With this patch, TX/RX CCIDs can now be changed on a per-connection
basis, which overrides the defaults set by the global sysctl variables
for TX/RX CCIDs.

To make full use of this facility, the remaining patches of this patch
set are needed, which track dependencies and activate negotiated
feature values.
Signed-off-by: NGerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch prepares RCU migration of listening_hash table for
TCP/DCCP protocols.

listening_hash table being small (32 slots per protocol), we add
a spinlock for each slot, instead of a single rwlock for whole table.

This should reduce hold time of readers, and writers concurrency.
Signed-off-by: NEric Dumazet <dada1@cosmosbay.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This splits the setsockopt calls into two groups, depending on whether an
integer argument (val) is required and whether routines being called do
their own locking.

Some options (such as setting the CCID) use u8 rather than int, so that for
these the test with regard to integer-sizeof can not be used.

The second switch-case statement now only has those statements which need
locking and which make use of `val'.
Signed-off-by: NGerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: NIan McDonald <ian.mcdonald@jandi.co.nz>
Acked-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Reviewed-by: NEugene Teo <eugeneteo@kernel.sg>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This provides feature negotiation for server minimum checksum coverage
which so far has been missing.

Since sender/receiver coverage values range only from 0...15, their
type has also been reduced in size from u16 to u4.

Feature-negotiation options are now generated for both sender and receiver
coverage, i.e. when the peer has `forgotten' to enable partial coverage
then feature negotiation will automatically enable (negotiate) the partial
coverage value for this connection.
Signed-off-by: NGerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: NIan McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The previous setsockopt interface, which passed socket options via struct
dccp_so_feat, is complicated/difficult to use. Continuing to support it leads to
ugly code since the old approach did not distinguish between NN and SP values.

This patch removes the old setsockopt interface and replaces it with two new
functions to register NN/SP values for feature negotiation. 
These are essentially wrappers around the internal __feat_register functions,
with checking added to avoid

 * wrong usage (type);
 * changing values while the connection is in progress.
Signed-off-by: NGerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

RCU was added to UDP lookups, using a fast infrastructure :
- sockets kmem_cache use SLAB_DESTROY_BY_RCU and dont pay the
  price of call_rcu() at freeing time.
- hlist_nulls permits to use few memory barriers.

This patch uses same infrastructure for TCP/DCCP established
and timewait sockets.

Thanks to SLAB_DESTROY_BY_RCU, no slowdown for applications
using short lived TCP connections. A followup patch, converting
rwlocks to spinlocks will even speedup this case.

__inet_lookup_established() is pretty fast now we dont have to
dirty a contended cache line (read_lock/read_unlock)

Only established and timewait hashtable are converted to RCU
(bind table and listen table are still using traditional locking)
Signed-off-by: NEric Dumazet <dada1@cosmosbay.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This provides a missing link in the code chain, as several features implicitly
depend and/or rely on the choice of CCID. Most notably, this is the Send Ack Vector
feature, but also Ack Ratio and Send Loss Event Rate (also taken care of).

For Send Ack Vector, the situation is as follows:
 * since CCID2 mandates the use of Ack Vectors, there is no point in allowing 
   endpoints which use CCID2 to disable Ack Vector features such a connection;

 * a peer with a TX CCID of CCID2 will always expect Ack Vectors, and a peer
   with a RX CCID of CCID2 must always send Ack Vectors (RFC 4341, sec. 4);

 * for all other CCIDs, the use of (Send) Ack Vector is optional and thus
   negotiable. However, this implies that the code negotiating the use of Ack
   Vectors also supports it (i.e. is able to supply and to either parse or
   ignore received Ack Vectors). Since this is not the case (CCID-3 has no Ack
   Vector support), the use of Ack Vectors is here disabled, with a comment
   in the source code.

An analogous consideration arises for the Send Loss Event Rate feature,
since the CCID-3 implementation does not support the loss interval options
of RFC 4342. To make such use explicit, corresponding feature-negotiation
options are inserted which signal the use of the loss event rate option,
as it is used by the CCID3 code.

Lastly, the values of the Ack Ratio feature are matched to the choice of CCID.

The patch implements this as a function which is called after the user has
made all other registrations for changing default values of features.

