Commit Graph

507 Commits

Author SHA1 Message Date
David Howells c31410ea00 rxrpc: Remove error from struct rxrpc_skb_priv as it is unused
Remove error from struct rxrpc_skb_priv as it is no longer used.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-30 14:39:32 +01:00
David Howells 775e5b71db rxrpc: The offset field in struct rxrpc_skb_priv is unnecessary
The offset field in struct rxrpc_skb_priv is unnecessary as the value can
always be calculated.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-30 14:39:28 +01:00
David Howells 0851115090 rxrpc: Reduce ssthresh to peer's receive window
When we receive an ACK from the peer that tells us what the peer's receive
window (rwind) is, we should reduce ssthresh to rwind if rwind is smaller
than ssthresh.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-30 14:38:59 +01:00
David Howells 8782def204 rxrpc: Switch to Congestion Avoidance mode at cwnd==ssthresh
Switch to Congestion Avoidance mode at cwnd == ssthresh rather than relying
on cwnd getting incremented beyond ssthresh and the window size, the mode
being shifted and then cwnd being corrected.

We need to make sure we switch into CA mode so that we stop marking every
packet for ACK.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-30 14:38:56 +01:00
David Howells ed1e8679d8 rxrpc: Note serial number being ACK'd in the congestion management trace
Note the serial number of the packet being ACK'd in the congestion
management trace rather than the serial number of the ACK packet.  Whilst
the serial number of the ACK packet is useful for matching ACK packet in
the output of wireshark, the serial number that the ACK is in response to
is of more use in working out how different trace lines relate.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-29 22:57:47 +01:00
David Howells b112a67081 rxrpc: Request more ACKs in slow-start mode
Set the request-ACK on more DATA packets whilst we're in slow start mode so
that we get sufficient ACKs back to supply information to configure the
window.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-29 22:57:47 +01:00
David Howells 1e9e5c9521 rxrpc: Reduce the rxrpc_local::services list to a pointer
Reduce the rxrpc_local::services list to just a pointer as we don't permit
multiple service endpoints to bind to a single transport endpoints (this is
excluded by rxrpc_lookup_local()).

The reason we don't allow this is that if you send a request to an AFS
filesystem service, it will try to talk back to your cache manager on the
port you sent from (this is how file change notifications are handled).  To
prevent someone from stealing your CM callbacks, we don't let AF_RXRPC
sockets share a UDP socket if at least one of them has a service bound.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-29 22:57:47 +01:00
David Howells 2629c7fa7c rxrpc: When activating client conn channels, do state check inside lock
In rxrpc_activate_channels(), the connection cache state is checked outside
of the lock, which means it can change whilst we're waking calls up,
thereby changing whether or not we're allowed to wake calls up.

Fix this by moving the check inside the locked region.  The check to see if
all the channels are currently busy can stay outside of the locked region.

Whilst we're at it:

 (1) Split the locked section out into its own function so that we can call
     it from other places in a later patch.

 (2) Determine the mask of channels dependent on the state as we're going
     to add another state in a later patch that will restrict the number of
     simultaneous calls to 1 on a connection.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-29 22:57:47 +01:00
David Howells a1767077b0 rxrpc: Make Tx loss-injection go through normal return and adjust tracing
In rxrpc_send_data_packet() make the loss-injection path return through the
same code as the transmission path so that the RTT determination is
initiated and any future timer shuffling will be done, despite the packet
having been binned.

Whilst we're at it:

 (1) Add to the tx_data tracepoint an indication of whether or not we're
     retransmitting a data packet.

 (2) When we're deciding whether or not to request an ACK, rather than
     checking if we're in fast-retransmit mode check instead if we're
     retransmitting.

 (3) Don't invoke the lose_skb tracepoint when losing a Tx packet as we're
     not altering the sk_buff refcount nor are we just seeing it after
     getting it off the Tx list.

 (4) The rxrpc_skb_tx_lost note is then no longer used so remove it.

 (5) rxrpc_lose_skb() no longer needs to deal with rxrpc_skb_tx_lost.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-29 22:37:15 +01:00
David Howells 8732db67c6 rxrpc: Fix exclusive client connections
Exclusive connections are currently reusable (which they shouldn't be)
because rxrpc_alloc_client_connection() checks the exclusive flag in the
rxrpc_connection struct before it's initialised from the function
parameters.  This means that the DONT_REUSE flag doesn't get set.

Fix this by checking the function parameters for the exclusive flag.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-29 22:37:15 +01:00
David Howells 57494343cb rxrpc: Implement slow-start
Implement RxRPC slow-start, which is similar to RFC 5681 for TCP.  A
tracepoint is added to log the state of the congestion management algorithm
and the decisions it makes.

Notes:

 (1) Since we send fixed-size DATA packets (apart from the final packet in
     each phase), counters and calculations are in terms of packets rather
     than bytes.

 (2) The ACK packet carries the equivalent of TCP SACK.

 (3) The FLIGHT_SIZE calculation in RFC 5681 doesn't seem particularly
     suited to SACK of a small number of packets.  It seems that, almost
     inevitably, by the time three 'duplicate' ACKs have been seen, we have
     narrowed the loss down to one or two missing packets, and the
     FLIGHT_SIZE calculation ends up as 2.

 (4) In rxrpc_resend(), if there was no data that apparently needed
     retransmission, we transmit a PING ACK to ask the peer to tell us what
     its Rx window state is.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-24 23:49:46 +01:00
David Howells 0d967960d3 rxrpc: Schedule an ACK if the reply to a client call appears overdue
If we've sent all the request data in a client call but haven't seen any
sign of the reply data yet, schedule an ACK to be sent to the server to
find out if the reply data got lost.

If the server hasn't yet hard-ACK'd the request data, we send a PING ACK to
demand a response to find out whether we need to retransmit.

If the server says it has received all of the data, we send an IDLE ACK to
tell the server that we haven't received anything in the receive phase as
yet.

To make this work, a non-immediate PING ACK must carry a delay.  I've chosen
the same as the IDLE ACK for the moment.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-24 23:49:46 +01:00
David Howells 31a1b98950 rxrpc: Generate a summary of the ACK state for later use
Generate a summary of the Tx buffer packet state when an ACK is received
for use in a later patch that does congestion management.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-24 23:49:46 +01:00
David Howells df0562a72d rxrpc: Delay the resend timer to allow for nsec->jiffies conv error
When determining the resend timer value, we have a value in nsec but the
timer is in jiffies which may be a million or more times more coarse.
nsecs_to_jiffies() rounds down - which means that the resend timeout
expressed as jiffies is very likely earlier than the one expressed as
nanoseconds from which it was derived.

The problem is that rxrpc_resend() gets triggered by the timer, but can't
then find anything to resend yet.  It sets the timer again - but gets
kicked off immediately again and again until the nanosecond-based expiry
time is reached and we actually retransmit.

Fix this by adding 1 to the jiffies-based resend_at value to counteract the
rounding and make sure that the timer happens after the nanosecond-based
expiry is passed.

Alternatives would be to adjust the timestamp on the packets to align
with the jiffie scale or to switch back to using jiffie-timestamps.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-24 23:49:46 +01:00
David Howells dd7c1ee59a rxrpc: Reinitialise the call ACK and timer state for client reply phase
Clear the ACK reason, ACK timer and resend timer when entering the client
reply phase when the first DATA packet is received.  New ACKs will be
proposed once the data is queued.

The resend timer is no longer relevant and we need to cancel ACKs scheduled
to probe for a lost reply.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-24 23:49:46 +01:00
David Howells b69d94d799 rxrpc: Include the last reply DATA serial number in the final ACK
In a client call, include the serial number of the last DATA packet of the
reply in the final ACK.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-24 23:49:46 +01:00
David Howells a7056c5ba6 rxrpc: Send an immediate ACK if we fill in a hole
Send an immediate ACK if we fill in a hole in the buffer left by an
out-of-sequence packet.  This may allow the congestion management in the peer
to avoid a retransmission if packets got reordered on the wire.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-24 23:49:46 +01:00
David Howells 805b21b929 rxrpc: Send an ACK after every few DATA packets we receive
Send an ACK if we haven't sent one for the last two packets we've received.
This keeps the other end apprised of where we've got to - which is
important if they're doing slow-start.

We do this in recvmsg so that we can dispatch a packet directly without the
need to wake up the background thread.

This should possibly be made configurable in future.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-24 18:05:26 +01:00
David Howells c6672e3fe4 rxrpc: Add a tracepoint to log which packets will be retransmitted
Add a tracepoint to log in rxrpc_resend() which packets will be
retransmitted.  Note that if a positive ACK comes in whilst we have dropped
the lock to retransmit another packet, the actual retransmission may not
happen, though some of the effects will (such as altering the congestion
management).

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-23 15:49:19 +01:00
David Howells 9c7ad43444 rxrpc: Add tracepoint for ACK proposal
Add a tracepoint to log proposed ACKs, including whether the proposal is
used to update a pending ACK or is discarded in favour of an easlier,
higher priority ACK.

Whilst we're at it, get rid of the rxrpc_acks() function and access the
name array directly.  We do, however, need to validate the ACK reason
number given to trace_rxrpc_rx_ack() to make sure we don't overrun the
array.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-23 15:49:19 +01:00
David Howells 89b475abdb rxrpc: Add a tracepoint to log injected Rx packet loss
Add a tracepoint to log received packets that get discarded due to Rx
packet loss.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-23 15:49:19 +01:00
David Howells be832aecc5 rxrpc: Add data Tx tracepoint and adjust Tx ACK tracepoint
Add a tracepoint to log transmission of DATA packets (including loss
injection).

Adjust the ACK transmission tracepoint to include the packet serial number
and to line this up with the DATA transmission display.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-23 15:49:19 +01:00
David Howells fc7ab6d29a rxrpc: Add a tracepoint for the call timer
Add a tracepoint to log call timer initiation, setting and expiry.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-23 15:49:19 +01:00
David Howells b86e218e0d rxrpc: Don't call the tx_ack tracepoint if don't generate an ACK
rxrpc_send_call_packet() is invoking the tx_ack tracepoint before it checks
whether there's an ACK to transmit (another thread may jump in and transmit
it).

Fix this by only invoking the tracepoint if we get a valid ACK to transmit.

Further, only allocate a serial number if we're going to actually transmit
something.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-23 15:49:19 +01:00
David Howells 70790dbe3f rxrpc: Pass the last Tx packet marker in the annotation buffer
When the last packet of data to be transmitted on a call is queued, tx_top
is set and then the RXRPC_CALL_TX_LAST flag is set.  Unfortunately, this
leaves a race in the ACK processing side of things because the flag affects
the interpretation of tx_top and also allows us to start receiving reply
data before we've finished transmitting.

To fix this, make the following changes:

 (1) rxrpc_queue_packet() now sets a marker in the annotation buffer
     instead of setting the RXRPC_CALL_TX_LAST flag.

 (2) rxrpc_rotate_tx_window() detects the marker and sets the flag in the
     same context as the routines that use it.

 (3) rxrpc_end_tx_phase() is simplified to just shift the call state.
     The Tx window must have been rotated before calling to discard the
     last packet.

