linux-toradex.git/include/uapi/linux/tcp.h, branch v5.1-rc1

tcp: add SRTT to SCM_TIMESTAMPING_OPT_STATS

2018-11-18T04:34:36+00:00

Add TCP_NLA_SRTT to SCM_TIMESTAMPING_OPT_STATS that reports the smoothed
round trip time in microseconds (tcp_sock.srtt_us >> 3).

Signed-off-by: Yousuk Seung 
Signed-off-by: Eric Dumazet 
Acked-by: Soheil Hassas Yeganeh 
Acked-by: Neal Cardwell 
Acked-by: Yuchung Cheng 
Signed-off-by: David S. Miller

tcp: add stat of data packet reordering events

2018-08-01T16:56:10+00:00

Introduce a new TCP stats to record the number of reordering events seen
and expose it in both tcp_info (TCP_INFO) and opt_stats
(SOF_TIMESTAMPING_OPT_STATS).
Application can use this stats to track the frequency of the reordering
events in addition to the existing reordering stats which tracks the
magnitude of the latest reordering event.

Note: this new stats tracks reordering events triggered by ACKs, which
could often be fewer than the actual number of packets being delivered
out-of-order.

Signed-off-by: Wei Wang 
Signed-off-by: Eric Dumazet 
Acked-by: Neal Cardwell 
Acked-by: Soheil Hassas Yeganeh 
Acked-by: Yuchung Cheng 
Signed-off-by: David S. Miller

tcp: add dsack blocks received stats

2018-08-01T16:56:10+00:00

Introduce a new TCP stat to record the number of DSACK blocks received
(RFC4989 tcpEStatsStackDSACKDups) and expose it in both tcp_info
(TCP_INFO) and opt_stats (SOF_TIMESTAMPING_OPT_STATS).

Signed-off-by: Wei Wang 
Signed-off-by: Eric Dumazet 
Acked-by: Neal Cardwell 
Acked-by: Soheil Hassas Yeganeh 
Acked-by: Yuchung Cheng 
Signed-off-by: David S. Miller

tcp: add data bytes retransmitted stats

2018-08-01T16:56:10+00:00

Introduce a new TCP stat to record the number of bytes retransmitted
(RFC4898 tcpEStatsPerfOctetsRetrans) and expose it in both tcp_info
(TCP_INFO) and opt_stats (SOF_TIMESTAMPING_OPT_STATS).

Signed-off-by: Wei Wang 
Signed-off-by: Eric Dumazet 
Acked-by: Neal Cardwell 
Acked-by: Soheil Hassas Yeganeh 
Acked-by: Yuchung Cheng 
Signed-off-by: David S. Miller

tcp: add data bytes sent stats

2018-08-01T16:56:10+00:00

Introduce a new TCP stat to record the number of bytes sent
(RFC4898 tcpEStatsPerfHCDataOctetsOut) and expose it in both tcp_info
(TCP_INFO) and opt_stats (SOF_TIMESTAMPING_OPT_STATS).

Signed-off-by: Wei Wang 
Signed-off-by: Eric Dumazet 
Acked-by: Neal Cardwell 
Acked-by: Soheil Hassas Yeganeh 
Acked-by: Yuchung Cheng 
Signed-off-by: David S. Miller

tcp: Fix broken repair socket window probe patch

2018-07-16T21:06:44+00:00

Correct previous bad attempt at allowing sockets to come out of TCP
repair without sending window probes. To avoid changing size of
the repair variable in struct tcp_sock, this lets the decision for
sending probes or not to be made when coming out of repair by
introducing two ways to turn it off.

v2:
* Remove erroneous comment; defines now make behavior clear

Fixes: 70b7ff130224 ("tcp: allow user to create repair socket without window probes")
Signed-off-by: Stefan Baranoff 
Signed-off-by: Eric Dumazet 
Acked-by: Andrei Vagin 
Signed-off-by: David S. Miller

tcp: send in-queue bytes in cmsg upon read

2018-05-01T22:56:29+00:00

Applications with many concurrent connections, high variance
in receive queue length and tight memory bounds cannot
allocate worst-case buffer size to drain sockets. Knowing
the size of receive queue length, applications can optimize
how they allocate buffers to read from the socket.

The number of bytes pending on the socket is directly
available through ioctl(FIONREAD/SIOCINQ) and can be
approximated using getsockopt(MEMINFO) (rmem_alloc includes
skb overheads in addition to application data). But, both of
these options add an extra syscall per recvmsg. Moreover,
ioctl(FIONREAD/SIOCINQ) takes the socket lock.

