[NET]: Adding SO_TIMESTAMPNS / SCM_TIMESTAMPNS support

Now that network timestamps use ktime_t infrastructure, we can add a new
SOL_SOCKET sockopt  SO_TIMESTAMPNS.

This command is similar to SO_TIMESTAMP, but permits transmission of
a 'timespec struct' instead of a 'timeval struct' control message.
(nanosecond resolution instead of microsecond)

Control message is labelled SCM_TIMESTAMPNS instead of SCM_TIMESTAMP

A socket cannot mix SO_TIMESTAMP and SO_TIMESTAMPNS : the two modes are
mutually exclusive.

sock_recv_timestamp() became too big to be fully inlined so I added a
__sock_recv_timestamp() helper function.

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
CC: linux-arch@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 52 insertions, 3 deletions

diff --git a/net/compat.c b/net/compat.c
index 0e407563ae85..9a0f5f2b90c8 100644
--- a/net/compat.c
+++ b/net/compat.c
@@ -215,6 +215,7 @@ Efault:
 int put_cmsg_compat(struct msghdr *kmsg, int level, int type, int len, void *data)
 {
         struct compat_timeval ctv;
+        struct compat_timespec cts;
         struct compat_cmsghdr __user *cm = (struct compat_cmsghdr __user *) kmsg->msg_control;
         struct compat_cmsghdr cmhdr;
         int cmlen;
@@ -229,7 +230,14 @@ int put_cmsg_compat(struct msghdr *kmsg, int level, int type, int len, void *dat
                 ctv.tv_sec = tv->tv_sec;
                 ctv.tv_usec = tv->tv_usec;
                 data = &ctv;
-                len = sizeof(struct compat_timeval);
+                len = sizeof(ctv);
+        }
+        if (level == SOL_SOCKET && type == SO_TIMESTAMPNS) {
+                struct timespec *ts = (struct timespec *)data;
+                cts.tv_sec = ts->tv_sec;
+                cts.tv_nsec = ts->tv_nsec;
+                data = &cts;
+                len = sizeof(cts);
         }
 
         cmlen = CMSG_COMPAT_LEN(len);
diff --git a/net/core/sock.c b/net/core/sock.c
index 792ae39804a2..f9e6991d3729 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -521,11 +521,18 @@ set_rcvbuf:
                 break;
 
         case SO_TIMESTAMP:
+        case SO_TIMESTAMPNS:
                 if (valbool)  {
+                        if (optname == SO_TIMESTAMP)
+                                sock_reset_flag(sk, SOCK_RCVTSTAMPNS);
+                        else
+                                sock_set_flag(sk, SOCK_RCVTSTAMPNS);
                         sock_set_flag(sk, SOCK_RCVTSTAMP);
                         sock_enable_timestamp(sk);
-                } else
+                } else {
                         sock_reset_flag(sk, SOCK_RCVTSTAMP);
+                        sock_reset_flag(sk, SOCK_RCVTSTAMPNS);
+                }
                 break;
 
         case SO_RCVLOWAT:
@@ -715,7 +722,12 @@ int sock_getsockopt(struct socket *sock, int level, int optname,
                 break;
 
         case SO_TIMESTAMP:
-                v.val = sock_flag(sk, SOCK_RCVTSTAMP);
+                v.val = sock_flag(sk, SOCK_RCVTSTAMP) &&
+                                !sock_flag(sk, SOCK_RCVTSTAMPNS);
+                break;
+
+        case SO_TIMESTAMPNS:
+                v.val = sock_flag(sk, SOCK_RCVTSTAMPNS);
                 break;
 
         case SO_RCVTIMEO:
diff --git a/net/socket.c b/net/socket.c
index cf18c5eb592e..a7bd0df115b2 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -585,6 +585,35 @@ int kernel_sendmsg(struct socket *sock, struct msghdr *msg,
         return result;
 }
 
+/*
+ * called from sock_recv_timestamp() if sock_flag(sk, SOCK_RCVTSTAMP)
+ */
+void __sock_recv_timestamp(struct msghdr *msg, struct sock *sk,
+        struct sk_buff *skb)
+{
+        ktime_t kt = skb->tstamp;
+
+        if (!sock_flag(sk, SOCK_RCVTSTAMPNS)) {
+                struct timeval tv;
+                /* Race occurred between timestamp enabling and packet
+                   receiving.  Fill in the current time for now. */
+                if (kt.tv64 == 0)
+                        kt = ktime_get_real();
+                skb->tstamp = kt;
+                tv = ktime_to_timeval(kt);
+                put_cmsg(msg, SOL_SOCKET, SCM_TIMESTAMP, sizeof(tv), &tv);
+        } else {
+                struct timespec ts;
+                /* Race occurred between timestamp enabling and packet
+                   receiving.  Fill in the current time for now. */
+                if (kt.tv64 == 0)
+                        kt = ktime_get_real();
+                skb->tstamp = kt;
+                ts = ktime_to_timespec(kt);
+                put_cmsg(msg, SOL_SOCKET, SCM_TIMESTAMPNS, sizeof(ts), &ts);
+        }
+}
+
 static inline int __sock_recvmsg(struct kiocb *iocb, struct socket *sock,
                                  struct msghdr *msg, size_t size, int flags)
 {