On Sat, Nov 24, 2018 at 10:59 PM Willem de Bruijn
[off-list ref] wrote:

On Sat, Nov 24, 2018 at 3:58 AM Deepa Dinamani [off-list ref] wrote:

quoted

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 <redacted>
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
---

quoted

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.

quoted

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.

quoted

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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