The table is variable-length, the reserved (and hence for feature-negotiation
invalid, confirmed by considering section 19.4 of RFC 4340) feature number `0'
is used to mark the end of the table.
Signed-off-by: NGerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: NIan McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This provides a data structure to record which CCIDs are locally supported
and three accessor functions:
 - a test function for internal use which is used to validate CCID requests
   made by the user;
 - a copy function so that the list can be used for feature-negotiation;   
 - documented getsockopt() support so that the user can query capabilities.

The data structure is a table which is filled in at compile-time with the
list of available CCIDs (which in turn depends on the Kconfig choices).

Using the copy function for cloning the list of supported CCIDs is useful for
feature negotiation, since the negotiation is now with the full list of available
CCIDs (e.g. {2, 3}) instead of the default value {2}. This means negotiation 
will not fail if the peer requests to use CCID3 instead of CCID2. 
Signed-off-by: NGerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: NIan McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Two registration routines, for SP and NN features, are provided by this patch,
replacing a previous routine which was used for both feature types.

These are internal-only routines and therefore start with `__feat_register'.

It further exports the known limits of Sequence Window and Ack Ratio as symbolic
constants.
Signed-off-by: NGerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: NIan McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This inserts the required de-allocation routines for memory allocated
by feature negotiation in the socket destructors, replacing
dccp_feat_clean() in one instance.
Signed-off-by: NGerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: NIan McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This provides feature-negotiation initialisation for both DCCP sockets
and DCCP request_sockets, to support feature negotiation during
connection setup.

It also resolves a FIXME regarding the congestion control
initialisation.

Thanks to Wei Yongjun for help with the IPv6 side of this patch.
Signed-off-by: NGerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: NIan McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

as it accentally contained the wrong set of patches. These will be
submitted separately.
Signed-off-by: NGerrit Renker <gerrit@erg.abdn.ac.uk>

This migrates more TFRC-related code into the dccp_tfrc_lib:
 * sampling of the packet size `s' (which is only needed until the first
   loss interval is computed (ccid3_first_li));
 * updating the byte-counter `bytes_recvd' in between sending feedbacks.
The result is a better separation of CCID-3 specific and TFRC specific
code, which aids future integration with ECN and e.g. CCID-4.

Further changes:
----------------
 * replaced magic number of 536 with equivalent constant TCP_MIN_RCVMSS;
   (this constant is also used when no estimate for `s' is available).
Signed-off-by: NGerrit Renker <gerrit@erg.abdn.ac.uk>

Ensure that cmsg->cmsg_type value is valid for qpolicy 
that is currently in use.
Signed-off-by: NTomasz Grobelny <tomasz@grobelny.oswiecenia.net>
Signed-off-by: NGerrit Renker <gerrit@erg.abdn.ac.uk>

This patch adds a generic infrastructure for policy-based dequeueing of 
TX packets and provides two policies:
 * a simple FIFO policy (which is the default) and
 * a priority based policy (set via socket options).
Both policies honour the tx_qlen sysctl for the maximum size of the write
queue (can be overridden via socket options). 

The priority policy uses skb->priority internally to assign an u32 priority
identifier, using the same ranking as SO_PRIORITY. The skb->priority field
is set to 0 when the packet leaves DCCP. The priority is supplied as ancillary
data using cmsg(3), the patch also provides the requisite parsing routines.
Signed-off-by: NTomasz Grobelny <tomasz@grobelny.oswiecenia.net>
Signed-off-by: NGerrit Renker <gerrit@erg.abdn.ac.uk>

This extends the existing wait-for-ccid routine so that it may be used with
different types of CCID. It further addresses the problems listed below.

The code looks if the write queue is non-empty and grants the TX CCID up to
`timeout' jiffies to drain the queue. It will instead purge that queue if
 * the delay suggested by the CCID exceeds the time budget;
 * a socket error occurred while waiting for the CCID;
 * there is a signal pending (eg. annoyed user pressed Control-C);
 * the CCID does not support delays (we don't know how long it will take).


                 D e t a i l s  [can be removed]
                 -------------------------------
DCCP's sending mechanism functions a bit like non-blocking I/O: dccp_sendmsg()
will enqueue up to net.dccp.default.tx_qlen packets (default=5), without waiting
for them to be released to the network.

