The function ccid2_change_pipe only does an assignment. This patch simplifies the code by
replacing the function with the assignment it performs.
Furthermore, the type of pipe is promoted from `signed' to unsigned (increasing the range).
As a result, a BUG_ON test for negative values now becomes obsolete (for safety not removed,
but replaced with a less annoying `DCCP_BUG').
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The current function ccid2_change_cwnd in effect makes only an assignment, as
the test whether cwnd has reached 0 is only required when cwnd is halved.
This patch simplifies the code by replacing the function with the assignment
it performs.
Furthermore, since ssthresh derives from cwnd and appears in many assignments and
comparisons, the type of ssthresh has also been changed to match that of cwnd.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This replaces the field member `numdupack', which was used as a read-only
constant in the code, with a #define.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This removes a variable `ccid2hctx_sent' which is incremented but
never referenced/read (i.e., dead code).
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This comments out a problematic section comprising a half-finished algorithm:
- The variable `ccid2hctx_ackloss' is never initialised to a value different from 0 and
hence in fact is a read-only constant.
- The `arsent' variable counts packets other than Acks (it is incremented for every packet),
and there is no test for Ack Loss.
- The concept of counting Acks as such leads to a complex calculation, and the calculation
at the moment is inconsistent with this concept.
The problem is that the number of Acks - rather than the number of windows - is counted,
which leads to a complex (cubic/quadratic) expression - this is not even implemented.
In its current state, the commented-out algorithm interfers with normal processing by
changing Ack Ratio incorrectly, and at the wrong times.
A new algorithm is necessary, which will not necessarily use the same variables as used by
the unfinished one; hence the old variables have been removed.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
RFC 4341, sec. 5 states that "The cwnd parameter is initialized to at most
four packets for new connections, following the rules from [RFC3390]", which
is implemented by this patch.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This is because in the next patch CCID2 will assume that dccps_mss_cache is
non-zero.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch removes a bug in the current code. I agree with Andrea's comment
that there is a problem here but the way it is treated does not fix it.
The problem is that whenever Ack Ratio > cwnd, starvation/deadlock occurs:
* the receiver will not send an Ack until (Ack Ratio - cwnd) data packets
have arrived;
* the sender will not send any data packet before the receipt of an Ack
advances the send window.
The only way that the connection then progresses was via RTO timeout. In one
extreme case (bulk transfer), it was observed that this happened for every single
packet; i.e. hundreds of packets, each a RTO timeout of 1..3 seconds apart:
a transfer which normally would take a fraction of a second thus grew to
several minutes.
The solution taken by this approach is to observe the relation
"Ack Ratio <= cwnd"
by using the constraint (1) from RFC 4341, 6.1.2; i.e. set
Ack Ratio = ceil(cwnd / 2)
and update it whenever either Ack Ratio or cwnd change. This ensures that
the deadlock problem can not arise.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Since it makes not sense to assign negative values to Ack Ratio, this
patch disallows this possibility.
As a consequence, a Bug test for negative Ack Ratio values becomes obsolete.
Furthermore, a check against overflow (as Ack Ratio may not exceed 2 bytes,
due to RFC 4340, 11.3) has been added.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
In CCID2 the receiver-history is sorted in ascending order of sequence number,
but the processing of received Ack Vectors requires the list traversal in the
opposite direction.
The current code has a bug in this regard: the list traversal is upwards. As a
consequence, only Ack Vectors with a run length of 1 will pass, in all other
Ack Vectors the remaining (acked) sequence numbers are missed, and may later
falsely be identified as lost.
Note: This bug is only visible when Ack Ratio > 1, since otherwise the run
lengths of Ack Vectors are 0.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This is reduces the length of the struct ackvec/ackvec_record fields. It is
a purely text-based replacement:
s#dccpavr_#avr_#g;
s#dccpav_#av_#g;
and increases readability somewhat.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
I keep getting this build error and couldn't find anyone fixing
it in archives. ...Maybe all net developers except me build
just SMP kernels :-).
In file included from include/net/sock.h:50,
from ipc/mqueue.c:35:
include/linux/pcounter.h: In function 'pcounter_add':
include/linux/pcounter.h:87: error: 'struct pcounter' has no
member named 'value'
make[1]: *** [ipc/mqueue.o] Error 1
make: *** [ipc] Error 2
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
It seems that net/ipv6/af_inet6.c was copied from net/ipv4/af_inet.c,
but one comment was not fixed.
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
The first_unix_socket() and next_unix_sockets() are now used
in proc file and in forall_unix_socets macro only.
The forall_unix_sockets is not used in this file at all so
remove it. After this move the helpers to where they really
belong, i.e. closer to proc code under the #ifdef CONFIG_PROC_FS
option.
