sock: enable timestamping using control messages

Currently, SOL_TIMESTAMPING can only be enabled using setsockopt.
This is very costly when users want to sample writes to gather
tx timestamps.

Add support for enabling SO_TIMESTAMPING via control messages by
using tsflags added in `struct sockcm_cookie` (added in the previous
patches in this series) to set the tx_flags of the last skb created in
a sendmsg. With this patch, the timestamp recording bits in tx_flags
of the skbuff is overridden if SO_TIMESTAMPING is passed in a cmsg.

Please note that this is only effective for overriding the recording
timestamps flags. Users should enable timestamp reporting (e.g.,
SOF_TIMESTAMPING_SOFTWARE | SOF_TIMESTAMPING_OPT_ID) using
socket options and then should ask for SOF_TIMESTAMPING_TX_*
using control messages per sendmsg to sample timestamps for each
write.

Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 5 deletions

diff --git a/net/socket.c b/net/socket.c
index 5f77a8e93830..979d3146b081 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -587,20 +587,20 @@ void sock_release(struct socket *sock)
 }
 EXPORT_SYMBOL(sock_release);
 
-void __sock_tx_timestamp(const struct sock *sk, __u8 *tx_flags)
+void __sock_tx_timestamp(__u16 tsflags, __u8 *tx_flags)
 {
         u8 flags = *tx_flags;
 
-        if (sk->sk_tsflags & SOF_TIMESTAMPING_TX_HARDWARE)
+        if (tsflags & SOF_TIMESTAMPING_TX_HARDWARE)
                 flags |= SKBTX_HW_TSTAMP;
 
-        if (sk->sk_tsflags & SOF_TIMESTAMPING_TX_SOFTWARE)
+        if (tsflags & SOF_TIMESTAMPING_TX_SOFTWARE)
                 flags |= SKBTX_SW_TSTAMP;
 
-        if (sk->sk_tsflags & SOF_TIMESTAMPING_TX_SCHED)
+        if (tsflags & SOF_TIMESTAMPING_TX_SCHED)
                 flags |= SKBTX_SCHED_TSTAMP;
 
-        if (sk->sk_tsflags & SOF_TIMESTAMPING_TX_ACK)
+        if (tsflags & SOF_TIMESTAMPING_TX_ACK)
                 flags |= SKBTX_ACK_TSTAMP;
 
         *tx_flags = flags;