Rate-based CCIDs, such as CCID3/4, can impose sending delays of up to maximally
64 seconds (t_mbi in RFC 3448). Hence the write queue may still contain packets
when the application closes. Since the write queue is congestion-controlled by
the CCID, draining the queue is also under control of the CCID.

There are several problems that needed to be addressed:
 1) The queue-drain mechanism only works with rate-based CCIDs. If CCID2 for
    example has a full TX queue and becomes network-limited just as the
    application wants to close, then waiting for CCID2 to become unblocked could
    lead to an indefinite  delay (i.e., application "hangs").
 2) Since each TX CCID in turn uses a feedback mechanism, there may be changes
    in its sending policy while the queue is being drained. This can lead to
    further delays during which the application will not be able to terminate.
 3) The minimum wait time for CCID3/4 can be expected to be the queue length
    times the current inter-packet delay. For example if tx_qlen=100 and a delay
    of 15 ms is used for each packet, then the application would have to wait
    for a minimum of 1.5 seconds before being allowed to exit.
 4) There is no way for the user/application to control this behaviour. It would
    be good to use the timeout argument of dccp_close() as an upper bound. Then
    the maximum time that an application is willing to wait for its CCIDs to can
    be set via the SO_LINGER option.

These problems are addressed by giving the CCID a grace period of up to the
`timeout' value.

The wait-for-ccid function is, as before, used when the application 
 (a) has read all the data in its receive buffer and
 (b) if SO_LINGER was set with a non-zero linger time, or
 (c) the socket is either in the OPEN (active close) or in the PASSIVE_CLOSEREQ
     state (client application closes after receiving CloseReq).

In addition, there is a catch-all case by calling __skb_queue_purge() after 
waiting for the CCID. This is necessary since the write queue may still have
data when
 (a) the host has been passively-closed,
 (b) abnormal termination (unread data, zero linger time),
 (c) wait-for-ccid could not finish within the given time limit.
Signed-off-by: NGerrit Renker <gerrit@erg.abdn.ac.uk>

This uses the new feature-negotiation framework to signal Ack Ratio changes,
as required by RFC 4341, sec. 6.1.2.

This raises some problems for CCID-2 since it can at the moment not cope
gracefully with Ack Ratio of e.g. 2. A FIXME has thus been added which
reverts to the existing policy of bypassing the Ack Ratio sysctl.
Signed-off-by: NGerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: NIan McDonald <ian.mcdonald@jandi.co.nz>

This adds full support for local/remote Sequence Window feature, from which the 
  * sequence-number-validity (W) and 
  * acknowledgment-number-validity (W') windows 
derive as specified in RFC 4340, 7.5.3. 

Specifically, the following changes are introduced:
  * integrated new socket fields into dccp_sk;
  * updated the update_gsr/gss routines with regard to these fields;
  * updated handler code: the Sequence Window feature is located at the TX side,
    so the local feature is meant if the handler-rx flag is false;
  * the initialisation of `rcv_wnd' in reqsk is removed, since
    - rcv_wnd is not used by the code anywhere;
    - sequence number checks are not done in the LISTEN state (cf. 7.5.3);
    - dccp_check_req checks the Ack number validity more rigorously;
  * the `struct dccp_minisock' became empty and is now removed.

Until the handshake completes with activating negotiated values, the local/remote
Sequence-Window values are undefined and thus can not reliably be estimated.
This issue is addressed in a separate patch.
Signed-off-by: NGerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: NIan McDonald <ian.mcdonald@jandi.co.nz>

This removes the use of the sysctl and the minisock variable for the Send Ack
Vector feature, which is now handled fully dynamically via feature negotiation;
i.e. when CCID2 is enabled, Ack Vectors are automatically enabled (as per
RFC 4341, 4.).

Using a sysctl in parallel to this implementation would open the door to
crashes, since much of the code relies on tests of the boolean minisock /
sysctl variable. Thus, this patch replaces all tests of type

	if (dccp_msk(sk)->dccpms_send_ack_vector)
		/* ... */
with
	if (dp->dccps_hc_rx_ackvec != NULL)
		/* ... */

The dccps_hc_rx_ackvec is allocated by the dccp_hdlr_ackvec() when feature
negotiation concluded that Ack Vectors are to be used on the half-connection.
Otherwise, it is NULL (due to dccp_init_sock/dccp_create_openreq_child),
so that the test is a valid one.