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Small update with regard to RFC 4340 (references added as documentation):
on Requests, Ack Vectors / Elapsed Time should be ignored.
Length handling of Elapsed Time also simplified.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This cleans up the consequences of an earlier patch which
introduced the `if IP_DCCP' clause into net/dccp/Kconfig.
The CCID Kconfig menu is sourced within this clause; as a
consequence, all tests of type `depends on IP_DCCP' are now
redundant.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch addresses the following problems:
1. DCCP relies for its proper functioning on having at least one CCID module
enabled (as in TCP plugable congestion control). Currently it is possible to
disable both CCIDs and thus leave the DCCP module in a compiled, but entirely
non-functional state: no sockets can be created when no CCID is available.
Furthermore, the protocol is (again like TCP) not intended to be used without
CCIDs. Last, a non-empty CCID list is needed for doing CCID feature negotiation.
2. Internally the default CCID that is advertised by the Linux host is set to CCID2
(DCCPF_INITIAL_CCID in include/linux/dccp.h). Disabling CCID2 in the Kconfig
menu without changing the defaults leads to a failure `module not found' when
trying to load the dccp module (which internally tries to load the default CCID).
3. The specification (RFC 4340, sec. 10) treats CCID2 somewhat like a
`minimum common denominator'; the specification says that:
* "New connections start with CCID 2 for both endpoints"
* "A DCCP implementation intended for general use, such as an implementation in a
general-purpose operating system kernel, SHOULD implement at least CCID 2.
The intent is to make CCID 2 broadly available for interoperability [...]"
Providing CCID2 as minimum-required CCID (like Reno/Cubic in TCP) thus seems reasonable.
Hence this patch automatically selects CCID2 when DCCP is enabled. Documentation also added.
Discussions with Ian McDonald on this subject are gratefully acknowledged.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This updates the DCCP documentation, following input from Ian McDonald,
clarifiying the status of DCCP, and adding a note about the test tree.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This extends the DCCP socket API by honouring any shutdown(2) option set by the user.
The behaviour is, as much as possible, made consistent with the API for TCP's shutdown.
This patch exploits the information provided by the user via the socket API to reduce
processing costs:
* if the read end is closed (SHUT_RD), it is not necessary to deliver to input CCID;
* if the write end is closed (SHUT_WR), the same idea applies, but with a difference -
as long as the TX queue has not been drained, we need to receive feedback to keep
congestion-control rates up to date. Hence SHUT_WR is honoured only after the last
packet (under congestion control) has been sent;
* although SHUT_RDWR seems nonsensical, it is nevertheless supported in the same manner
as for TCP (and agrees with test for SHUTDOWN_MASK in dccp_poll() in net/dccp/proto.c).
Furthermore, most of the code already honours the sk_shutdown flags (dccp_recvmsg() for
instance sets the read length to 0 if SHUT_RD had been called); CCID handling is now added
to this by the present patch.
There will also no longer be any delivery when the socket is in the final stages, i.e. when
one of dccp_close(), dccp_fin(), or dccp_done() has been called - which is fine since at
that stage the connection is its final stages.
Motivation and background are on http://www.erg.abdn.ac.uk/users/gerrit/dccp/notes/shutdown
A FIXME has been added to notify the other end if SHUT_RD has been set (RFC 4340, 11.7).
Note: There is a comment in inet_shutdown() in net/ipv4/af_inet.c which asks to "make
sure the socket is a TCP socket". This should probably be extended to mean
`TCP or DCCP socket' (the code is also used by UDP and raw sockets).
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This decouples PARTOPEN from TCP-specific stream-states.
It thus addresses the FIXME.
The code has been checked with regard to dependency on PARTOPEN and FIN_WAIT1
states (to which PARTOPEN previously was mapped): there is no difference, as
PARTOPEN is always referred to directly (i.e. not via the mapping to TCP
state).
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This fixes/updates the handling of idle and application-limited periods in CCID3,
which currently is broken: there is no detection as to how long a sender has been
idle - there is only one flag which is toggled in between function calls.
Being obsolete now, the `idle' flag is removed.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch fixes a previously undiscovered bug; the problem is in computing
the elapsed time as the time between `receiving' the packet (i.e. skb enters
CCID module) and sending feedback:
- there is no layer-processing, queueing, or delay involved,
- hence the elapsed time is in the order of 1 function call
- this is in the dimension of maximally 50..100usec
- which renders the use of elapsed time almost entirely useless.
The fix is simply to ignore such trivial amounts of elapsed time.
As a further advantage, the now useless elapsed_time field can be removed from
the socket, which reduces the socket structure by another four bytes.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Gerrit Renker
Arnaldo Carvalho de Melo
Ilpo Järvinen
Pavel Emelyanov