summaryrefslogtreecommitdiffstats
path: root/Documentation/networking/timestamping.txt
AgeCommit message (Collapse)Author
2015-02-02net-timestamp: no-payload optionWillem de Bruijn
Add timestamping option SOF_TIMESTAMPING_OPT_TSONLY. For transmit timestamps, this loops timestamps on top of empty packets. Doing so reduces the pressure on SO_RCVBUF. Payload inspection and cmsg reception (aside from timestamps) are no longer possible. This works together with a follow on patch that allows administrators to only allow tx timestamping if it does not loop payload or metadata. Signed-off-by: Willem de Bruijn <willemb@google.com> ---- Changes (rfc -> v1) - add documentation - remove unnecessary skb->len test (thanks to Richard Cochran) Signed-off-by: David S. Miller <davem@davemloft.net>
2014-12-08net-timestamp: expand documentation and testWillem de Bruijn
Documentation: expand explanation of timestamp counter Test: new: flag -I requests and prints PKTINFO new: flag -x prints payload (possibly truncated) fix: remove pretty print that breaks common flag '-l 1' Signed-off-by: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-12-08net-timestamp: allow reading recv cmsg on errqueue with origin tstampWillem de Bruijn
Allow reading of timestamps and cmsg at the same time on all relevant socket families. One use is to correlate timestamps with egress device, by asking for cmsg IP_PKTINFO. on AF_INET sockets, call the relevant function (ip_cmsg_recv). To avoid changing legacy expectations, only do so if the caller sets a new timestamping flag SOF_TIMESTAMPING_OPT_CMSG. on AF_INET6 sockets, IPV6_PKTINFO and all other recv cmsg are already returned for all origins. only change is to set ifindex, which is not initialized for all error origins. In both cases, only generate the pktinfo message if an ifindex is known. This is not the case for ACK timestamps. The difference between the protocol families is probably a historical accident as a result of the different conditions for generating cmsg in the relevant ip(v6)_recv_error function: ipv4: if (serr->ee.ee_origin == SO_EE_ORIGIN_ICMP) { ipv6: if (serr->ee.ee_origin != SO_EE_ORIGIN_LOCAL) { At one time, this was the same test bar for the ICMP/ICMP6 distinction. This is no longer true. Signed-off-by: Willem de Bruijn <willemb@google.com> ---- Changes v1 -> v2 large rewrite - integrate with existing pktinfo cmsg generation code - on ipv4: only send with new flag, to maintain legacy behavior - on ipv6: send at most a single pktinfo cmsg - on ipv6: initialize fields if not yet initialized The recv cmsg interfaces are also relevant to the discussion of whether looping packet headers is problematic. For v6, cmsgs that identify many headers are already returned. This patch expands that to v4. If it sounds reasonable, I will follow with patches 1. request timestamps without payload with SOF_TIMESTAMPING_OPT_TSONLY (http://patchwork.ozlabs.org/patch/366967/) 2. sysctl to conditionally drop all timestamps that have payload or cmsg from users without CAP_NET_RAW. Signed-off-by: David S. Miller <davem@davemloft.net>
2014-11-25net-timestamp: Fix a documentation typoAndrew Lutomirski
SOF_TIMESTAMPING_OPT_ID puts the id in ee_data, not ee_info. Cc: Willem de Bruijn <willemb@google.com> Signed-off-by: Andy Lutomirski <luto@amacapital.net> Acked-by: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-09-01net-timestamp: expand documentationWillem de Bruijn
Expand Documentation/networking/timestamping.txt with new interfaces and bytestream timestamping. Also minor cleanup of the other text. Import txtimestamp.c test of the new features. Signed-off-by: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-07-29net: remove deprecated syststamp timestampWillem de Bruijn
The SO_TIMESTAMPING API defines three types of timestamps: software, hardware in raw format (hwtstamp) and hardware converted to system format (syststamp). The last has been deprecated in favor of combining hwtstamp with a PTP clock driver. There are no active users in the kernel. The option was device driver dependent. If set, but without hardware support, the correct behavior is to return zero in the relevant field in the SCM_TIMESTAMPING ancillary message. Without device drivers implementing the option, this field is effectively always zero. Remove the internal plumbing to dissuage new drivers from implementing the feature. Keep the SOF_TIMESTAMPING_SYS_HARDWARE flag, however, to avoid breaking existing applications that request the timestamp. Signed-off-by: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-07-15net-timestamp: document deprecated syststampWillem de Bruijn