 (4) rxrpc_receiving_reply() is added to handle the arrival of the first
     DATA packet of a reply to a client call (which is an implicit ACK of
     the Tx phase).

 (5) The last part of rxrpc_input_ack() is reordered to perform Tx
     rotation, then soft-ACK application and then to end the phase if we've
     rotated the last packet.  In the event of a terminal ACK, the soft-ACK
     application will be skipped as nAcks should be 0.

 (6) rxrpc_input_ackall() now has to rotate as well as ending the phase.

In addition:

 (7) Alter the transmit tracepoint to log the rotation of the last packet.

 (8) Remove the no-longer relevant queue_reqack tracepoint note.  The
     ACK-REQUESTED packet header flag is now set as needed when we actually
     transmit the packet and may vary by retransmission.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-23 15:49:19 +01:00
David Howells 01a88f7f6b rxrpc: Fix call timer
Fix the call timer in the following ways:

 (1) If call->resend_at or call->ack_at are before or equal to the current
     time, then ignore that timeout.

 (2) If call->expire_at is before or equal to the current time, then don't
     set the timer at all (possibly we should queue the call).

 (3) Don't skip modifying the timer if timer_pending() is true.  This
     indicates that the timer is working, not that it has expired and is
     running/waiting to run its expiry handler.

Also call rxrpc_set_timer() to start the call timer going rather than
calling add_timer().

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-23 15:49:19 +01:00
David Howells be8aa33806 rxrpc: Fix accidental cancellation of scheduled resend by ACK parser
When rxrpc_input_soft_acks() is parsing the soft-ACKs from an ACK packet,
it updates the Tx packet annotations in the annotation buffer.  If a
soft-ACK is an ACK, then we overwrite unack'd, nak'd or to-be-retransmitted
states and that is fine; but if the soft-ACK is an NACK, we overwrite the
to-be-retransmitted with a nak - which isn't.

Instead, we need to let any scheduled retransmission stand if the packet
was NAK'd.

Note that we don't reissue a resend if the annotation is in the
to-be-retransmitted state because someone else must've scheduled the
resend already.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-23 15:35:45 +01:00
David Howells dfc3da4404 rxrpc: Need to start the resend timer on initial transmission
When a DATA packet has its initial transmission, we may need to start or
adjust the resend timer.  Without this we end up relying on being sent a
NACK to initiate the resend.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-23 14:05:12 +01:00
David Howells 98dafac569 rxrpc: Use before_eq() and friends to compare serial numbers
before_eq() and friends should be used to compare serial numbers (when not
checking for (non)equality) rather than casting to int, subtracting and
checking the result.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-23 14:05:08 +01:00
David Howells 90bd684ded rxrpc: Should be using ktime_add_ms() not ktime_add_ns()
ktime_add_ms() should be used to add the resend time (in ms) rather than
ktime_add_ns().

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-23 13:23:09 +01:00
David Howells c0d058c21c rxrpc: Make sure sendmsg() is woken on call completion
Make sure that sendmsg() gets woken up if the call it is waiting for
completes abnormally.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-23 13:23:09 +01:00
David Howells 9aff212bd6 rxrpc: Don't send an ACK at the end of service call response transmission
Don't send an IDLE ACK at the end of the transmission of the response to a
service call.  The service end resends DATA packets until the client sends an
ACK that hard-acks all the send data.  At that point, the call is complete.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-23 13:23:09 +01:00
David Howells b24d2891cf rxrpc: Preset timestamp on Tx sk_buffs
Set the timestamp on sk_buffs holding packets to be transmitted before
queueing them because the moment the packet is on the queue it can be seen
by the retransmission algorithm - which may see a completely random
timestamp.

If the retransmission algorithm sees such a timestamp, it may retransmit
the packet and, in future, tell the congestion management algorithm that
the retransmit timer expired.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-23 13:17:52 +01:00
David Howells fc943f6777 rxrpc: Reduce the number of PING ACKs sent
We don't want to send a PING ACK for every new incoming call as that just
adds to the network traffic.  Instead, we send a PING ACK to the first
three that we receive and then once per second thereafter.

This could probably be made adjustable in future.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-22 08:49:22 +01:00
David Howells 0d4b103c00 rxrpc: Reduce the number of ACK-Requests sent
Reduce the number of ACK-Requests we set on DATA packets that we're sending
to reduce network traffic.  We set the flag on odd-numbered DATA packets to
start off the RTT cache until we have at least three entries in it and then
probe once per second thereafter to keep it topped up.

This could be made tunable in future.

Note that from this point, the RXRPC_REQUEST_ACK flag is set on DATA
packets as we transmit them and not stored statically in the sk_buff.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-22 08:49:20 +01:00
David Howells 50235c4b5a rxrpc: Obtain RTT data by requesting ACKs on DATA packets
In addition to sending a PING ACK to gain RTT data, we can set the
RXRPC_REQUEST_ACK flag on a DATA packet and get a REQUESTED-ACK ACK.  The
ACK packet contains the serial number of the packet it is in response to,
so we can look through the Tx buffer for a matching DATA packet.

This requires that the data packets be stamped with the time of
transmission as a ktime rather than having the resend_at time in jiffies.

This further requires the resend code to do the resend determination in
ktimes and convert to jiffies to set the timer.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-22 08:21:24 +01:00
David Howells 7aa51da7c8 rxrpc: Expedite ping response transmission
Expedite the transmission of a response to a PING ACK by sending it from
sendmsg if one is pending.  We're most likely to see a PING ACK during the
client call Tx phase as the other side may use it to determine a number of
parameters, such as the client's receive window size, the RTT and whether
the client is doing slow start (similar to RFC5681).

If we don't expedite it, it's left to the background processing thread to
transmit.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-22 08:21:24 +01:00
David Howells 8e83134db4 rxrpc: Send pings to get RTT data
Send a PING ACK packet to the peer when we get a new incoming call from a
peer we don't have a record for.  The PING RESPONSE ACK packet will tell us
the following about the peer:

 (1) its receive window size

 (2) its MTU sizes

 (3) its support for jumbo DATA packets

 (4) if it supports slow start (similar to RFC 5681)

 (5) an estimate of the RTT

This is necessary because the peer won't normally send us an ACK until it
gets to the Rx phase and we send it a packet, but we would like to know
some of this information before we start sending packets.

A pair of tracepoints are added so that RTT determination can be observed.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-22 08:21:24 +01:00
David Howells cf1a6474f8 rxrpc: Add per-peer RTT tracker
Add a function to track the average RTT for a peer.  Sources of RTT data
will be added in subsequent patches.

The RTT data will be useful in the future for determining resend timeouts
and for handling the slow-start part of the Rx protocol.

Also add a pair of tracepoints, one to log transmissions to elicit a
response for RTT purposes and one to log responses that contribute RTT
data.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-22 01:26:25 +01:00
David Howells f07373ead4 rxrpc: Add re-sent Tx annotation
Add a Tx-phase annotation for packet buffers to indicate that a buffer has
already been retransmitted.  This will be used by future congestion
management.  Re-retransmissions of a packet don't affect the congestion
window managment in the same way as initial retransmissions.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-22 01:23:50 +01:00
David Howells 5a924b8951 rxrpc: Don't store the rxrpc header in the Tx queue sk_buffs
Don't store the rxrpc protocol header in sk_buffs on the transmit queue,
but rather generate it on the fly and pass it to kernel_sendmsg() as a
separate iov.  This reduces the amount of storage required.

Note that the security header is still stored in the sk_buff as it may get
encrypted along with the data (and doesn't change with each transmission).

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-22 01:23:50 +01:00
David Howells 8a681c3605 rxrpc: Add config to inject packet loss
Add a configuration option to inject packet loss by discarding
approximately every 8th packet received and approximately every 8th DATA
packet transmitted.

Note that no locking is used, but it shouldn't really matter.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-17 11:24:04 +01:00
David Howells 71f3ca408f rxrpc: Improve skb tracing
Improve sk_buff tracing within AF_RXRPC by the following means:

 (1) Use an enum to note the event type rather than plain integers and use
     an array of event names rather than a big multi ?: list.

 (2) Distinguish Rx from Tx packets and account them separately.  This
     requires the call phase to be tracked so that we know what we might
     find in rxtx_buffer[].

 (3) Add a parameter to rxrpc_{new,see,get,free}_skb() to indicate the
     event type.

 (4) A pair of 'rotate' events are added to indicate packets that are about
     to be rotated out of the Rx and Tx windows.

 (5) A pair of 'lost' events are added, along with rxrpc_lose_skb() for
     packet loss injection recording.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-17 11:24:04 +01:00
David Howells ba39f3a0ed rxrpc: Remove printks from rxrpc_recvmsg_data() to fix uninit var
Remove _enter/_debug/_leave calls from rxrpc_recvmsg_data() of which one
uses an uninitialised variable.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-17 11:24:04 +01:00
David Howells 849979051c rxrpc: Add a tracepoint to follow what recvmsg does
Add a tracepoint to follow what recvmsg does within AF_RXRPC.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-17 11:24:03 +01:00
David Howells 58dc63c998 rxrpc: Add a tracepoint to follow packets in the Rx buffer
Add a tracepoint to follow the life of packets that get added to a call's
receive buffer.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-17 11:24:03 +01:00
David Howells f3639df2d9 rxrpc: Add a tracepoint to log ACK transmission
Add a tracepoint to log information about ACK transmission.

Signed-off-by: David Howels <dhowells@redhat.com>
2016-09-17 11:24:03 +01:00
David Howells ec71eb9ada rxrpc: Add a tracepoint to log received ACK packets
Add a tracepoint to log information from received ACK packets.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-17 11:24:03 +01:00
David Howells a124fe3ee5 rxrpc: Add a tracepoint to follow the life of a packet in the Tx buffer
Add a tracepoint to follow the insertion of a packet into the transmit
buffer, its transmission and its rotation out of the buffer.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-17 11:24:03 +01:00
David Howells 363deeab6d rxrpc: Add connection tracepoint and client conn state tracepoint
Add a pair of tracepoints, one to track rxrpc_connection struct ref
counting and the other to track the client connection cache state.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-17 11:24:03 +01:00
David Howells a84a46d730 rxrpc: Add some additional call tracing
Add additional call tracepoint points for noting call-connected,
call-released and connection-failed events.

Also fix one tracepoint that was using an integer instead of the
corresponding enum value as the point type.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-17 11:24:03 +01:00
David Howells a3868bfc8d rxrpc: Print the packet type name in the Rx packet trace
Print a symbolic packet type name for each valid received packet in the
trace output, not just a number.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-17 11:24:03 +01:00
David Howells 182f505624 rxrpc: Fix the basic transmit DATA packet content size at 1412 bytes
Fix the basic transmit DATA packet content size at 1412 bytes so that they
can be arbitrarily assembled into jumbo packets.