The activation handler for Ack Vectors is called as soon as the feature
negotiation has concluded at the
 * server when the Ack marking the transition RESPOND => OPEN arrives;
 * client after it has sent its ACK, marking the transition REQUEST => PARTOPEN.

Adding the sequence number of the Response packet to the Ack Vector has been 
removed, since
 (a) connection establishment implies that the Response has been received;
 (b) the CCIDs only look at packets received in the (PART)OPEN state, i.e.
     this entry will always be ignored;
 (c) it can not be used for anything useful - to detect loss for instance, only
     packets received after the loss can serve as pseudo-dupacks.
Signed-off-by: NGerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: NIan McDonald <ian.mcdonald@jandi.co.nz>

This first patch out of three replaces the hardcoded default settings with
initialisation code for the dynamic feature negotiation.

Note on retransmitting Confirm options:
---------------------------------------
This patch also defers flushing the client feature-negotiation queue,
due to the following considerations.

As long as the client is in PARTOPEN, it needs to retransmit the Confirm
options for the Change options received on the DCCP-Response from the server.

Otherwise, if the packet containing the Confirm options gets dropped in the 
network, the connection aborts due to undefined feature negotiation state.

Thanks to Leandro Melo de Sales who reported a bug in an earlier revision
of the patch set, resulting from not retransmitting the Confirm options.

The patch now ensures that the client feature-negotiation queue is flushed only
when entering the OPEN state. Since confirmed Change options are removed as
soon as they are confirmed (in the DCCP-Response), this ensures that Confirm
options are retransmitted.
Signed-off-by: NGerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: NIan McDonald <ian.mcdonald@jandi.co.nz>

This provides function to query the current TX/RX CCID dynamically, without
reliance on the minisock value, using dynamic information available in the
currently loaded CCID module.

This query function is then used to 
 (a) provide the getsockopt part for getting/setting CCIDs via sockopts;
 (b) replace the current test for "which CCID is in use" in probe.c.
Signed-off-by: NGerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: NIan McDonald <ian.mcdonald@jandi.co.nz>

With this patch, TX/RX CCIDs can now be changed on a per-connection basis, which
overrides the defaults set by the global sysctl variables for TX/RX CCIDs.

To make full use of this facility, the remaining patches of this patch set are
needed, which track dependencies and activate negotiated feature values.

Note on the maximum number of CCIDs that can be registered:
-----------------------------------------------------------
The maximum number of CCIDs that can be registered on the socket is constrained
by the space in a Confirm/Change feature negotiation option. 

The space in these in turn depends on the size of header options as defined
in RFC 4340, 5.8. Since this is a recurring constant, it has been moved from
ackvec.h into linux/dccp.h, clarifying its purpose.

Relative to this size, the maximum number of CCID identifiers that can be 
present in a Confirm option (which always consumes 1 byte more than a Change
option, cf. 6.1) is 2 bytes less than the maximum TLV size: one for the
CCID-feature-type and one for the selected value.
Signed-off-by: NGerrit Renker <gerrit@erg.abdn.ac.uk>

This splits the setsockopt calls into two groups, depending on whether an
integer argument (val) is required and whether routines being called do
their own locking.

Some options (such as setting the CCID) use u8 rather than int, so that for
these the test with regard to integer-sizeof can not be used.

The second switch-case statement now only has those statements which need
locking and which make use of `val'.
Signed-off-by: NGerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: NIan McDonald <ian.mcdonald@jandi.co.nz>
Acked-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Reviewed-by: NEugene Teo <eugeneteo@kernel.sg>

This provides feature negotiation for server minimum checksum coverage
which so far has been missing.

Since sender/receiver coverage values range only from 0...15, their
type has also been reduced in size from u16 to u4.

Feature-negotiation options are now generated for both sender and receiver
coverage, i.e. when the peer has `forgotten' to enable partial coverage
then feature negotiation will automatically enable (negotiate) the partial
coverage value for this connection.
Signed-off-by: NGerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: NIan McDonald <ian.mcdonald@jandi.co.nz>

The previous setsockopt interface, which passed socket options via struct 
dccp_so_feat, is complicated/difficult to use. Continuing to support it leads to
ugly code since the old approach did not distinguish between NN and SP values.

