021 18:20:23 -0800 [thread overview]
Message-ID: <CAOFY-A2y20N9mUDgknbqM=tR0SA6aS6aTjyybggWNa8uY2=U_Q@mail.gmail.com> (raw)
In-Reply-To: <ad3d4a29-b6c1-c6d2-3c0f-fff212f23311@gmail.com>
On Mon, Feb 1, 2021 at 6:06 PM David Ahern <dsahern@gmail.com> wrote:
>
> On 1/24/21 11:15 PM, Leon Romanovsky wrote:
> > On Fri, Jan 22, 2021 at 10:55:45PM -0700, David Ahern wrote:
> >> On 1/22/21 9:07 PM, Jakub Kicinski wrote:
> >>> On Wed, 20 Jan 2021 16:41:48 -0800 Arjun Roy wrote:
> >>>> diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h
> >>>> index 768e93bd5b51..b216270105af 100644
> >>>> --- a/include/uapi/linux/tcp.h
> >>>> +++ b/include/uapi/linux/tcp.h
> >>>> @@ -353,5 +353,9 @@ struct tcp_zerocopy_receive {
> >>>> __u64 copybuf_address; /* in: copybuf address (small reads) */
> >>>> __s32 copybuf_len; /* in/out: copybuf bytes avail/used or error */
> >>>> __u32 flags; /* in: flags */
> >>>> + __u64 msg_control; /* ancillary data */
> >>>> + __u64 msg_controllen;
> >>>> + __u32 msg_flags;
> >>>> + /* __u32 hole; Next we must add >1 u32 otherwise length checks fail. */
> >>>
> >>> Well, let's hope nobody steps on this landmine.. :)
> >>>
> >>
> >> Past suggestions were made to use anonymous declarations - e.g., __u32
> >> :32; - as a way of reserving the space for future use. That or declare
> >> '__u32 resvd', check that it must be 0 and makes it available for later
> >> (either directly or with a union).
> >
> > This is the schema (reserved field without union) used by the RDMA UAPIs from
> > the beginning (>20 years already) and it works like a charm.
> >
> > Highly recommend :).
> >
>
> agreed.
>
> Arjun: would you mind following up with a patch to make this hole
> explicit and usable for the next extension? Thanks,
Will do.
-Arjun
next prev parent reply other threads:[~2021-02-02 2:21 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-21 0:41 [net-next v2 0/2] tcp: add CMSG+rx timestamps to rx. zerocopy Arjun Roy
2021-01-21 0:41 ` [net-next v2 1/2] tcp: Remove CMSG magic numbers for tcp_recvmsg() Arjun Roy
2021-01-21 0:41 ` [net-next v2 2/2] tcp: Add receive timestamp support for receive zerocopy Arjun Roy
2021-01-23 4:07 ` Jakub Kicinski
2021-01-23 5:55 ` David Ahern
2021-01-25 6:15 ` Leon Romanovsky
2021-02-02 2:06 ` David Ahern
2021-02-02 2:20 ` Arjun Roy [this message]
2021-02-02 6:52 ` Leon Romanovsky
2021-02-04 23:03 ` Arjun Roy
2021-02-05 0:00 ` Jakub Kicinski
2021-02-05 1:32 ` Arjun Roy
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