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tcp: Extend SOF_TIMESTAMPING_RX_SOFTWARE to TCP recvmsg

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When SOF_TIMESTAMPING_RX_SOFTWARE is enabled for tcp sockets, return the
timestamp corresponding to the highest sequence number data returned.

Previously the skb->tstamp is overwritten when a TCP packet is placed
in the out of order queue.  While the packet is in the ooo queue, save the
timestamp in the TCB_SKB_CB.  This space is shared with the gso_*
options which are only used on the tx path, and a previously unused 4
byte hole.

When skbs are coalesced either in the sk_receive_queue or the
out_of_order_queue always choose the timestamp of the appended skb to
maintain the invariant of returning the timestamp of the last byte in
the recvmsg buffer.

Signed-off-by: Mike Maloney <maloney@google.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Mike Maloney
2017-08-22 17:08:48 -04:00
committed by David S. Miller
parent b28547728d
commit 98aaa913b4
5 changed files with 108 additions and 5 deletions
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9
include/net/tcp.h
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@@ -774,6 +774,12 @@ struct tcp_skb_cb {
u16 tcp_gso_segs;
u16 tcp_gso_size;
};
/* Used to stash the receive timestamp while this skb is in the
* out of order queue, as skb->tstamp is overwritten by the
* rbnode.
*/
ktime_t swtstamp;
};
__u8 tcp_flags; /* TCP header flags. (tcp[13]) */
@@ -790,7 +796,8 @@ struct tcp_skb_cb {
__u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */
__u8 txstamp_ack:1, /* Record TX timestamp for ack? */
eor:1, /* Is skb MSG_EOR marked? */
unused:6;
has_rxtstamp:1, /* SKB has a RX timestamp */
unused:5;
__u32 ack_seq; /* Sequence number ACK'd */
union {
struct {