This patch removes the old setsockopt interface and replaces it with two new
functions to register NN/SP values for feature negotiation. These are 
essentially wrappers around the internal __feat_register functions, with 
checking added to avoid
 * wrong usage (type);
 * changing values while the connection is in progress.
Signed-off-by: NGerrit Renker <gerrit@erg.abdn.ac.uk>

This provides a missing link in the code chain, as several features implicitly
depend and/or rely on the choice of CCID. Most notably, this is the Send Ack Vector
feature, but also Ack Ratio and Send Loss Event Rate (also taken care of).

For Send Ack Vector, the situation is as follows:
 * since CCID2 mandates the use of Ack Vectors, there is no point in allowing 
   endpoints which use CCID2 to disable Ack Vector features such a connection;

 * a peer with a TX CCID of CCID2 will always expect Ack Vectors, and a peer
   with a RX CCID of CCID2 must always send Ack Vectors (RFC 4341, sec. 4);

 * for all other CCIDs, the use of (Send) Ack Vector is optional and thus
   negotiable. However, this implies that the code negotiating the use of Ack
   Vectors also supports it (i.e. is able to supply and to either parse or
   ignore received Ack Vectors). Since this is not the case (CCID-3 has no Ack
   Vector support), the use of Ack Vectors is here disabled, with a comment
   in the source code.

An analogous consideration arises for the Send Loss Event Rate feature,
since the CCID-3 implementation does not support the loss interval options
of RFC 4342. To make such use explicit, corresponding feature-negotiation
options are inserted which signal the use of the loss event rate option,
as it is used by the CCID3 code.

Lastly, the values of the Ack Ratio feature are matched to the choice of CCID.

The patch implements this as a function which is called after the user has
made all other registrations for changing default values of features.

The table is variable-length, the reserved (and hence for feature-negotiation
invalid, confirmed by considering section 19.4 of RFC 4340) feature number `0'
is used to mark the end of the table.
Signed-off-by: NGerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: NIan McDonald <ian.mcdonald@jandi.co.nz>

This provides a data structure to record which CCIDs are locally supported
and three accessor functions:
 - a test function for internal use which is used to validate CCID requests
   made by the user;
 - a copy function so that the list can be used for feature-negotiation;   
 - documented getsockopt() support so that the user can query capabilities.

The data structure is a table which is filled in at compile-time with the
list of available CCIDs (which in turn depends on the Kconfig choices).

Using the copy function for cloning the list of supported CCIDs is useful for
feature negotiation, since the negotiation is now with the full list of available
CCIDs (e.g. {2, 3}) instead of the default value {2}. This means negotiation 
will not fail if the peer requests to use CCID3 instead of CCID2. 
Signed-off-by: NGerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: NIan McDonald <ian.mcdonald@jandi.co.nz>

Two registration routines, for SP and NN features, are provided by this patch,
replacing a previous routine which was used for both feature types.

These are internal-only routines and therefore start with `__feat_register'.

It further exports the known limits of Sequence Window and Ack Ratio as symbolic
constants.
Signed-off-by: NGerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: NIan McDonald <ian.mcdonald@jandi.co.nz>

This inserts the required de-allocation routines for memory allocated by 
feature negotiation in the socket destructors, replacing dccp_feat_clean()
in one instance.
Signed-off-by: NGerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: NIan McDonald <ian.mcdonald@jandi.co.nz>

This provides feature-negotiation initialisation for both DCCP sockets and
DCCP request_sockets, to support feature negotiation during connection setup.

It also resolves a FIXME regarding the congestion control initialisation.