In the future, I'm thinking of moving to keeping a jumbo packet header at
the beginning of each packet in the Tx queue and creating the packet header
on the spot when kernel_sendmsg() is invoked.  That way, jumbo packets can
be assembled on the spur of the moment for (re-)transmission.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-17 10:54:32 +01:00
David Howells 2311e327cd rxrpc: Be consistent about switch value in rxrpc_send_call_packet()
rxrpc_send_call_packet() should use type in both its switch-statements
rather than using pkt->whdr.type.  This might give the compiler an easier
job of uninitialised variable checking.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-17 10:54:21 +01:00
David Howells 27d0fc431c rxrpc: Don't transmit an ACK if there's no reason set
Don't transmit an ACK if call->ackr_reason in unset.  There's the
possibility of a race between recvmsg() sending an ACK and the background
processing thread trying to send the same one.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-17 10:53:55 +01:00
David Howells dfa7d92040 rxrpc: Fix retransmission algorithm
Make the retransmission algorithm use for-loops instead of do-loops and
move the counter increments into the for-statement increment slots.

Though the do-loops are slighly more efficient since there will be at least
one pass through the each loop, the counter increments are harder to get
right as the continue-statements skip them.

Without this, if there are any positive acks within the loop, the do-loop
will cycle forever because the counter increment is never done.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-17 10:53:21 +01:00
David Howells d01dc4c3c1 rxrpc: Fix the parsing of soft-ACKs
The soft-ACK parser doesn't increment the pointer into the soft-ACK list,
resulting in the first ACK/NACK value being applied to all the relevant
packets in the Tx queue.  This has the potential to miss retransmissions
and cause excessive retransmissions.

Fix this by incrementing the pointer.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-17 10:53:21 +01:00
David Howells 78883793f8 rxrpc: Fix unexposed client conn release
If the last call on a client connection is release after the connection has
had a bunch of calls allocated but before any DATA packets are sent (so
that it's not yet marked RXRPC_CONN_EXPOSED), an assertion will happen in
rxrpc_disconnect_client_call().

	af_rxrpc: Assertion failed - 1(0x1) >= 2(0x2) is false
	------------[ cut here ]------------
	kernel BUG at ../net/rxrpc/conn_client.c:753!

This is because it's expecting the conn to have been exposed and to have 2
or more refs - but this isn't necessarily the case.

Simply remove the assertion.  This allows the conn to be moved into the
inactive state and deleted if it isn't resurrected before the final put is
called.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-17 10:53:21 +01:00
David Howells 357f5ef646 rxrpc: Call rxrpc_release_call() on error in rxrpc_new_client_call()
Call rxrpc_release_call() on getting an error in rxrpc_new_client_call()
rather than trying to do the cleanup ourselves.  This isn't a problem,
provided we set RXRPC_CALL_HAS_USERID only if we actually add the call to
the calls tree as cleanup code fragments that would otherwise cause
problems are conditional.

Without this, we miss some of the cleanup.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-17 10:53:21 +01:00
David Howells 66d58af7f4 rxrpc: Fix the putting of client connections
In rxrpc_put_one_client_conn(), if a connection has RXRPC_CONN_COUNTED set
on it, then it's accounted for in rxrpc_nr_client_conns and may be on
various lists - and this is cleaned up correctly.

However, if the connection doesn't have RXRPC_CONN_COUNTED set on it, then
the put routine returns rather than just skipping the extra bit of cleanup.

Fix this by making the extra bit of clean up conditional instead and always
killing off the connection.

This manifests itself as connections with a zero usage count hanging around
in /proc/net/rxrpc_conns because the connection allocated, but discarded,
due to a race with another process that set up a parallel connection, which
was then shared instead.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-17 10:53:20 +01:00
David Howells 0360da6db7 rxrpc: Purge the to_be_accepted queue on socket release
Purge the queue of to_be_accepted calls on socket release.  Note that
purging sock_calls doesn't release the ref owned by to_be_accepted.

Probably the sock_calls list is redundant given a purges of the recvmsg_q,
the to_be_accepted queue and the calls tree.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-17 10:51:54 +01:00
David Howells e6f3afb3fc rxrpc: Record calls that need to be accepted
Record calls that need to be accepted using sk_acceptq_added() otherwise
the backlog counter goes negative because sk_acceptq_removed() is called.
This causes the preallocator to malfunction.

Calls that are preaccepted by AFS within the kernel aren't affected by
this.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-17 10:51:54 +01:00
David Howells 816c9fce12 rxrpc: Fix handling of the last packet in rxrpc_recvmsg_data()
The code for determining the last packet in rxrpc_recvmsg_data() has been
using the RXRPC_CALL_RX_LAST flag to determine if the rx_top pointer points
to the last packet or not.  This isn't a good idea, however, as the input
code may be running simultaneously on another CPU and that sets the flag
*before* updating the top pointer.

Fix this by the following means:

 (1) Restrict the use of RXRPC_CALL_RX_LAST to the input routines only.
     There's otherwise a synchronisation problem between detecting the flag
     and checking tx_top.  This could probably be dealt with by appropriate
     application of memory barriers, but there's a simpler way.

 (2) Set RXRPC_CALL_RX_LAST after setting rx_top.

 (3) Make rxrpc_rotate_rx_window() consult the flags header field of the
     DATA packet it's about to discard to see if that was the last packet.
     Use this as the basis for ending the Rx phase.  This shouldn't be a
     problem because the recvmsg side of things is guaranteed to see the
     packets in order.

 (4) Make rxrpc_recvmsg_data() return 1 to indicate the end of the data if:

     (a) the packet it has just processed is marked as RXRPC_LAST_PACKET

     (b) the call's Rx phase has been ended.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-17 10:51:54 +01:00
David Howells 2e2ea51dec rxrpc: Check the return value of rxrpc_locate_data()
Check the return value of rxrpc_locate_data() in rxrpc_recvmsg_data().

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-17 10:50:49 +01:00
David Howells 4b22457c06 rxrpc: Move the check of rx_pkt_offset from rxrpc_locate_data() to caller
Move the check of rx_pkt_offset from rxrpc_locate_data() to the caller,
rxrpc_recvmsg_data(), so that it's more clear what's going on there.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-17 10:50:48 +01:00
David Howells fabf920180 rxrpc: Remove some whitespace.
Remove a tab that's on a line that should otherwise be blank.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-17 10:50:15 +01:00
David Howells d19127473a rxrpc: Make IPv6 support conditional on CONFIG_IPV6
Add CONFIG_AF_RXRPC_IPV6 and make the IPv6 support code conditional on it.
This is then made conditional on CONFIG_IPV6.

Without this, the following can be seen:

   net/built-in.o: In function `rxrpc_init_peer':
>> peer_object.c:(.text+0x18c3c8): undefined reference to `ip6_route_output_flags'

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-09-17 03:58:45 -04:00
David Howells 75b54cb57c rxrpc: Add IPv6 support
Add IPv6 support to AF_RXRPC.  With this, AF_RXRPC sockets can be created:

	service = socket(AF_RXRPC, SOCK_DGRAM, PF_INET6);

instead of:

	service = socket(AF_RXRPC, SOCK_DGRAM, PF_INET);

The AFS filesystem doesn't support IPv6 at the moment, though, since that
requires upgrades to some of the RPC calls.

Note that a good portion of this patch is replacing "%pI4:%u" in print
statements with "%pISpc" which is able to handle both protocols and print
the port.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-13 23:09:13 +01:00
David Howells 1c2bc7b948 rxrpc: Use rxrpc_extract_addr_from_skb() rather than doing this manually
There are two places that want to transmit a packet in response to one just
received and manually pick the address to reply to out of the sk_buff.
Make them use rxrpc_extract_addr_from_skb() instead so that IPv6 is handled
automatically.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-13 23:09:13 +01:00
David Howells aaa31cbc66 rxrpc: Don't specify protocol to when creating transport socket
Pass 0 as the protocol argument when creating the transport socket rather
than IPPROTO_UDP.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-13 23:09:13 +01:00
David Howells cd5892c756 rxrpc: Create an address for sendmsg() to bind unbound socket with
Create an address for sendmsg() to bind unbound socket with rather than
using a completely blank address otherwise the transport socket creation
will fail because it will try to use address family 0.

We use the address family specified in the protocol argument when the
AF_RXRPC socket was created and SOCK_DGRAM as the default.  For anything
else, bind() must be used.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-13 23:09:13 +01:00
David Howells 75e4212639 rxrpc: Correctly initialise, limit and transmit call->rx_winsize
call->rx_winsize should be initialised to the sysctl setting and the sysctl
setting should be limited to the maximum we want to permit.  Further, we
need to place this in the ACK info instead of the sysctl setting.

Furthermore, discard the idea of accepting the subpackets of a jumbo packet
that lie beyond the receive window when the first packet of the jumbo is
within the window.  Just discard the excess subpackets instead.  This
allows the receive window to be opened up right to the buffer size less one
for the dead slot.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-13 22:38:45 +01:00
David Howells 3432a757b1 rxrpc: Fix prealloc refcounting
The preallocated call buffer holds a ref on the calls within that buffer.
The ref was being released in the wrong place - it worked okay for incoming
calls to the AFS cache manager service, but doesn't work right for incoming
calls to a userspace service.

Instead of releasing an extra ref service calls in rxrpc_release_call(),
the ref needs to be released during the acceptance/rejectance process.  To
this end:

 (1) The prealloc ref is now normally released during
     rxrpc_new_incoming_call().

 (2) For preallocated kernel API calls, the kernel API's ref needs to be
     released when the call is discarded on socket close.

 (3) We shouldn't take a second ref in rxrpc_accept_call().

 (4) rxrpc_recvmsg_new_call() needs to get a ref of its own when it adds
     the call to the to_be_accepted socket queue.

In doing (4) above, we would prefer not to put the call's refcount down to
0 as that entails doing cleanup in softirq context, but it's unlikely as
there are several refs held elsewhere, at least one of which must be put by
someone in process context calling rxrpc_release_call().  However, it's not
a problem if we do have to do that.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-13 22:38:37 +01:00
David Howells cbd00891de rxrpc: Adjust the call ref tracepoint to show kernel API refs
Adjust the call ref tracepoint to show references held on a call by the
kernel API separately as much as possible and add an additional trace to at
the allocation point from the preallocation buffer for an incoming call.

Note that this doesn't show the allocation of a client call for the kernel
separately at the moment.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-13 22:38:30 +01:00
David Howells 01fd074224 rxrpc: Allow tx_winsize to grow in response to an ACK
Allow tx_winsize to grow when the ACK info packet shows a larger receive
window at the other end rather than only permitting it to shrink.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-13 22:38:24 +01:00
David Howells 89a80ed4c0 rxrpc: Use skb->len not skb->data_len
skb->len should be used rather than skb->data_len when referring to the
amount of data in a packet.  This will only cause a malfunction in the
following cases:

 (1) We receive a jumbo packet (validation and splitting both are wrong).

 (2) We see if there's extra ACK info in an ACK packet (we think it's not
     there and just ignore it).

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-13 22:36:22 +01:00
David Howells b25de36053 rxrpc: Add missing unlock in rxrpc_call_accept()
Add a missing unlock in rxrpc_call_accept() in the path taken if there's no
call to wake up.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-13 22:36:22 +01:00
David Howells 33b603fda8 rxrpc: Requeue call for recvmsg if more data
rxrpc_recvmsg() needs to make sure that the call it has just been
processing gets requeued for further attention if the buffer has been
filled and there's more data to be consumed.  The softirq producer only
queues the call and wakes the socket if it fills the first slot in the
window, so userspace might end up sleeping forever otherwise, despite there
being data available.

