linux-toradex.git/Documentation/networking, branch v3.4.110

pktgen: document ability to add same device to several threads

2015-10-22T01:20:02+00:00

commit 2a1ddf27e8189e1d68336c55dd2f305b224ae8f1 upstream.

The pktgen.txt documentation still claimed that adding same device to
multiple threads were not supported, but it have been since 2008 via
commit e6fce5b916cd7 ("pktgen: multiqueue etc.").

Document this and describe the naming scheme dev@X, as the procfile name
still need to be unique.

Fixes: e6fce5b916cd7 ("pktgen: multiqueue etc.")
Signed-off-by: Jesper Dangaard Brouer 
Acked-by: Alexei Starovoitov 
Signed-off-by: David S. Miller 
Signed-off-by: Zefan Li

RDS: Documentation: Document AF_RDS, PF_RDS and SOL_RDS correctly.

2015-09-18T01:20:27+00:00

commit ebe96e641dee2cbd135ee802ae7e40c361640088 upstream.

AF_RDS, PF_RDS and SOL_RDS are available in header files,
and there is no need to get their values from /proc. Document
this correctly.

Fixes: 0c5f9b8830aa ("RDS: Documentation")

Signed-off-by: Sowmini Varadhan 
Signed-off-by: David S. Miller 
Signed-off-by: Zefan Li

tcp: implement RFC 5961 3.2

2013-01-11T17:07:14+00:00

[ Upstream commit 282f23c6ee343126156dd41218b22ece96d747e3 ]

Implement the RFC 5691 mitigation against Blind
Reset attack using RST bit.

Idea is to validate incoming RST sequence,
to match RCV.NXT value, instead of previouly accepted
window : (RCV.NXT <= SEG.SEQ < RCV.NXT+RCV.WND)

If sequence is in window but not an exact match, send
a "challenge ACK", so that the other part can resend an
RST with the appropriate sequence.

Add a new sysctl, tcp_challenge_ack_limit, to limit
number of challenge ACK sent per second.

Add a new SNMP counter to count number of challenge acks sent.
(netstat -s | grep TCPChallengeACK)

Signed-off-by: Eric Dumazet 
Cc: Kiran Kumar Kella 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

tcp: change tcp_adv_win_scale and tcp_rmem[2]

2012-05-03T01:08:58+00:00

tcp_adv_win_scale default value is 2, meaning we expect a good citizen
skb to have skb->len / skb->truesize ratio of 75% (3/4)

In 2.6 kernels we (mis)accounted for typical MSS=1460 frame :
1536 + 64 + 256 = 1856 'estimated truesize', and 1856 * 3/4 = 1392.
So these skbs were considered as not bloated.

With recent truesize fixes, a typical MSS=1460 frame truesize is now the
more precise :
2048 + 256 = 2304. But 2304 * 3/4 = 1728.
So these skb are not good citizen anymore, because 1460 < 1728

(GRO can escape this problem because it build skbs with a too low
truesize.)

This also means tcp advertises a too optimistic window for a given
allocated rcvspace : When receiving frames, sk_rmem_alloc can hit
sk_rcvbuf limit and we call tcp_prune_queue()/tcp_collapse() too often,
especially when application is slow to drain its receive queue or in
case of losses (netperf is fast, scp is slow). This is a major latency
source.

We should adjust the len/truesize ratio to 50% instead of 75%

This patch :

1) changes tcp_adv_win_scale default to 1 instead of 2

2) increase tcp_rmem[2] limit from 4MB to 6MB to take into account
better truesize tracking and to allow autotuning tcp receive window to
reach same value than before. Note that same amount of kernel memory is
consumed compared to 2.6 kernels.

Signed-off-by: Eric Dumazet 
Cc: Neal Cardwell 
Cc: Tom Herbert 
Cc: Yuchung Cheng 
Acked-by: Neal Cardwell 
Signed-off-by: David S. Miller

doc, net: Update ndo_start_xmit return type and values

2012-04-06T06:43:13+00:00

Commit dc1f8bf68b311b1537cb65893430b6796118498a ('netdev: change
transmit to limited range type') changed the required return type and
9a1654ba0b50402a6bd03c7b0fe9b0200a5ea7b1 ('net: Optimize
hard_start_xmit() return checking') changed the valid numerical
return values.

Signed-off-by: Ben Hutchings 
Signed-off-by: David S. Miller

doc, net: Remove instruction to set net_device::trans_start

2012-04-06T06:43:13+00:00

Commit 08baf561083bc27a953aa087dd8a664bb2b88e8e ('net:
txq_trans_update() helper') made it unnecessary for most drivers to
set net_device::trans_start (or netdev_queue::trans_start).

Signed-off-by: Ben Hutchings 
Signed-off-by: David S. Miller

doc, net: Update netdev operation names

2012-04-06T06:43:12+00:00

Commits d314774cf2cd5dfeb39a00d37deee65d4c627927 ('netdev: network
device operations infrastructure') and
008298231abbeb91bc7be9e8b078607b816d1a4a ('netdev: add more functions
to netdevice ops') moved and renamed net device operation pointers.

Signed-off-by: Ben Hutchings 
Signed-off-by: David S. Miller

doc, net: Update documentation of synchronisation for TX multiqueue

2012-04-06T06:43:12+00:00

Commits e308a5d806c852f56590ffdd3834d0df0cbed8d7 ('netdev: Add
netdev->addr_list_lock protection.') and
e8a0464cc950972824e2e128028ae3db666ec1ed ('netdev: Allocate multiple
queues for TX.') introduced more fine-grained locks.

Signed-off-by: Ben Hutchings 
Signed-off-by: David S. Miller

doc, net: Remove obsolete reference to dev->poll

2012-04-06T06:43:12+00:00

Commit bea3348eef27e6044b6161fd04c3152215f96411 ('[NET]: Make NAPI
polling independent of struct net_device objects.') removed the
automatic disabling of NAPI polling by dev_close(), and drivers
must now do this themselves.

Signed-off-by: Ben Hutchings 
Signed-off-by: David S. Miller

TCP: update ip_local_port_range documentation

2012-04-03T21:38:55+00:00

The explanation of ip_local_port_range in
Documentation/networking/ip-sysctl.txt contains several factual
errors:

- The default value of ip_local_port_range does not depend on the
  amount of memory available in the system.
- tcp_tw_recycle is not enabled by default.
- 1024-4999 is not the default value.
- Etc.

Clean up the mess.

Signed-off-by: Fernando Luis Vazquez Cao 
Signed-off-by: David S. Miller