Lines Matching +full:send +full:- +full:empty
1 .. SPDX-License-Identifier: GPL-2.0
43 -------------------------------------------------------------
59 -------------------------------------------------------------------
72 ----------------------------------------------------------------------
95 (e.g., for sampling) by embedding an send() call within two setsockopt
127 timestamp taken immediately before send() from this timestamp. On
135 Request tx timestamps when all data in the send buffer has been
138 over-report measurement, because the timestamp is generated when all
139 data up to and including the buffer at send() was acknowledged: the
175 queue out of order from the original send() calls. It is not always
176 possible to uniquely match timestamps to the original send() calls
179 This option associates each packet at send() with a unique
181 is derived from a per-socket u32 counter (that wraps). For datagram
208 a timestamp with counter N-1. SOF_TIMESTAMPING_OPT_ID_TCP
238 timestamp as a cmsg alongside an empty packet, as opposed to
258 received the packet and its length at layer 2. A valid (non-zero)
283 ignore the unexpected non-zero value. But it makes behavior subtly
310 cmsg->cmsg_level = SOL_SOCKET;
311 cmsg->cmsg_type = SO_TIMESTAMPING;
312 cmsg->cmsg_len = CMSG_LEN(sizeof(__u32));
330 -------------------------
340 correlating a timestamp with data is non-trivial. A range of bytes
343 independent send() calls). Segments can be reordered and the same
367 individual last byte passed to send(), even if it is no longer the
369 relevant sequence number in skb_shinfo(skb)->tskey. Because an skbuff
375 send time with the value returned for each timestamp. It can prevent
378 autocork. After linux-4.7, a better way to prevent coalescing is
400 ----------------------------
423 feature. At least one field is non-zero at any time. Most timestamps
430 as linuxptp. For the PTP clock API, see Documentation/driver-api/ptp.rst.
442 socket's error queue with the send timestamp(s) attached. A process
467 is the first if ts[2] is non-zero, the second otherwise, in which
495 Reading from the error queue is always a non-blocking operation. To
531 the requested fine-grained filtering for incoming packets is not
558 /* possible values for hwtstamp_config->tx_type */
576 /* possible values for hwtstamp_config->rx_filter */
596 --------------------------------------------------------
616 - In hard_start_xmit(), check if (skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP)
617 is set no-zero. If yes, then the driver is expected to do hardware time
619 - If this is possible for the skb and requested, then declare
621 SKBTX_IN_PROGRESS in skb_shinfo(skb)->tx_flags , e.g. with::
623 skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS;
629 - Driver should call skb_tx_timestamp() as close to passing sk_buff to hardware
632 - As soon as the driver has sent the packet and/or obtained a
644 ----------------------------------------------------------
685 - ``.port_txtstamp()``: a hook called prior to the transmission of
687 This is required for two-step timestamping, since the hardware
690 packet so that it can re-enqueue the packet back into the socket's
693 in skb->cb and enqueue a tx skb queue. Typically, a switch will have a
696 key-value pairs of PTP sequence ID/message type/domain number and the
704 One-step TX timestamping do not require packet cloning, since there is
705 no follow-up message required by the PTP protocol (because the
708 to be re-enqueued into its socket's error queue.
710 - ``.port_rxtstamp()``: On RX, the BPF classifier is run by DSA to
715 timestamps might either be available in-band (through metadata in the
716 DSA header, or attached in other ways to the packet), or out-of-band
732 mii_timestamper`` and add a pointer to it in ``phydev->mii_ts``. The presence
740 - Checking, in ``.ndo_eth_ioctl``, whether ``phy_has_hwtstamp(netdev->phydev)``
744 - On RX, special intervention may or may not be needed, depending on the
747 ``skb_defer_rx_timestamp(skb)`` is necessary or not - and if it is, don't
749 enabled, and ``skb->dev->phydev->mii_ts`` exists, its ``.rxtstamp()`` hook
752 responsibility of the PHY driver to send the packet up the stack when the
760 - On TX, again, special intervention might or might not be needed. The
761 function that calls the ``mii_ts->txtstamp()`` hook is named
782 Stacked PHCs, especially DSA (but not only) - since that doesn't require any
784 all possible code paths - is that they uncover bugs which were impossible to
788 skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS;
799 the ``.ndo_eth_ioctl`` ("``priv->hwtstamp_tx_enabled == true``") and the
800 current skb requires a TX timestamp ("``skb_shinfo(skb)->tx_flags &
802 "``skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS``" flag. Note: as
810 "``skb_shinfo(skb)->tx_flags & SKBTX_IN_PROGRESS``" was set. With a stacked
817 "``skb_shinfo(skb)->tx_flags & SKBTX_IN_PROGRESS``", but also for
818 "``priv->hwtstamp_tx_enabled == true``". Because the rest of the system ensures