This is not a problem provided the userspace buffer is big enough or it
empties the buffer completely before more data comes in.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-13 22:36:21 +01:00
David Howells 91c2c7b656 rxrpc: The IDLE ACK packet should use rxrpc_idle_ack_delay
The IDLE ACK packet should use the rxrpc_idle_ack_delay setting when the
timer is set for it.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-13 22:36:21 +01:00
David Howells bc4abfcf51 rxrpc: Add missing wakeup on Tx window rotation
We need to wake up the sender when Tx window rotation due to an incoming
ACK makes space in the buffer otherwise the sender is liable to just hang
endlessly.

This problem isn't noticeable if the Tx phase transfers no more than will
fit in a single window or the Tx window rotates fast enough that it doesn't
get full.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-13 22:36:21 +01:00
David Howells 08a39685a7 rxrpc: Make sure we initialise the peer hash key
Peer records created for incoming connections weren't getting their hash
key set.  This meant that incoming calls wouldn't see more than one DATA
packet - which is not a problem for AFS CM calls with small request data
blobs.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-13 22:36:21 +01:00
David Howells 248f219cb8 rxrpc: Rewrite the data and ack handling code
Rewrite the data and ack handling code such that:

 (1) Parsing of received ACK and ABORT packets and the distribution and the
     filing of DATA packets happens entirely within the data_ready context
     called from the UDP socket.  This allows us to process and discard ACK
     and ABORT packets much more quickly (they're no longer stashed on a
     queue for a background thread to process).

 (2) We avoid calling skb_clone(), pskb_pull() and pskb_trim().  We instead
     keep track of the offset and length of the content of each packet in
     the sk_buff metadata.  This means we don't do any allocation in the
     receive path.

 (3) Jumbo DATA packet parsing is now done in data_ready context.  Rather
     than cloning the packet once for each subpacket and pulling/trimming
     it, we file the packet multiple times with an annotation for each
     indicating which subpacket is there.  From that we can directly
     calculate the offset and length.

 (4) A call's receive queue can be accessed without taking locks (memory
     barriers do have to be used, though).

 (5) Incoming calls are set up from preallocated resources and immediately
     made live.  They can than have packets queued upon them and ACKs
     generated.  If insufficient resources exist, DATA packet #1 is given a
     BUSY reply and other DATA packets are discarded).

 (6) sk_buffs no longer take a ref on their parent call.

To make this work, the following changes are made:

 (1) Each call's receive buffer is now a circular buffer of sk_buff
     pointers (rxtx_buffer) rather than a number of sk_buff_heads spread
     between the call and the socket.  This permits each sk_buff to be in
     the buffer multiple times.  The receive buffer is reused for the
     transmit buffer.

 (2) A circular buffer of annotations (rxtx_annotations) is kept parallel
     to the data buffer.  Transmission phase annotations indicate whether a
     buffered packet has been ACK'd or not and whether it needs
     retransmission.

     Receive phase annotations indicate whether a slot holds a whole packet
     or a jumbo subpacket and, if the latter, which subpacket.  They also
     note whether the packet has been decrypted in place.

 (3) DATA packet window tracking is much simplified.  Each phase has just
     two numbers representing the window (rx_hard_ack/rx_top and
     tx_hard_ack/tx_top).

     The hard_ack number is the sequence number before base of the window,
     representing the last packet the other side says it has consumed.
     hard_ack starts from 0 and the first packet is sequence number 1.

     The top number is the sequence number of the highest-numbered packet
     residing in the buffer.  Packets between hard_ack+1 and top are
     soft-ACK'd to indicate they've been received, but not yet consumed.

     Four macros, before(), before_eq(), after() and after_eq() are added
     to compare sequence numbers within the window.  This allows for the
     top of the window to wrap when the hard-ack sequence number gets close
     to the limit.

     Two flags, RXRPC_CALL_RX_LAST and RXRPC_CALL_TX_LAST, are added also
     to indicate when rx_top and tx_top point at the packets with the
     LAST_PACKET bit set, indicating the end of the phase.

 (4) Calls are queued on the socket 'receive queue' rather than packets.
     This means that we don't need have to invent dummy packets to queue to
     indicate abnormal/terminal states and we don't have to keep metadata
     packets (such as ABORTs) around

 (5) The offset and length of a (sub)packet's content are now passed to
     the verify_packet security op.  This is currently expected to decrypt
     the packet in place and validate it.

     However, there's now nowhere to store the revised offset and length of
     the actual data within the decrypted blob (there may be a header and
     padding to skip) because an sk_buff may represent multiple packets, so
     a locate_data security op is added to retrieve these details from the
     sk_buff content when needed.

 (6) recvmsg() now has to handle jumbo subpackets, where each subpacket is
     individually secured and needs to be individually decrypted.  The code
     to do this is broken out into rxrpc_recvmsg_data() and shared with the
     kernel API.  It now iterates over the call's receive buffer rather
     than walking the socket receive queue.

Additional changes:

 (1) The timers are condensed to a single timer that is set for the soonest
     of three timeouts (delayed ACK generation, DATA retransmission and
     call lifespan).

 (2) Transmission of ACK and ABORT packets is effected immediately from
     process-context socket ops/kernel API calls that cause them instead of
     them being punted off to a background work item.  The data_ready
     handler still has to defer to the background, though.

 (3) A shutdown op is added to the AF_RXRPC socket so that the AFS
     filesystem can shut down the socket and flush its own work items
     before closing the socket to deal with any in-progress service calls.

Future additional changes that will need to be considered:

 (1) Make sure that a call doesn't hog the front of the queue by receiving
     data from the network as fast as userspace is consuming it to the
     exclusion of other calls.

 (2) Transmit delayed ACKs from within recvmsg() when we've consumed
     sufficiently more packets to avoid the background work item needing to
     run.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-08 11:10:12 +01:00
David Howells 00e907127e rxrpc: Preallocate peers, conns and calls for incoming service requests
Make it possible for the data_ready handler called from the UDP transport
socket to completely instantiate an rxrpc_call structure and make it
immediately live by preallocating all the memory it might need.  The idea
is to cut out the background thread usage as much as possible.

[Note that the preallocated structs are not actually used in this patch -
 that will be done in a future patch.]

If insufficient resources are available in the preallocation buffers, it
will be possible to discard the DATA packet in the data_ready handler or
schedule a BUSY packet without the need to schedule an attempt at
allocation in a background thread.

To this end:

 (1) Preallocate rxrpc_peer, rxrpc_connection and rxrpc_call structs to a
     maximum number each of the listen backlog size.  The backlog size is
     limited to a maxmimum of 32.  Only this many of each can be in the
     preallocation buffer.

 (2) For userspace sockets, the preallocation is charged initially by
     listen() and will be recharged by accepting or rejecting pending
     new incoming calls.

 (3) For kernel services {,re,dis}charging of the preallocation buffers is
     handled manually.  Two notifier callbacks have to be provided before
     kernel_listen() is invoked:

     (a) An indication that a new call has been instantiated.  This can be
     	 used to trigger background recharging.

     (b) An indication that a call is being discarded.  This is used when
     	 the socket is being released.

     A function, rxrpc_kernel_charge_accept() is called by the kernel
     service to preallocate a single call.  It should be passed the user ID
     to be used for that call and a callback to associate the rxrpc call
     with the kernel service's side of the ID.

 (4) Discard the preallocation when the socket is closed.

 (5) Temporarily bump the refcount on the call allocated in
     rxrpc_incoming_call() so that rxrpc_release_call() can ditch the
     preallocation ref on service calls unconditionally.  This will no
     longer be necessary once the preallocation is used.

Note that this does not yet control the number of active service calls on a
client - that will come in a later patch.

A future development would be to provide a setsockopt() call that allows a
userspace server to manually charge the preallocation buffer.  This would
allow user call IDs to be provided in advance and the awkward manual accept
stage to be bypassed.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-08 11:10:12 +01:00
David Howells 49e19ec7d3 rxrpc: Add tracepoints to record received packets and end of data_ready
Add two tracepoints:

 (1) Record the RxRPC protocol header of packets retrieved from the UDP
     socket by the data_ready handler.

 (2) Record the outcome of the data_ready handler.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-08 11:10:12 +01:00
David Howells 2ab27215ea rxrpc: Remove skb_count from struct rxrpc_call
Remove the sk_buff count from the rxrpc_call struct as it's less useful
once we stop queueing sk_buffs.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-08 11:10:12 +01:00
David Howells de8d6c7401 rxrpc: Convert rxrpc_local::services to an hlist
Convert the rxrpc_local::services list to an hlist so that it can be
accessed under RCU conditions more readily.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-08 11:10:11 +01:00
David Howells cf13258fd4 rxrpc: Fix ASSERTCMP and ASSERTIFCMP to handle signed values
Fix ASSERTCMP and ASSERTIFCMP to be able to handle signed values by casting
both parameters to the type of the first before comparing.  Without this,
both values are cast to unsigned long, which means that checks for values
less than zero don't work.

The downside of this is that the state enum values in struct rxrpc_call and
struct rxrpc_connection can't be bitfields as __typeof__ can't handle them.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-08 11:10:11 +01:00
David Howells 5a42976d4f rxrpc: Add tracepoint for working out where aborts happen
Add a tracepoint for working out where local aborts happen.  Each
tracepoint call is labelled with a 3-letter code so that they can be
distinguished - and the DATA sequence number is added too where available.

rxrpc_kernel_abort_call() also takes a 3-letter code so that AFS can
indicate the circumstances when it aborts a call.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-07 16:34:40 +01:00
David Howells e8d6bbb05a rxrpc: Fix returns of call completion helpers
rxrpc_set_call_completion() returns bool, not int, so the ret variable
should match this.

rxrpc_call_completed() and __rxrpc_call_completed() should return the value
of rxrpc_set_call_completion().

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-07 16:34:30 +01:00
David Howells 8d94aa381d rxrpc: Calls shouldn't hold socket refs
rxrpc calls shouldn't hold refs on the sock struct.  This was done so that
the socket wouldn't go away whilst the call was in progress, such that the
call could reach the socket's queues.

However, we can mark the socket as requiring an RCU release and rely on the
RCU read lock.

To make this work, we do:

 (1) rxrpc_release_call() removes the call's call user ID.  This is now
     only called from socket operations and not from the call processor:

	rxrpc_accept_call() / rxrpc_kernel_accept_call()
	rxrpc_reject_call() / rxrpc_kernel_reject_call()
	rxrpc_kernel_end_call()
	rxrpc_release_calls_on_socket()
	rxrpc_recvmsg()

     Though it is also called in the cleanup path of
     rxrpc_accept_incoming_call() before we assign a user ID.

 (2) Pass the socket pointer into rxrpc_release_call() rather than getting
     it from the call so that we can get rid of uninitialised calls.

 (3) Fix call processor queueing to pass a ref to the work queue and to
     release that ref at the end of the processor function (or to pass it
     back to the work queue if we have to requeue).

 (4) Skip out of the call processor function asap if the call is complete
     and don't requeue it if the call is complete.

 (5) Clean up the call immediately that the refcount reaches 0 rather than
     trying to defer it.  Actual deallocation is deferred to RCU, however.