Add the TCP_INQ socket option to TCP. When this socket
option is set, recvmsg() relays the number of bytes available
on the socket for reading to the application via the
TCP_CM_INQ control message.

Calculate the number of bytes after releasing the socket lock
to include the processed backlog, if any. To avoid an extra
branch in the hot path of recvmsg() for this new control
message, move all cmsg processing inside an existing branch for
processing receive timestamps. Since the socket lock is not held
when calculating the size of receive queue, TCP_INQ is a hint.
For example, it can overestimate the queue size by one byte,
if FIN is received.

With this method, applications can start reading from the socket
using a small buffer, and then use larger buffers based on the
remaining data when needed.

V3 change-log:
	As suggested by David Miller, added loads with barrier
	to check whether we have multiple threads calling recvmsg
	in parallel. When that happens we lock the socket to
	calculate inq.
V4 change-log:
	Removed inline from a static function.

Signed-off-by: Soheil Hassas Yeganeh 
Signed-off-by: Yuchung Cheng 
Signed-off-by: Willem de Bruijn 
Reviewed-by: Eric Dumazet 
Reviewed-by: Neal Cardwell 
Suggested-by: David Miller 
Signed-off-by: David S. Miller

tcp: add TCP_ZEROCOPY_RECEIVE support for zerocopy receive

2018-04-30T01:29:55+00:00

When adding tcp mmap() implementation, I forgot that socket lock
had to be taken before current->mm->mmap_sem. syzbot eventually caught
the bug.

Since we can not lock the socket in tcp mmap() handler we have to
split the operation in two phases.

1) mmap() on a tcp socket simply reserves VMA space, and nothing else.
  This operation does not involve any TCP locking.

2) getsockopt(fd, IPPROTO_TCP, TCP_ZEROCOPY_RECEIVE, ...) implements
 the transfert of pages from skbs to one VMA.
  This operation only uses down_read(¤t->mm->mmap_sem) after
  holding TCP lock, thus solving the lockdep issue.

This new implementation was suggested by Andy Lutomirski with great details.

Benefits are :

- Better scalability, in case multiple threads reuse VMAS
   (without mmap()/munmap() calls) since mmap_sem wont be write locked.

- Better error recovery.
   The previous mmap() model had to provide the expected size of the
   mapping. If for some reason one part could not be mapped (partial MSS),
   the whole operation had to be aborted.
   With the tcp_zerocopy_receive struct, kernel can report how
   many bytes were successfuly mapped, and how many bytes should
   be read to skip the problematic sequence.

- No more memory allocation to hold an array of page pointers.
  16 MB mappings needed 32 KB for this array, potentially using vmalloc() :/

- skbs are freed while mmap_sem has been released

Following patch makes the change in tcp_mmap tool to demonstrate
one possible use of mmap() and setsockopt(... TCP_ZEROCOPY_RECEIVE ...)

Note that memcg might require additional changes.

Fixes: 93ab6cc69162 ("tcp: implement mmap() for zero copy receive")
Signed-off-by: Eric Dumazet 
Reported-by: syzbot 
Suggested-by: Andy Lutomirski 
Cc: linux-mm@kvack.org
Acked-by: Soheil Hassas Yeganeh 
Signed-off-by: David S. Miller

tcp: export packets delivery info

2018-04-19T17:05:16+00:00

Export data delivered and delivered with CE marks to
1) SNMP TCPDelivered and TCPDeliveredCE
2) getsockopt(TCP_INFO)
3) Timestamping API SOF_TIMESTAMPING_OPT_STATS

Note that for SCM_TSTAMP_ACK, the delivery info in
SOF_TIMESTAMPING_OPT_STATS is reported before the info
was fully updated on the ACK.

These stats help application monitor TCP delivery and ECN status
on per host, per connection, even per message level.

Signed-off-by: Yuchung Cheng 
Reviewed-by: Neal Cardwell 
Reviewed-by: Soheil Hassas Yeganeh 
Reviewed-by: Eric Dumazet 
Signed-off-by: David S. Miller

tcp: add snd_ssthresh stat in SCM_TIMESTAMPING_OPT_STATS

2018-03-16T19:07:48+00:00

This patch adds TCP_NLA_SND_SSTHRESH stat into SCM_TIMESTAMPING_OPT_STATS
that reports tcp_sock.snd_ssthresh.

Signed-off-by: Yousuk Seung 
Signed-off-by: Neal Cardwell 
Signed-off-by: Priyaranjan Jha 
Signed-off-by: Soheil Hassas Yeganeh 
Signed-off-by: Yuchung Cheng 
Reviewed-by: Eric Dumazet 
Signed-off-by: David S. Miller