kernel/linux.git/Documentation/networking/timestamping.txt, branch linux-4.4.y

clarify implementation of ethtool's get_ts_info op

2015-07-18T02:59:04+00:00

This patch adds some clarification about the intended way to implement both SIOCSHWTSTAMP and ethtool's get_ts_info. The HWTSTAMP API has several Rx filters which are very specific, as well as more general filters. The specific filters really only exist to support some broken hardware which can't fully implement the generic filters. This patch adds clarification that it is okay to support the specific filters in SIOCSHWTSTAMP by upscaling them to the generic filters. In addition, update the header for ethtool_ts_info to specify that drivers ought to only report the filters they support without upscaling in this manner. Signed-off-by: Jacob Keller Acked-by: Richard Cochran Tested-by: Phil Schmitt Reviewed-by: Aaron Brown Signed-off-by: Jeff Kirsher

net-timestamp: no-payload option

2015-02-03T02:46:51+00:00

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 ---- Changes (rfc -> v1) - add documentation - remove unnecessary skb->len test (thanks to Richard Cochran) Signed-off-by: David S. Miller

net-timestamp: expand documentation and test

2014-12-09T01:20:48+00:00

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 Signed-off-by: David S. Miller

net-timestamp: allow reading recv cmsg on errqueue with origin tstamp

2014-12-09T01:20:48+00:00

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 ---- 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

net-timestamp: Fix a documentation typo

2014-11-25T18:35:26+00:00

SOF_TIMESTAMPING_OPT_ID puts the id in ee_data, not ee_info. Cc: Willem de Bruijn Signed-off-by: Andy Lutomirski Acked-by: Willem de Bruijn Signed-off-by: David S. Miller

net-timestamp: expand documentation

2014-09-02T04:49:08+00:00

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 Signed-off-by: David S. Miller

net: remove deprecated syststamp timestamp

2014-07-29T18:39:50+00:00

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 Signed-off-by: David S. Miller

net-timestamp: document deprecated syststamp

2014-07-15T23:32:45+00:00

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 ---- We can consider adding a WARN_ON_ONCE in__sock_recv_timestamp if non-zero syststamp is encountered Acked-by: Richard Cochran Signed-off-by: David S. Miller

doc: update driver TX algorithm in timestamping.txt

2014-03-18T19:16:48+00:00

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 Signed-off-by: David S. Miller

net: Improve SO_TIMESTAMPING documentation and fix a minor code bug

2014-03-06T21:18:01+00:00

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 Acked-by: Richard Cochran Signed-off-by: David S. Miller