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SubjectRe: [PATCH 7/8] socket: Add SO_TIMESTAMP[NS]_NEW
On Sat, Nov 24, 2018 at 10:59 PM Willem de Bruijn
<willemdebruijn.kernel@gmail.com> wrote:
>
> On Sat, Nov 24, 2018 at 3:58 AM Deepa Dinamani <deepa.kernel@gmail.com> wrote:
> >
> > Add SO_TIMESTAMP_NEW and SO_TIMESTAMPNS_NEW variants of
> > socket timestamp options.
> > These are the y2038 safe versions of the SO_TIMESTAMP_OLD
> > and SO_TIMESTAMPNS_OLD for all architectures.
> >
> > Note that the format of scm_timestamping.ts[0] is not changed
> > in this patch.
> >
> > Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
> > Cc: jejb@parisc-linux.org
> > Cc: ralf@linux-mips.org
> > Cc: rth@twiddle.net
> > Cc: linux-alpha@vger.kernel.org
> > Cc: linux-mips@linux-mips.org
> > Cc: linux-parisc@vger.kernel.org
> > Cc: linux-rdma@vger.kernel.org
> > Cc: netdev@vger.kernel.org
> > Cc: sparclinux@vger.kernel.org
> > ---
>
> > diff --git a/include/net/sock.h b/include/net/sock.h
> > index 8143c4c1a49d..9edf909dc176 100644
> > --- a/include/net/sock.h
> > +++ b/include/net/sock.h
> > @@ -801,6 +801,7 @@ enum sock_flags {
> > SOCK_RCU_FREE, /* wait rcu grace period in sk_destruct() */
> > SOCK_TXTIME,
> > SOCK_XDP, /* XDP is attached */
> > + SOCK_TSTAMP_NEW, /* Indicates 64 bit timestamps always */
>
> sk_flags is getting exhausted. Commit b9f40e21ef42 ("net-timestamp:
> move timestamp flags out of sk_flags") added a new u16 sk_tsflags
> specifically for timestamps. That may be a better choice here, too.
>
> > diff --git a/net/core/sock.c b/net/core/sock.c
> > index e60036618205..7b485dfaa400 100644
> > --- a/net/core/sock.c
> > +++ b/net/core/sock.c
> > @@ -652,15 +652,23 @@ static void setsockopt_timestamp(struct sock *sk, int type, int val)
> > if (!val) {
> > sock_reset_flag(sk, SOCK_RCVTSTAMP);
> > sock_reset_flag(sk, SOCK_RCVTSTAMPNS);
> > + sock_reset_flag(sk, SOCK_TSTAMP_NEW);
> > return;
> > }
> >
> > + if (type == SO_TIMESTAMP_NEW || type == SO_TIMESTAMPNS_NEW)
> > + sock_set_flag(sk, SOCK_TSTAMP_NEW);
> > + else
> > + sock_reset_flag(sk, SOCK_TSTAMP_NEW);
> > +
>
> if adding a boolean whether the socket uses new or old-style
> timestamps, perhaps fail hard if a process tries to set a new-style
> option while an old-style is already set and vice versa. Also include
> SO_TIMESTAMPING_NEW as it toggles the same option.
>
> > diff --git a/net/socket.c b/net/socket.c
> > index d3defba55547..9abeb6bc9cfe 100644
> > --- a/net/socket.c
> > +++ b/net/socket.c
> > @@ -699,6 +699,38 @@ static void put_ts_pktinfo(struct msghdr *msg, struct sk_buff *skb)
> > sizeof(ts_pktinfo), &ts_pktinfo);
> > }
> >
> > +static void sock_recv_sw_timestamp(struct msghdr *msg, struct sock *sk,
> > + struct sk_buff *skb)
> > +{
> > + if (sock_flag(sk, SOCK_TSTAMP_NEW)) {
> > + if (!sock_flag(sk, SOCK_RCVTSTAMPNS)) {
> > + struct sock_timeval tv;
> > +
> > + skb_get_new_timestamp(skb, &tv);
> > + put_cmsg(msg, SOL_SOCKET, SO_TIMESTAMP_NEW,
> > + sizeof(tv), &tv);
> > + } else {
> > + struct __kernel_timespec ts;
> > +
> > + skb_get_new_timestampns(skb, &ts);
> > + put_cmsg(msg, SOL_SOCKET, SO_TIMESTAMPNS_NEW,
> > + sizeof(ts), &ts);
> > + }
> > + }
> > + if (!sock_flag(sk, SOCK_RCVTSTAMPNS)) {
> > + struct __kernel_old_timeval tv;
> > +
> > + skb_get_timestamp(skb, &tv);
> > + put_cmsg(msg, SOL_SOCKET, SO_TIMESTAMP_OLD,
> > + sizeof(tv), &tv);
> > + } else {
> > + struct timespec ts;
> > +
> > + skb_get_timestampns(skb, &ts);
> > + put_cmsg(msg, SOL_SOCKET, SO_TIMESTAMPNS_OLD,
> > + sizeof(ts), &ts);
> > + }
> > +}
> > /*
> > * called from sock_recv_timestamp() if sock_flag(sk, SOCK_RCVTSTAMP)
> > * or sock_flag(sk, SOCK_RCVTSTAMPNS)
> > @@ -719,19 +751,8 @@ void __sock_recv_timestamp(struct msghdr *msg, struct sock *sk,
> > false_tstamp = 1;
> > }
> > - if (need_software_tstamp) {
>
> Considerably less code churn if adding __sock_recv_timestamp_2038 and
> calling that here:
>
> if (sock_flag(sk, SOCK_TSTAMP_NEW))
> __sock_recv_timestamp_2038(msg, sk, skb);
> else if ...
>
> Same for the tcp case above, really, and in the case of the next patch
> for SO_TIMESTAMPING_NEW

That naming convention, ..._2038, is not the nicest, of course. That
is not the relevant bit in the above comment.

Come to think of it, and related to my question in patch 2 why the
need to rename at all, could all new structs, constants and functions
be named consistently with 64 suffix? __sock_recv_timestamp64,
SO_TIMESTAMPING64 and timeval64 (instead of sock_timeval,
it isn't really a sock specific struct)?

I guess that there is a good reason for the renaming exercise and
conditional mapping of SO_TIMESTAMP onto old or new interface.
Please elucidate in the commit message.

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