tun: fix transmit timestamp support
Instead of using sock_tx_timestamp, use skb_tx_timestamp to record software transmit timestamp of a packet. sock_tx_timestamp resets and overrides the tx_flags of the skb. The function is intended to be called from within the protocol layer when creating the skb, not from a device driver. This is inconsistent with other drivers and will cause issues for TCP. In TCP, we intend to sample the timestamps for the last byte for each sendmsg/sendpage. For that reason, tcp_sendmsg calls tcp_tx_timestamp only with the last skb that it generates. For example, if a 128KB message is split into two 64KB packets we want to sample the SND timestamp of the last packet. The current code in the tun driver, however, will result in sampling the SND timestamp for both packets. Also, when the last packet is split into smaller packets for retranmission (see tcp_fragment), the tun driver will record timestamps for all of the retransmitted packets and not only the last packet. Fixes: eda29772 (tun: Support software transmit time stamping.) Signed-off-by: NSoheil Hassas Yeganeh <soheil@google.com> Signed-off-by: NFrancis Yan <francisyyan@google.com> Acked-by: NEric Dumazet <edumazet@google.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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