Thanks to Wei Yongjun for help with the IPv6 side of this patch.
Signed-off-by: NGerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: NIan McDonald <ian.mcdonald@jandi.co.nz>

This sets the sysfs permissions so that root can toggle the `debug'
parameter available for nearly every DCCP module. This is useful 
since there are various module inter-dependencies. The debug flag
can now be toggled at runtime using

  echo 1 > /sys/module/dccp/parameters/dccp_debug
  echo 1 > /sys/module/dccp_ccid2/parameters/ccid2_debug
  echo 1 > /sys/module/dccp_ccid3/parameters/ccid3_debug
  echo 1 > /sys/module/dccp_tfrc_lib/parameters/tfrc_debug

The last is not very useful yet, since no code at the moment calls
the tfrc_debug() macro.
Signed-off-by: NGerrit Renker <gerrit@erg.abdn.ac.uk>

dccp_disconnect() can be called due to several reasons:

 1. when the connection setup failed (inet_stream_connect());
 2. when shutting down (inet_shutdown(), inet_csk_listen_stop());
 3. when aborting the connection (dccp_close() with 0 linger time).

In case (1) the write queue is empty. This patch empties the write queue,
if in case (2) or (3) it was not yet empty.

This avoids triggering the write-queue BUG_TRAP in sk_stream_kill_queues()
later on.

It also seems natural to do: when breaking an association, to delete all
packets that were originally intended for the soon-disconnected end (compare
with call to tcp_write_queue_purge in tcp_disconnect()).
Signed-off-by: NGerrit Renker <gerrit@erg.abdn.ac.uk>

This sets the sysfs permissions so that root can toggle the `debug'
parameter available for nearly every DCCP module. This is useful 
since there are various module inter-dependencies. The debug flag
can now be toggled at runtime using

  echo 1 > /sys/module/dccp/parameters/dccp_debug
  echo 1 > /sys/module/dccp_ccid2/parameters/ccid2_debug
  echo 1 > /sys/module/dccp_ccid3/parameters/ccid3_debug
  echo 1 > /sys/module/dccp_tfrc_lib/parameters/tfrc_debug

The last is not very useful yet, since no code at the moment calls
the tfrc_debug() macro.
Signed-off-by: NGerrit Renker <gerrit@erg.abdn.ac.uk>

dccp_disconnect() can be called due to several reasons:

 1. when the connection setup failed (inet_stream_connect());
 2. when shutting down (inet_shutdown(), inet_csk_listen_stop());
 3. when aborting the connection (dccp_close() with 0 linger time).

In case (1) the write queue is empty. This patch empties the write queue,
if in case (2) or (3) it was not yet empty.

This avoids triggering the write-queue BUG_TRAP in sk_stream_kill_queues()
later on.

It also seems natural to do: when breaking an association, to delete all
packets that were originally intended for the soon-disconnected end (compare
with call to tcp_write_queue_purge in tcp_disconnect()).
Signed-off-by: NGerrit Renker <gerrit@erg.abdn.ac.uk>

    
Thanks to Eugene Teo for reporting this problem.
Signed-off-by: NEugene Teo <eugenete@kernel.sg>
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: NGerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Removes legacy reinvent-the-wheel type thing. The generic
machinery integrates much better to automated debugging aids
such as kerneloops.org (and others), and is unambiguous due to
better naming. Non-intuively BUG_TRAP() is actually equal to
WARN_ON() rather than BUG_ON() though some might actually be
promoted to BUG_ON() but I left that to future.

I could make at least one BUILD_BUG_ON conversion.
Signed-off-by: NIlpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Change struct proto destroy function pointer to return void.  Noticed
by Al Viro.
Signed-off-by: NBrian Haley <brian.haley@hp.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

None of these files use any of the functionality promised by
asm/semaphore.h.  It's possible that they rely on it dragging in some
unrelated header file, but I can't build all these files, so we'll have
fix any build failures as they come up.
Signed-off-by: NMatthew Wilcox <willy@linux.intel.com>

dev_queue_xmit() and the other IP output functions expect to get a skb
with clear or properly initialized skb->cb. Unlike TCP and UDP, the
dccp_skb_cb doesn't contain a struct inet_skb_parm at the beginning,
so the DCCP-specific data is interpreted by the IP output functions.
This can cause false negatives for the conditional POST_ROUTING hook
invocation, making the packet bypass the hook.

Add a inet_skb_parm/inet6_skb_parm union to the beginning of
dccp_skb_cb to avoid clashes. Also add a BUILD_BUG_ON to make
sure it fits in the cb.

[ Combined with patch from Gerrit Renker to remove two now unnecessary
  memsets of IPCB(skb)->opt ]
Signed-off-by: NPatrick McHardy <kaber@trash.net>
Acked-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NYOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Acked-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>