 (6) Don't hold socket refs for allocated calls.

 (7) Use the RCU read lock when queueing a message on a socket and treat
     the call's socket pointer according to RCU rules and check it for
     NULL.

     We also need to use the RCU read lock when viewing a call through
     procfs.

 (8) Transmit the final ACK/ABORT to a client call in rxrpc_release_call()
     if this hasn't been done yet so that we can then disconnect the call.
     Once the call is disconnected, it won't have any access to the
     connection struct and the UDP socket for the call work processor to be
     able to send the ACK.  Terminal retransmission will be handled by the
     connection processor.

 (9) Release all calls immediately on the closing of a socket rather than
     trying to defer this.  Incomplete calls will be aborted.

The call refcount model is much simplified.  Refs are held on the call by:

 (1) A socket's user ID tree.

 (2) A socket's incoming call secureq and acceptq.

 (3) A kernel service that has a call in progress.

 (4) A queued call work processor.  We have to take care to put any call
     that we failed to queue.

 (5) sk_buffs on a socket's receive queue.  A future patch will get rid of
     this.

Whilst we're at it, we can do:

 (1) Get rid of the RXRPC_CALL_EV_RELEASE event.  Release is now done
     entirely from the socket routines and never from the call's processor.

 (2) Get rid of the RXRPC_CALL_DEAD state.  Calls now end in the
     RXRPC_CALL_COMPLETE state.

 (3) Get rid of the rxrpc_call::destroyer work item.  Calls are now torn
     down when their refcount reaches 0 and then handed over to RCU for
     final cleanup.

 (4) Get rid of the rxrpc_call::deadspan timer.  Calls are cleaned up
     immediately they're finished with and don't hang around.
     Post-completion retransmission is handled by the connection processor
     once the call is disconnected.

 (5) Get rid of the dead call expiry setting as there's no longer a timer
     to set.

 (6) rxrpc_destroy_all_calls() can just check that the call list is empty.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-07 15:33:20 +01:00
David Howells 6543ac5235 rxrpc: Use rxrpc_is_service_call() rather than rxrpc_conn_is_service()
Use rxrpc_is_service_call() rather than rxrpc_conn_is_service() if the call
is available just in case call->conn is NULL.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-07 15:30:22 +01:00
David Howells 8b7fac50ab rxrpc: Pass the connection pointer to rxrpc_post_packet_to_call()
Pass the connection pointer to rxrpc_post_packet_to_call() as the call
might get disconnected whilst we're looking at it, but the connection
pointer determined by rxrpc_data_read() is guaranteed by RCU for the
duration of the call.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-07 15:30:22 +01:00
David Howells 278ac0cdd5 rxrpc: Cache the security index in the rxrpc_call struct
Cache the security index in the rxrpc_call struct so that we can get at it
even when the call has been disconnected and the connection pointer
cleared.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-07 15:30:22 +01:00
David Howells f4fdb3525b rxrpc: Use call->peer rather than call->conn->params.peer
Use call->peer rather than call->conn->params.peer to avoid the possibility
of call->conn being NULL and, whilst we're at it, check it for NULL before we
access it.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-07 15:30:22 +01:00
David Howells fff72429c2 rxrpc: Improve the call tracking tracepoint
Improve the call tracking tracepoint by showing more differentiation
between some of the put and get events, including:

  (1) Getting and putting refs for the socket call user ID tree.

  (2) Getting and putting refs for queueing and failing to queue the call
      processor work item.

Note that these aren't necessarily used in this patch, but will be taken
advantage of in future patches.

An enum is added for the event subtype numbers rather than coding them
directly as decimal numbers and a table of 3-letter strings is provided
rather than a sequence of ?: operators.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-07 15:30:22 +01:00
David Howells e796cb4192 rxrpc: Delete unused rxrpc_kernel_free_skb()
Delete rxrpc_kernel_free_skb() as it's unused.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-07 14:43:43 +01:00
David Howells 71a17de307 rxrpc: Whitespace cleanup
Remove some whitespace.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-07 14:43:39 +01:00
David Howells 3dc20f090d rxrpc Move enum rxrpc_command to sendmsg.c
Move enum rxrpc_command to sendmsg.c as it's now only used in that file.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-04 21:41:39 +01:00
David Howells df423a4af1 rxrpc: Rearrange net/rxrpc/sendmsg.c
Rearrange net/rxrpc/sendmsg.c to be in a more logical order.  This makes it
easier to follow and eliminates forward declarations.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-04 21:41:39 +01:00
David Howells 0b58b8a18b rxrpc: Split sendmsg from packet transmission code
Split the sendmsg code from the packet transmission code (mostly to be
found in output.c).

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-04 21:41:39 +01:00
David Howells 090f85deb6 rxrpc: Don't change the epoch
It seems the local epoch should only be changed on boot, so remove the code
that changes it for client connections.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-04 21:41:39 +01:00
David Howells 5f2d9c4438 rxrpc: Randomise epoch and starting client conn ID values
Create a random epoch value rather than a time-based one on startup and set
the top bit to indicate that this is the case.

Also create a random starting client connection ID value.  This will be
incremented from here as new client connections are created.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-04 21:41:39 +01:00
David Howells af338a9ea6 rxrpc: The client call state must be changed before attachment to conn
We must set the client call state to RXRPC_CALL_CLIENT_SEND_REQUEST before
attaching the call to the connection struct, not after, as it's liable to
receive errors and conn aborts as soon as the assignment is made - and
these will cause its state to be changed outside of the initiating thread's
control.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-04 13:10:10 +01:00
David Howells 00b5407e42 rxrpc: Fix uninitialised variable warning
Fix the following uninitialised variable warning:

../net/rxrpc/call_event.c: In function 'rxrpc_process_call':
../net/rxrpc/call_event.c:879:58: warning: 'error' may be used uninitialized in this function [-Wmaybe-uninitialized]
    _debug("post net error %d", error);
                                                          ^

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-02 22:39:44 +01:00
Arnd Bergmann 30787a4170 rxrpc: fix undefined behavior in rxrpc_mark_call_released
gcc -Wmaybe-initialized correctly points out a newly introduced bug
through which we can end up calling rxrpc_queue_call() for a dead
connection:

net/rxrpc/call_object.c: In function 'rxrpc_mark_call_released':
net/rxrpc/call_object.c:600:5: error: 'sched' may be used uninitialized in this function [-Werror=maybe-uninitialized]

This sets the 'sched' variable to zero to restore the previous
behavior.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: f5c17aaeb2 ("rxrpc: Calls should only have one terminal state")
Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-02 22:39:44 +01:00
David Howells d001648ec7 rxrpc: Don't expose skbs to in-kernel users [ver #2]
Don't expose skbs to in-kernel users, such as the AFS filesystem, but
instead provide a notification hook the indicates that a call needs
attention and another that indicates that there's a new call to be
collected.

This makes the following possibilities more achievable:

 (1) Call refcounting can be made simpler if skbs don't hold refs to calls.

 (2) skbs referring to non-data events will be able to be freed much sooner
     rather than being queued for AFS to pick up as rxrpc_kernel_recv_data
     will be able to consult the call state.

 (3) We can shortcut the receive phase when a call is remotely aborted
     because we don't have to go through all the packets to get to the one
     cancelling the operation.

 (4) It makes it easier to do encryption/decryption directly between AFS's
     buffers and sk_buffs.

 (5) Encryption/decryption can more easily be done in the AFS's thread
     contexts - usually that of the userspace process that issued a syscall
     - rather than in one of rxrpc's background threads on a workqueue.

 (6) AFS will be able to wait synchronously on a call inside AF_RXRPC.

To make this work, the following interface function has been added:

     int rxrpc_kernel_recv_data(
		struct socket *sock, struct rxrpc_call *call,
		void *buffer, size_t bufsize, size_t *_offset,
		bool want_more, u32 *_abort_code);

This is the recvmsg equivalent.  It allows the caller to find out about the
state of a specific call and to transfer received data into a buffer
piecemeal.

afs_extract_data() and rxrpc_kernel_recv_data() now do all the extraction
logic between them.  They don't wait synchronously yet because the socket
lock needs to be dealt with.

Five interface functions have been removed:

	rxrpc_kernel_is_data_last()
    	rxrpc_kernel_get_abort_code()
    	rxrpc_kernel_get_error_number()
    	rxrpc_kernel_free_skb()
    	rxrpc_kernel_data_consumed()

As a temporary hack, sk_buffs going to an in-kernel call are queued on the
rxrpc_call struct (->knlrecv_queue) rather than being handed over to the
in-kernel user.  To process the queue internally, a temporary function,
temp_deliver_data() has been added.  This will be replaced with common code
between the rxrpc_recvmsg() path and the kernel_rxrpc_recv_data() path in a
future patch.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-09-01 16:43:27 -07:00
David Howells 4de48af663 rxrpc: Pass struct socket * to more rxrpc kernel interface functions
Pass struct socket * to more rxrpc kernel interface functions.  They should
be starting from this rather than the socket pointer in the rxrpc_call
struct if they need to access the socket.

I have left:

	rxrpc_kernel_is_data_last()
	rxrpc_kernel_get_abort_code()
	rxrpc_kernel_get_error_number()
	rxrpc_kernel_free_skb()
	rxrpc_kernel_data_consumed()

unmodified as they're all about to be removed (and, in any case, don't
touch the socket).

Signed-off-by: David Howells <dhowells@redhat.com>
2016-08-30 16:07:53 +01:00
David Howells ea82aaec98 rxrpc: Use call->peer rather than going to the connection
Use call->peer rather than call->conn->params.peer as call->conn may become
NULL.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-08-30 16:07:53 +01:00
David Howells 8324f0bcfb rxrpc: Provide a way for AFS to ask for the peer address of a call
Provide a function so that kernel users, such as AFS, can ask for the peer
address of a call:

   void rxrpc_kernel_get_peer(struct rxrpc_call *call,
			      struct sockaddr_rxrpc *_srx);

In the future the kernel service won't get sk_buffs to look inside.
Further, this allows us to hide any canonicalisation inside AF_RXRPC for
when IPv6 support is added.

Also propagate this through to afs_find_server() and issue a warning if we
can't handle the address family yet.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-08-30 16:07:53 +01:00
David Howells e34d4234b0 rxrpc: Trace rxrpc_call usage
Add a trace event for debuging rxrpc_call struct usage.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-08-30 16:02:36 +01:00
David Howells f5c17aaeb2 rxrpc: Calls should only have one terminal state
Condense the terminal states of a call state machine to a single state,
plus a separate completion type value.  The value is then set, along with
error and abort code values, only when the call is transitioned to the
completion state.

Helpers are provided to simplify this.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-08-30 15:58:31 +01:00
David Howells ccbd3dbe85 rxrpc: Fix a potential NULL-pointer deref in rxrpc_abort_calls
The call pointer in a channel on a connection will be NULL if there's no
active call on that channel.  rxrpc_abort_calls() needs to check for this
before trying to take the call's state_lock.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-08-30 15:56:12 +01:00
David Howells 45025bceef rxrpc: Improve management and caching of client connection objects
Improve the management and caching of client rxrpc connection objects.
From this point, client connections will be managed separately from service
connections because AF_RXRPC controls the creation and re-use of client
connections but doesn't have that luxury with service connections.