The SO_TIMESTAMPING API defines option SOF_TIMESTAMPING_SYS_HW. This feature is deprecated. It should not be implemented by new device drivers. Existing drivers do not implement it, either -- with one exception. Driver developers are encouraged to expose the NIC hw clock as a PTP HW clock source, instead, and synchronize system time to the HW source. The control flag cannot be removed due to being part of the ABI, nor can the structure scm_timestamping that is returned. Due to the one legacy driver, the internal datapath and structure are not removed. This patch only clearly marks the interface as deprecated. Device drivers should always return a syststamp value of zero. Signed-off-by: Willem de Bruijn <willemb@google.com> ---- We can consider adding a WARN_ON_ONCE in__sock_recv_timestamp if non-zero syststamp is encountered Acked-by: Richard Cochran <richardcochran@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-03-18doc: update driver TX algorithm in timestamping.txtJakub Kicinski
Since cd4d8fdad1f1 ("net: kernel panic in dev_hard_start_xmit: remove faulty software TX time stamping") dev_hard_start_xmit() will not provide software timestamps. It's a responsibility of the drivers to call skb_tx_timestamp() at the right time. Cc: linux-doc@vger.kernel.org Signed-off-by: Jakub Kicinski <kubakici@wp.pl> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-03-06net: Improve SO_TIMESTAMPING documentation and fix a minor code bugAndrew Lutomirski
The original documentation was very unclear. The code fix is presumably related to the formerly unclear documentation: SOCK_TIMESTAMPING_RX_SOFTWARE has no effect on __sock_recv_timestamp's behavior, so calling __sock_recv_ts_and_drops from sock_recv_ts_and_drops if only SOCK_TIMESTAMPING_RX_SOFTWARE is set is pointless. This should have no user-observable effect. Signed-off-by: Andy Lutomirski <luto@amacapital.net> Acked-by: Richard Cochran <richardcochran@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-11-19net_tstamp: Add SIOCGHWTSTAMP ioctl to match SIOCSHWTSTAMPBen Hutchings
SIOCSHWTSTAMP returns the real configuration to the application using it, but there is currently no way for any other application to find out the configuration non-destructively. Add a new ioctl for this, making it unprivileged. Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
2010-08-19net: simplify flags for tx timestampingOliver Hartkopp
This patch removes the abstraction introduced by the union skb_shared_tx in the shared skb data. The access of the different union elements at several places led to some confusion about accessing the shared tx_flags e.g. in skb_orphan_try(). http://marc.info/?l=linux-netdev&m=128084897415886&w=2 Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net> Signed-off-by: David S. Miller <davem@davemloft.net>
2010-04-07net: corrected documentation for hardware time stampingPatrick Loschmidt
The current documentation for hardware time stamping does not correctly specify the available kernel functions since the implementation was changed later on. Signed-off-by: Patrick Loschmidt <Patrick.Loschmidt@oeaw.ac.at> Signed-off-by: David S. Miller <davem@davemloft.net>
2009-02-15ip: support for TX timestamps on UDP and RAW socketsPatrick Ohly
Instructions for time stamping outgoing packets are take from the socket layer and later copied into the new skb. Signed-off-by: Patrick Ohly <patrick.ohly@intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2009-02-15net: new user space API for time stamping of incoming and outgoing packetsPatrick Ohly
User space can request hardware and/or software time stamping. Reporting of the result(s) via a new control message is enabled separately for each field in the message because some of the fields may require additional computation and thus cause overhead. User space can tell the different kinds of time stamps apart and choose what suits its needs. When a TX timestamp operation is requested, the TX skb will be cloned and the clone will be time stamped (in hardware or software) and added to the socket error queue of the skb, if the skb has a socket associated with it. The actual TX timestamp will reach userspace as a RX timestamp on the cloned packet. If timestamping is requested and no timestamping is done in the device driver (potentially this may use hardware timestamping), it will be done in software after the device's start_hard_xmit routine. Signed-off-by: Patrick Ohly <patrick.ohly@intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>