The identification of this bug is thanks to Cheng Wei and Tomasz
Grobelny.
To avoid divide-by-zero, the implementation previously ignored RTTs
smaller than 4 microseconds when performing integer division RTT/4.
When the RTT reached a value less than 4 microseconds (as observed on
loopback), this prevented the Window Counter CCVal value from
advancing. As a result, the receiver stopped sending feedback. This in
turn caused non-ending expiries of the nofeedback timer at the sender,
so that the sending rate was progressively reduced until reaching the
minimum of one packet per 64 seconds.
The patch fixes this bug by handling integer division more
intelligently. Due to consistent use of dccp_sample_rtt(),
divide-by-zero-RTT is avoided.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
This implements the changes to the nofeedback timer handling suggested
in draft rfc3448bis00, section 4.4. In particular, these changes mean:
* better handling of the lossless case (p == 0)
* the timestamp for computing t_ld becomes obsolete
* much more recent document (RFC 3448 is almost 5 years old)
* concepts in rfc3448bis arose from a real, working implementation
(cf. sec. 12)
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 implements the algorithm to update the allowed sending rate X upon
receiving feedback packets, as described in draft rfc3448bis, 4.2/4.3.
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 NO_SENT state is only triggered in bidirectional mode,
costing unnecessary processing.
* the TERM (terminating) state is irrelevant.
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
1) concentrates previously scattered computation of p_inv into one function;
2) removes the `p' element of the CCID3 RX sock (it is redundant);
3) makes the tfrc_rx_info structure standalone, only used on demand.
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 patch makes the registration messages of CCID 2/3 a bit more
informative: instead of repeating the CCID number as currently done,
"CCID: Registered CCID 2 (ccid2)" or
"CCID: Registered CCID 3 (ccid3)",
the descriptive names of the CCID's (from RFCs) are now used:
"CCID: Registered CCID 2 (TCP-like)" and
"CCID: Registered CCID 3 (TCP-Friendly Rate Control)".
To allow spaces in the name, the slab name string has been changed to
refer to the numeric CCID identifier, using the same format as before.
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 hooks up the TFRC Loss Interval database with CCID 3 packet reception.
In addition, it makes the CCID-specific computation of the first loss
interval (which requires access to all the guts of CCID3) local to ccid3.c.
The patch also fixes an omission in the DCCP code, that of a default /
fallback RTT value (defined in section 3.4 of RFC 4340 as 0.2 sec); while
at it, the upper bound of 4 seconds for an RTT sample has been reduced to
match the initial TCP RTO value of 3 seconds from[RFC 1122, 4.2.3.1].
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>
Each time feedback is sent two lines are printed:
ccid3_hc_rx_send_feedback: client ... - entry
ccid3_hc_rx_send_feedback: Interval ...usec, X_recv=..., 1/p=...
The first line is redundant and thus removed.
Further, documentation of ccid3_hc_rx_sock (capitalisation) is made consistent.
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>
Credit here goes to Gerrit Renker, that provided the initial implementation for
this new codebase.
I modified it just to try to make it closer to the existing API, renaming some
functions, add namespacing and fix one bug where the tfrc_rx_hist_alloc was not
freeing the allocated ring entries on the error path.
Original changeset comment from Gerrit:
-----------
This provides a new, self-contained and generic RX history service for TFRC
based protocols.
Details:
* new data structure, initialisation and cleanup routines;
* allocation of dccp_rx_hist entries local to packet_history.c,
as a service exported by the dccp_tfrc_lib module.
* interface to automatically track highest-received seqno;
* receiver-based RTT estimation (needed for instance by RFC 3448, 6.3.1);
* a generic function to test for `data packets' as per RFC 4340, sec. 7.7.
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>
This is in preparation for merging the new rx history code written by Gerrit Renker.
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>
This is in preparation for merging the new rx history code written by Gerrit Renker.
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>
Based on a previous patch by Gerrit Renker.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch was based on another made by Gerrit Renker, his changelog was:
------------------------------------------------------
The patch set migrates TFRC TX history to a singly-linked list.
The details are:
* use of a consistent naming scheme (all TFRC functions now begin with `tfrc_');
* allocation and cleanup are taken care of internally;
* provision of a lookup function, which is used by the CCID TX infrastructure
to determine the time a packet was sent (in turn used for RTT sampling);
* integration of the new interface with the present use in CCID3.
------------------------------------------------------
Simplifications I did:
. removing the tfrc_tx_hist_head that had a pointer to the list head and
another for the slabcache.
. No need for creating a slabcache for each CCID that wants to use the TFRC
tx history routines, create a single slabcache when the dccp_tfrc_lib module
init routine is called.
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>
This updates the CCID3 code with regard to two instances of using `MSS' in place of `s':
1. The RFC3390-based initial rate: both rfc3448bis as well as the Faster Restart
draft now consistently use `s' instead of MSS.
2. Now agrees with section 4.2 of rfc3448bis: "If the sender is ready to send data when
it does not yet have a round trip sample, the value of X is set to s bytes per
second, for segment size s [...]"
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>
Many-many code in the kernel initialized the timer->function
and timer->data together with calling init_timer(timer). There
is already a helper for this. Use it for networking code.
The patch is HUGE, but makes the code 130 lines shorter
(98 insertions(+), 228 deletions(-)).
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Assigning initial values of `0' is redundant when loading a new CCID structure,
since in net/dccp/ccid.c the entire CCID structure is zeroed out prior to
initialisation in ccid_new():
struct ccid {
struct ccid_operations *ccid_ops;
char ccid_priv[0];
};
// ...
if (rx) {
memset(ccid + 1, 0, ccid_ops->ccid_hc_rx_obj_size);
if (ccid->ccid_ops->ccid_hc_rx_init != NULL &&
ccid->ccid_ops->ccid_hc_rx_init(ccid, sk) != 0)
goto out_free_ccid;
} else {
memset(ccid + 1, 0, ccid_ops->ccid_hc_tx_obj_size);
/* analogous to the rx case */
}
This patch therefore removes the redundant assignments. Thanks to Arnaldo for
the inspiration.
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>
This fixes `unaligned (read) access' errors of the type
Kernel unaligned access at TPC[100f970c] dccp_parse_options+0x4f4/0x7e0 [dccp]
Kernel unaligned access at TPC[1011f2e4] ccid3_hc_tx_parse_options+0x1ac/0x380 [dccp_ccid3]
Kernel unaligned access at TPC[100f9898] dccp_parse_options+0x680/0x880 [dccp]
by using the get_unaligned macro for parsing options.
Commiter note: Preserved the sparse __be{16,32} annotations.
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>