Further, there will be limits on the numbers of client connections that may
be live on a machine.  No direct restriction will be placed on the number
of client calls, excepting that each client connection can support a
maximum of four concurrent calls.

Note that, for a number of reasons, we don't want to simply discard a
client connection as soon as the last call is apparently finished:

 (1) Security is negotiated per-connection and the context is then shared
     between all calls on that connection.  The context can be negotiated
     again if the connection lapses, but that involves holding up calls
     whilst at least two packets are exchanged and various crypto bits are
     performed - so we'd ideally like to cache it for a little while at
     least.

 (2) If a packet goes astray, we will need to retransmit a final ACK or
     ABORT packet.  To make this work, we need to keep around the
     connection details for a little while.

 (3) The locally held structures represent some amount of setup time, to be
     weighed against their occupation of memory when idle.


To this end, the client connection cache is managed by a state machine on
each connection.  There are five states:

 (1) INACTIVE - The connection is not held in any list and may not have
     been exposed to the world.  If it has been previously exposed, it was
     discarded from the idle list after expiring.

 (2) WAITING - The connection is waiting for the number of client conns to
     drop below the maximum capacity.  Calls may be in progress upon it
     from when it was active and got culled.

     The connection is on the rxrpc_waiting_client_conns list which is kept
     in to-be-granted order.  Culled conns with waiters go to the back of
     the queue just like new conns.

 (3) ACTIVE - The connection has at least one call in progress upon it, it
     may freely grant available channels to new calls and calls may be
     waiting on it for channels to become available.

     The connection is on the rxrpc_active_client_conns list which is kept
     in activation order for culling purposes.

 (4) CULLED - The connection got summarily culled to try and free up
     capacity.  Calls currently in progress on the connection are allowed
     to continue, but new calls will have to wait.  There can be no waiters
     in this state - the conn would have to go to the WAITING state
     instead.

 (5) IDLE - The connection has no calls in progress upon it and must have
     been exposed to the world (ie. the EXPOSED flag must be set).  When it
     expires, the EXPOSED flag is cleared and the connection transitions to
     the INACTIVE state.

     The connection is on the rxrpc_idle_client_conns list which is kept in
     order of how soon they'll expire.

A connection in the ACTIVE or CULLED state must have at least one active
call upon it; if in the WAITING state it may have active calls upon it;
other states may not have active calls.

As long as a connection remains active and doesn't get culled, it may
continue to process calls - even if there are connections on the wait
queue.  This simplifies things a bit and reduces the amount of checking we
need do.


There are a couple flags of relevance to the cache:

 (1) EXPOSED - The connection ID got exposed to the world.  If this flag is
     set, an extra ref is added to the connection preventing it from being
     reaped when it has no calls outstanding.  This flag is cleared and the
     ref dropped when a conn is discarded from the idle list.

 (2) DONT_REUSE - The connection should be discarded as soon as possible and
     should not be reused.


This commit also provides a number of new settings:

 (*) /proc/net/rxrpc/max_client_conns

     The maximum number of live client connections.  Above this number, new
     connections get added to the wait list and must wait for an active
     conn to be culled.  Culled connections can be reused, but they will go
     to the back of the wait list and have to wait.

 (*) /proc/net/rxrpc/reap_client_conns

     If the number of desired connections exceeds the maximum above, the
     active connection list will be culled until there are only this many
     left in it.

 (*) /proc/net/rxrpc/idle_conn_expiry

     The normal expiry time for a client connection, provided there are
     fewer than reap_client_conns of them around.

 (*) /proc/net/rxrpc/idle_conn_fast_expiry

     The expedited expiry time, used when there are more than
     reap_client_conns of them around.


Note that I combined the Tx wait queue with the channel grant wait queue to
save space as only one of these should be in use at once.

Note also that, for the moment, the service connection cache still uses the
old connection management code.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-08-24 15:17:14 +01:00
David Howells 4d028b2c82 rxrpc: Dup the main conn list for the proc interface
The main connection list is used for two independent purposes: primarily it
is used to find connections to reap and secondarily it is used to list
connections in procfs.

Split the procfs list out from the reap list.  This allows us to stop using
the reap list for client connections when they acquire a separate
management strategy from service collections.

The client connections will not be on a management single list, and sometimes
won't be on a management list at all.  This doesn't leave them floating,
however, as they will also be on an rb-tree rooted on the socket so that the
socket can find them to dispatch calls.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-08-24 15:17:14 +01:00
David Howells df5d8bf70f rxrpc: Make /proc/net/rxrpc_calls safer
Make /proc/net/rxrpc_calls safer by stashing a copy of the peer pointer in
the rxrpc_call struct and checking in the show routine that the peer
pointer, the socket pointer and the local pointer obtained from the socket
pointer aren't NULL before we use them.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-08-24 15:15:59 +01:00
David Howells 2266ffdef5 rxrpc: Fix conn-based retransmit
If a duplicate packet comes in for a call that has just completed on a
connection's channel then there will be an oops in the data_ready handler
because it tries to examine the connection struct via a call struct (which
we don't have - the pointer is unset).

Since the connection struct pointer is available to us, go direct instead.

Also, the ACK packet to be retransmitted needs three octets of padding
between the soft ack list and the ackinfo.

Fixes: 18bfeba50d ("rxrpc: Perform terminal call ACK/ABORT retransmission from conn processor")
Signed-off-by: David Howells <dhowells@redhat.com>
2016-08-24 13:06:14 +01:00
David Howells 18bfeba50d rxrpc: Perform terminal call ACK/ABORT retransmission from conn processor
Perform terminal call ACK/ABORT retransmission in the connection processor
rather than in the call processor.  With this change, once last_call is
set, no more incoming packets will be routed to the corresponding call or
any earlier calls on that channel (call IDs must only increase on a channel
on a connection).

Further, if a packet's callNumber is before the last_call ID or a packet is
aimed at successfully completed service call then that packet is discarded
and ignored.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-08-23 16:02:35 +01:00
David Howells 563ea7d5d4 rxrpc: Calculate serial skew on packet reception
Calculate the serial number skew in the data_ready handler when a packet
has been received and a connection looked up.  The skew is cached in the
sk_buff's priority field.

The connection highest received serial number is updated at this time also.
This can be done without locks or atomic instructions because, at this
point, the code is serialised by the socket.

This generates more accurate skew data because if the packet is offloaded
to a work queue before this is determined, more packets may come in,
bumping the highest serial number and thereby increasing the apparent skew.

This also removes some unnecessary atomic ops.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-08-23 16:02:35 +01:00
David Howells f51b448002 rxrpc: Set connection expiry on idle, not put
Set the connection expiry time when a connection becomes idle rather than
doing this in rxrpc_put_connection().  This makes the put path more
efficient (it is likely to be called occasionally whilst a connection has
outstanding calls because active workqueue items needs to be given a ref).

The time is also preset in the connection allocator in case the connection
never gets used.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-08-23 16:02:35 +01:00
David Howells df844fd46b rxrpc: Use a tracepoint for skb accounting debugging
Use a tracepoint to log various skb accounting points to help in debugging
refcounting errors.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-08-23 15:27:24 +01:00
David Howells 01a90a4598 rxrpc: Drop channel number field from rxrpc_call struct
Drop the channel number (channel) field from the rxrpc_call struct to
reduce the size of the call struct.  The field is redundant: if the call is
attached to a connection, the channel can be obtained from there by AND'ing
with RXRPC_CHANNELMASK.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-08-23 15:27:24 +01:00
David Howells f36b5e444c rxrpc: When clearing a socket, clear the call sets in the right order
When clearing a socket, we should clear the securing-in-progress list
first, then the accept queue and last the main call tree because that's the
order in which a call progresses.  Not that a call should move from the
accept queue to the main tree whilst we're shutting down a socket, but it a
call could possibly move from sequreq to acceptq whilst we're clearing up.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-08-23 15:27:24 +01:00
David Howells dabe5a7906 rxrpc: Tidy up the rxrpc_call struct a bit
Do a little tidying of the rxrpc_call struct:

 (1) in_clientflag is no longer compared against the value that's in the
     packet, so keeping it in this form isn't necessary.  Use a flag in
     flags instead and provide a pair of wrapper functions.

 (2) We don't read the epoch value, so that can go.

 (3) Move what remains of the data that were used for hashing up in the
     struct to be with the channel number.

 (4) Get rid of the local pointer.  We can get at this via the socket
     struct and we only use this in the procfs viewer.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-08-23 15:27:24 +01:00
David Howells 26164e77ca rxrpc: Remove RXRPC_CALL_PROC_BUSY
Remove RXRPC_CALL_PROC_BUSY as work queue items are now 100% non-reentrant.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-08-23 15:27:23 +01:00
David Howells 992c273af9 rxrpc: Free packets discarded in data_ready
Under certain conditions, the data_ready handler will discard a packet.
These need to be freed.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-08-09 17:13:56 +01:00
David Howells 50fd85a1f9 rxrpc: Fix a use-after-push in data_ready handler
Fix a use of a packet after it has been enqueued onto the packet processing
queue in the data_ready handler.  Once on a call's Rx queue, we mustn't
touch it any more as it may be dequeued and freed by the call processor
running on a work queue.

Save the values we need before enqueuing.

Without this, we can get an oops like the following:

