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>
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>
Add SOF_TIMESTAMPING_TX_ACK, a request for a tstamp when the last byte
in the send() call is acknowledged. It implements the feature for TCP.
The timestamp is generated when the TCP socket cumulative ACK is moved
beyond the tracked seqno for the first time. The feature ignores SACK
and FACK, because those acknowledge the specific byte, but not
necessarily the entire contents of the buffer up to that byte.
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Kernel transmit latency is often incurred in the packet scheduler.
Introduce a new timestamp on transmission just before entering the
scheduler. When data travels through multiple devices (bonding,
tunneling, ...) each device will export an individual timestamp.
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Datagrams timestamped on transmission can coexist in the kernel stack
and be reordered in packet scheduling. When reading looped datagrams
from the socket error queue it is not always possible to unique
correlate looped data with original send() call (for application
level retransmits). Even if possible, it may be expensive and complex,
requiring packet inspection.
Introduce a data-independent ID mechanism to associate timestamps with
send calls. Pass an ID alongside the timestamp in field ee_data of
sock_extended_err.
The ID is a simple 32 bit unsigned int that is associated with the
socket and incremented on each send() call for which software tx
timestamp generation is enabled.
The feature is enabled only if SOF_TIMESTAMPING_OPT_ID is set, to
avoid changing ee_data for existing applications that expect it 0.
The counter is reset each time the flag is reenabled. Reenabling
does not change the ID of already submitted data. It is possible
to receive out of order IDs if the timestamp stream is not quiesced
first.
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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>
Fix the name of the rx_filter field.
Remove text about 32/64-bit compatibility; this works just the same as
for most socket ioctls and as the structure is not allowed to grow
there is no need to remind anyone how to maintain it.
Add explanation about drivers changing the filter mode.
Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Michael Kerrisk <mtk.manpages@gmail.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Dave Jones <davej@redhat.com>
Willem de Bruijn