BUG: unable to handle kernel NULL pointer dereference at 000000000000009c
IP: [<ffffffffa01854e8>] rxrpc_fast_process_packet+0x724/0xa11 [af_rxrpc]
PGD 0 
Oops: 0000 [#1] SMP
Modules linked in: kafs(E) af_rxrpc(E) [last unloaded: af_rxrpc]
CPU: 2 PID: 0 Comm: swapper/2 Tainted: G            E   4.7.0-fsdevel+ #1336
Hardware name: ASUS All Series/H97-PLUS, BIOS 2306 10/09/2014
task: ffff88040d6863c0 task.stack: ffff88040d68c000
RIP: 0010:[<ffffffffa01854e8>]  [<ffffffffa01854e8>] rxrpc_fast_process_packet+0x724/0xa11 [af_rxrpc]
RSP: 0018:ffff88041fb03a78  EFLAGS: 00010246
RAX: ffffffffffffffff RBX: ffff8803ff195b00 RCX: 0000000000000001
RDX: ffffffffa01854d1 RSI: 0000000000000008 RDI: ffff8803ff195b00
RBP: ffff88041fb03ab0 R08: 0000000000000000 R09: 0000000000000001
R10: ffff88041fb038c8 R11: 0000000000000000 R12: ffff880406874800
R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff88041fb00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000000009c CR3: 0000000001c14000 CR4: 00000000001406e0
Stack:
 ffff8803ff195ea0 ffff880408348800 ffff880406874800 ffff8803ff195b00
 ffff880408348800 ffff8803ff195ed8 0000000000000000 ffff88041fb03af0
 ffffffffa0186072 0000000000000000 ffff8804054da000 0000000000000000
Call Trace:
 <IRQ> 
 [<ffffffffa0186072>] rxrpc_data_ready+0x89d/0xbae [af_rxrpc]
 [<ffffffff814c94d7>] __sock_queue_rcv_skb+0x24c/0x2b2
 [<ffffffff8155c59a>] __udp_queue_rcv_skb+0x4b/0x1bd
 [<ffffffff8155e048>] udp_queue_rcv_skb+0x281/0x4db
 [<ffffffff8155ea8f>] __udp4_lib_rcv+0x7ed/0x963
 [<ffffffff8155ef9a>] udp_rcv+0x15/0x17
 [<ffffffff81531d86>] ip_local_deliver_finish+0x1c3/0x318
 [<ffffffff81532544>] ip_local_deliver+0xbb/0xc4
 [<ffffffff81531bc3>] ? inet_del_offload+0x40/0x40
 [<ffffffff815322a9>] ip_rcv_finish+0x3ce/0x42c
 [<ffffffff81532851>] ip_rcv+0x304/0x33d
 [<ffffffff81531edb>] ? ip_local_deliver_finish+0x318/0x318
 [<ffffffff814dff9d>] __netif_receive_skb_core+0x601/0x6e8
 [<ffffffff814e072e>] __netif_receive_skb+0x13/0x54
 [<ffffffff814e082a>] netif_receive_skb_internal+0xbb/0x17c
 [<ffffffff814e1838>] napi_gro_receive+0xf9/0x1bd
 [<ffffffff8144eb9f>] rtl8169_poll+0x32b/0x4a8
 [<ffffffff814e1c7b>] net_rx_action+0xe8/0x357
 [<ffffffff81051074>] __do_softirq+0x1aa/0x414
 [<ffffffff810514ab>] irq_exit+0x3d/0xb0
 [<ffffffff810184a2>] do_IRQ+0xe4/0xfc
 [<ffffffff81612053>] common_interrupt+0x93/0x93
 <EOI> 
 [<ffffffff814af837>] ? cpuidle_enter_state+0x1ad/0x2be
 [<ffffffff814af832>] ? cpuidle_enter_state+0x1a8/0x2be
 [<ffffffff814af96a>] cpuidle_enter+0x12/0x14
 [<ffffffff8108956f>] call_cpuidle+0x39/0x3b
 [<ffffffff81089855>] cpu_startup_entry+0x230/0x35d
 [<ffffffff810312ea>] start_secondary+0xf4/0xf7

Signed-off-by: David Howells <dhowells@redhat.com>
2016-08-09 17:13:55 +01:00
David Howells 2e7e9758b2 rxrpc: Once packet posted in data_ready, don't retry posting
Once a packet has been posted to a connection in the data_ready handler, we
mustn't try reposting if we then find that the connection is dying as the
refcount has been given over to the dying connection and the packet might
no longer exist.

Losing the packet isn't a problem as the peer will retransmit.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-08-09 17:13:55 +01:00
David Howells f9dc575725 rxrpc: Don't access connection from call if pointer is NULL
The call state machine processor sets up the message parameters for a UDP
message that it might need to transmit in advance on the basis that there's
a very good chance it's going to have to transmit either an ACK or an
ABORT.  This requires it to look in the connection struct to retrieve some
of the parameters.

However, if the call is complete, the call connection pointer may be NULL
to dissuade the processor from transmitting a message.  However, there are
some situations where the processor is still going to be called - and it's
still going to set up message parameters whether it needs them or not.

This results in a NULL pointer dereference at:

	net/rxrpc/call_event.c:837

To fix this, skip the message pre-initialisation if there's no connection
attached.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-08-09 17:12:23 +01:00
David Howells 17b963e319 rxrpc: Need to flag call as being released on connect failure
If rxrpc_new_client_call() fails to make a connection, the call record that
it allocated needs to be marked as RXRPC_CALL_RELEASED before it is passed
to rxrpc_put_call() to indicate that it no longer has any attachment to the
AF_RXRPC socket.

Without this, an assertion failure may occur at:

	net/rxrpc/call_object:635

Signed-off-by: David Howells <dhowells@redhat.com>
2016-08-09 17:12:23 +01:00
Arnd Bergmann 55cae7a403 rxrpc: fix uninitialized pointer dereference in debug code
A newly added bugfix caused an uninitialized variable to be
used for printing debug output. This is harmless as long
as the debug setting is disabled, but otherwise leads to an
immediate crash.

gcc warns about this when -Wmaybe-uninitialized is enabled:

net/rxrpc/call_object.c: In function 'rxrpc_release_call':
net/rxrpc/call_object.c:496:163: error: 'sp' may be used uninitialized in this function [-Werror=maybe-uninitialized]

The initialization was removed but one of the users remains.
This adds back the initialization.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: 372ee16386 ("rxrpc: Fix races between skb free, ACK generation and replying")
Signed-off-by: David Howells <dhowells@redhat.com>
2016-08-09 10:51:38 +01:00
David Howells 372ee16386 rxrpc: Fix races between skb free, ACK generation and replying
Inside the kafs filesystem it is possible to occasionally have a call
processed and terminated before we've had a chance to check whether we need
to clean up the rx queue for that call because afs_send_simple_reply() ends
the call when it is done, but this is done in a workqueue item that might
happen to run to completion before afs_deliver_to_call() completes.

Further, it is possible for rxrpc_kernel_send_data() to be called to send a
reply before the last request-phase data skb is released.  The rxrpc skb
destructor is where the ACK processing is done and the call state is
advanced upon release of the last skb.  ACK generation is also deferred to
a work item because it's possible that the skb destructor is not called in
a context where kernel_sendmsg() can be invoked.

To this end, the following changes are made:

 (1) kernel_rxrpc_data_consumed() is added.  This should be called whenever
     an skb is emptied so as to crank the ACK and call states.  This does
     not release the skb, however.  kernel_rxrpc_free_skb() must now be
     called to achieve that.  These together replace
     rxrpc_kernel_data_delivered().

 (2) kernel_rxrpc_data_consumed() is wrapped by afs_data_consumed().

     This makes afs_deliver_to_call() easier to work as the skb can simply
     be discarded unconditionally here without trying to work out what the
     return value of the ->deliver() function means.

     The ->deliver() functions can, via afs_data_complete(),
     afs_transfer_reply() and afs_extract_data() mark that an skb has been
     consumed (thereby cranking the state) without the need to
     conditionally free the skb to make sure the state is correct on an
     incoming call for when the call processor tries to send the reply.

 (3) rxrpc_recvmsg() now has to call kernel_rxrpc_data_consumed() when it
     has finished with a packet and MSG_PEEK isn't set.

 (4) rxrpc_packet_destructor() no longer calls rxrpc_hard_ACK_data().

     Because of this, we no longer need to clear the destructor and put the
     call before we free the skb in cases where we don't want the ACK/call
     state to be cranked.

 (5) The ->deliver() call-type callbacks are made to return -EAGAIN rather
     than 0 if they expect more data (afs_extract_data() returns -EAGAIN to
     the delivery function already), and the caller is now responsible for
     producing an abort if that was the last packet.

 (6) There are many bits of unmarshalling code where:

 		ret = afs_extract_data(call, skb, last, ...);
		switch (ret) {
		case 0:		break;
		case -EAGAIN:	return 0;
		default:	return ret;
		}

     is to be found.  As -EAGAIN can now be passed back to the caller, we
     now just return if ret < 0:

 		ret = afs_extract_data(call, skb, last, ...);
		if (ret < 0)
			return ret;

 (7) Checks for trailing data and empty final data packets has been
     consolidated as afs_data_complete().  So:

		if (skb->len > 0)
			return -EBADMSG;
		if (!last)
			return 0;

     becomes:

		ret = afs_data_complete(call, skb, last);
		if (ret < 0)
			return ret;

 (8) afs_transfer_reply() now checks the amount of data it has against the
     amount of data desired and the amount of data in the skb and returns
     an error to induce an abort if we don't get exactly what we want.

Without these changes, the following oops can occasionally be observed,
particularly if some printks are inserted into the delivery path:

general protection fault: 0000 [#1] SMP
Modules linked in: kafs(E) af_rxrpc(E) [last unloaded: af_rxrpc]
CPU: 0 PID: 1305 Comm: kworker/u8:3 Tainted: G            E   4.7.0-fsdevel+ #1303
Hardware name: ASUS All Series/H97-PLUS, BIOS 2306 10/09/2014
Workqueue: kafsd afs_async_workfn [kafs]
task: ffff88040be041c0 ti: ffff88040c070000 task.ti: ffff88040c070000
RIP: 0010:[<ffffffff8108fd3c>]  [<ffffffff8108fd3c>] __lock_acquire+0xcf/0x15a1
RSP: 0018:ffff88040c073bc0  EFLAGS: 00010002
RAX: 6b6b6b6b6b6b6b6b RBX: 0000000000000000 RCX: ffff88040d29a710
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88040d29a710
RBP: ffff88040c073c70 R08: 0000000000000001 R09: 0000000000000001
R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: ffff88040be041c0 R15: ffffffff814c928f
FS:  0000000000000000(0000) GS:ffff88041fa00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa4595f4750 CR3: 0000000001c14000 CR4: 00000000001406f0
Stack:
 0000000000000006 000000000be04930 0000000000000000 ffff880400000000
 ffff880400000000 ffffffff8108f847 ffff88040be041c0 ffffffff81050446
 ffff8803fc08a920 ffff8803fc08a958 ffff88040be041c0 ffff88040c073c38
Call Trace:
 [<ffffffff8108f847>] ? mark_held_locks+0x5e/0x74
 [<ffffffff81050446>] ? __local_bh_enable_ip+0x9b/0xa1
 [<ffffffff8108f9ca>] ? trace_hardirqs_on_caller+0x16d/0x189
 [<ffffffff810915f4>] lock_acquire+0x122/0x1b6
 [<ffffffff810915f4>] ? lock_acquire+0x122/0x1b6
 [<ffffffff814c928f>] ? skb_dequeue+0x18/0x61
 [<ffffffff81609dbf>] _raw_spin_lock_irqsave+0x35/0x49
 [<ffffffff814c928f>] ? skb_dequeue+0x18/0x61
 [<ffffffff814c928f>] skb_dequeue+0x18/0x61
 [<ffffffffa009aa92>] afs_deliver_to_call+0x344/0x39d [kafs]
 [<ffffffffa009ab37>] afs_process_async_call+0x4c/0xd5 [kafs]
 [<ffffffffa0099e9c>] afs_async_workfn+0xe/0x10 [kafs]
 [<ffffffff81063a3a>] process_one_work+0x29d/0x57c
 [<ffffffff81064ac2>] worker_thread+0x24a/0x385
 [<ffffffff81064878>] ? rescuer_thread+0x2d0/0x2d0
 [<ffffffff810696f5>] kthread+0xf3/0xfb
 [<ffffffff8160a6ff>] ret_from_fork+0x1f/0x40
 [<ffffffff81069602>] ? kthread_create_on_node+0x1cf/0x1cf

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-08-06 00:08:40 -04:00
Dan Carpenter 7acef60455 rxrpc: checking for IS_ERR() instead of NULL
The rxrpc_lookup_peer() function returns NULL on error, it never returns
error pointers.

Fixes: 8496af50eb ('rxrpc: Use RCU to access a peer's service connection tree')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-07-15 14:16:25 -07:00
Wei Yongjun 8addc0440b rxrpc: Fix error handling in af_rxrpc_init()
security initialized after alloc workqueue, so we should exit security
before destroy workqueue in the error handing.

Fixes: 648af7fca1 ("rxrpc: Absorb the rxkad security module")
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-07-12 11:07:38 -07:00
David Howells d440a1ce5d rxrpc: Kill off the call hash table
The call hash table is now no longer used as calls are looked up directly
by channel slot on the connection, so kill it off.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-07-06 11:23:54 +01:00
David Howells 8496af50eb rxrpc: Use RCU to access a peer's service connection tree
Move to using RCU access to a peer's service connection tree when routing
an incoming packet.  This is done using a seqlock to trigger retrying of
the tree walk if a change happened.

Further, we no longer get a ref on the connection looked up in the
data_ready handler unless we queue the connection's work item - and then
only if the refcount > 0.


Note that I'm avoiding the use of a hash table for service connections
because each service connection is addressed by a 62-bit number
(constructed from epoch and connection ID >> 2) that would allow the client
to engage in bucket stuffing, given knowledge of the hash algorithm.
Peers, however, are hashed as the network address is less controllable by
the client.  The total number of peers will also be limited in a future
commit.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-07-06 10:51:14 +01:00
David Howells 1291e9d108 rxrpc: Move data_ready peer lookup into rxrpc_find_connection()
Move the peer lookup done in input.c by data_ready into
rxrpc_find_connection().

Signed-off-by: David Howells <dhowells@redhat.com>
2016-07-06 10:51:14 +01:00
David Howells e8d70ce177 rxrpc: Prune the contents of the rxrpc_conn_proto struct
Prune the contents of the rxrpc_conn_proto struct.  Most of the fields aren't
used anymore.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-07-06 10:51:14 +01:00
David Howells 001c112249 rxrpc: Maintain an extra ref on a conn for the cache list
Overhaul the usage count accounting for the rxrpc_connection struct to make
it easier to implement RCU access from the data_ready handler.

The problem is that currently we're using a lock to prevent the garbage
collector from trying to clean up a connection that we're contemplating
unidling.  We could just stick incoming packets on the connection we find,
but we've then got a problem that we may race when dispatching a work item
to process it as we need to give that a ref to prevent the rxrpc_connection
struct from disappearing in the meantime.

Further, incoming packets may get discarded if attached to an
rxrpc_connection struct that is going away.  Whilst this is not a total
disaster - the client will presumably resend - it would delay processing of
the call.  This would affect the AFS client filesystem's service manager
operation.

To this end:

 (1) We now maintain an extra count on the connection usage count whilst it
     is on the connection list.  This mean it is not in use when its
     refcount is 1.

 (2) When trying to reuse an old connection, we only increment the refcount
     if it is greater than 0.  If it is 0, we replace it in the tree with a
     new candidate connection.

 (3) Two connection flags are added to indicate whether or not a connection
     is in the local's client connection tree (used by sendmsg) or the
     peer's service connection tree (used by data_ready).  This makes sure
     that we don't try and remove a connection if it got replaced.

     The flags are tested under lock with the removal operation to prevent
     the reaper from killing the rxrpc_connection struct whilst someone
     else is trying to effect a replacement.

     This could probably be alleviated by using memory barriers between the
     flag set/test and the rb_tree ops.  The rb_tree op would still need to
     be under the lock, however.

 (4) When trying to reap an old connection, we try to flip the usage count
     from 1 to 0.  If it's not 1 at that point, then it must've come back
     to life temporarily and we ignore it.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-07-06 10:50:04 +01:00
David Howells d991b4a32f rxrpc: Move peer lookup from call-accept to new-incoming-conn
Move the lookup of a peer from a call that's being accepted into the
function that creates a new incoming connection.  This will allow us to
avoid incrementing the peer's usage count in some cases in future.

Note that I haven't bother to integrate rxrpc_get_addr_from_skb() with
rxrpc_extract_addr_from_skb() as I'm going to delete the former in the very
near future.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-07-06 10:49:57 +01:00
David Howells 7877a4a4bd rxrpc: Split service connection code out into its own file
Split the service-specific connection code out into into its own file.  The
client-specific code has already been split out.  This will leave just the
common code in the original file.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-07-06 10:49:35 +01:00
David Howells c6d2b8d764 rxrpc: Split client connection code out into its own file
Split the client-specific connection code out into its own file.  It will
behave somewhat differently from the service-specific connection code, so
it makes sense to separate them.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-07-06 10:43:52 +01:00
David Howells a1399f8bb0 rxrpc: Call channels should have separate call number spaces
Each channel on a connection has a separate, independent number space from
which to allocate callNumber values.  It is entirely possible, for example,
to have a connection with four active calls, each with call number 1.

Note that the callNumber values for any particular channel don't have to
start at 1, but they are supposed to increment monotonically for that
channel from a client's perspective and may not be reused once the call
number is transmitted (until the epoch cycles all the way back round).

Currently, however, call numbers are allocated on a per-connection basis
and, further, are held in an rb-tree.  The rb-tree is redundant as the four
channel pointers in the rxrpc_connection struct are entirely capable of
pointing to all the calls currently in progress on a connection.

To this end, make the following changes:

 (1) Handle call number allocation independently per channel.

 (2) Get rid of the conn->calls rb-tree.  This is overkill as a connection
     may have a maximum of four calls in progress at any one time.  Use the
     pointers in the channels[] array instead, indexed by the channel
     number from the packet.

 (3) For each channel, save the result of the last call that was in
     progress on that channel in conn->channels[] so that the final ACK or
     ABORT packet can be replayed if necessary.  Any call earlier than that
     is just ignored.  If we've seen the next call number in a packet, the
     last one is most definitely defunct.

 (4) When generating a RESPONSE packet for a connection, the call number
     counter for each channel must be included in it.

 (5) When parsing a RESPONSE packet for a connection, the call number
     counters contained therein should be used to set the minimum expected
     call numbers on each channel.

To do in future commits:

 (1) Replay terminal packets based on the last call stored in
     conn->channels[].

 (2) Connections should be retired before the callNumber space on any
     channel runs out.

 (3) A server is expected to disregard or reject any new incoming call that
     has a call number less than the current call number counter.  The call
     number counter for that channel must be advanced to the new call
     number.

     Note that the server cannot just require that the next call that it
     sees on a channel be exactly the call number counter + 1 because then
     there's a scenario that could cause a problem: The client transmits a
     packet to initiate a connection, the network goes out, the server
     sends an ACK (which gets lost), the client sends an ABORT (which also
     gets lost); the network then reconnects, the client then reuses the
     call number for the next call (it doesn't know the server already saw
     the call number), but the server thinks it already has the first
     packet of this call (it doesn't know that the client doesn't know that
     it saw the call number the first time).

Signed-off-by: David Howells <dhowells@redhat.com>
2016-07-06 10:43:52 +01:00
David Howells 30b515f4d1 rxrpc: Access socket accept queue under right lock
The socket's accept queue (socket->acceptq) should be accessed under
socket->call_lock, not under the connection lock.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-07-06 10:43:51 +01:00
David Howells dee46364ce rxrpc: Add RCU destruction for connections and calls
Add RCU destruction for connections and calls as the RCU lookup from the
transport socket data_ready handler is going to come along shortly.

Whilst we're at it, move the cleanup workqueue flushing and RCU barrierage
into the destruction code for the objects that need it (locals and
connections) and add the extra RCU barrier required for connection cleanup.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-07-06 10:43:51 +01:00
David Howells e653cfe49c rxrpc: Release a call's connection ref on call disconnection
When a call is disconnected, clear the call's pointer to the connection and
release the associated ref on that connection.  This means that the call no
longer pins the connection and the connection can be discarded even before
the call is.

As the code currently stands, the call struct is effectively pinned by
userspace until userspace has enacted a recvmsg() to retrieve the final
call state as sk_buffs on the receive queue pin the call to which they're
related because:

 (1) The rxrpc_call struct contains the userspace ID that recvmsg() has to
     include in the control message buffer to indicate which call is being
     referred to.  This ID must remain valid until the terminal packet is
     completely read and must be invalidated immediately at that point as
     userspace is entitled to immediately reuse it.

 (2) The final ACK to the reply to a client call isn't sent until the last
     data packet is entirely read (it's probably worth altering this in
     future to be send the ACK as soon as all the data has been received).


This change requires a bit of rearrangement to make sure that the call
isn't going to try and access the connection again after protocol
completion:

 (1) Delete the error link earlier when we're releasing the call.  Possibly
     network errors should be distributed via connections at the cost of
     adding in an access to the rxrpc_connection struct.

 (2) Remove the call from the connection's call tree before disconnecting
     the call.  The call tree needs to be removed anyway and incoming
     packets delivered by channel pointer instead.

 (3) The release call event should be considered last after all other
     events have been processed so that we don't need access to the
     connection again.

 (4) Move the channel_lock taking from rxrpc_release_call() to
     rxrpc_disconnect_call() where it will be required in future.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-07-06 10:43:51 +01:00
David Howells d1e858c5a3 rxrpc: Fix handling of connection failure in client call creation
If rxrpc_connect_call() fails during the creation of a client connection,
there are two bugs that we can hit that need fixing:

 (1) The call state should be moved to RXRPC_CALL_DEAD before the call
     cleanup phase is invoked.  If not, this can cause an assertion failure
     later.

 (2) call->link should be reinitialised after being deleted in
     rxrpc_new_client_call() - which otherwise leads to a failure later
     when the call cleanup attempts to delete the link again.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-07-06 10:43:51 +01:00
David Howells 2c4579e4b1 rxrpc: Move usage count getting into rxrpc_queue_conn()
Rather than calling rxrpc_get_connection() manually before calling
rxrpc_queue_conn(), do it inside the queue wrapper.

This allows us to do some important fixes:

 (1) If the usage count is 0, do nothing.  This prevents connections from
     being reanimated once they're dead.

 (2) If rxrpc_queue_work() fails because the work item is already queued,
     retract the usage count increment which would otherwise be lost.

 (3) Don't take a ref on the connection in the work function.  By passing
     the ref through the work item, this is unnecessary.  Doing it in the
     work function is too late anyway.  Previously, connection-directed
     packets held a ref on the connection, but that's not really the best
     idea.

And another useful changes:

 (*) Don't need to take a refcount on the connection in the data_ready
     handler unless we invoke the connection's work item.  We're using RCU
     there so that's otherwise redundant.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-07-06 10:43:51 +01:00
David Howells eb9b9d2275 rxrpc: Check that the client conns cache is empty before module removal
Check that the client conns cache is empty before module removal and bug if
not, listing any offending connections that are still present.  Unfortunately,
if there are connections still around, then the transport socket is still
unexpectedly open and active, so we can't just unallocate the connections.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-07-06 10:43:51 +01:00
David Howells bba304db34 rxrpc: Turn connection #defines into enums and put outside struct def
Turn the connection event and state #define lists into enums and move
outside of the struct definition.

Whilst we're at it, change _SERVER to _SERVICE in those identifiers and add
EV_ into the event name to distinguish them from flags and states.

Also add a symbol indicating the number of states and use that in the state
text array.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-07-06 10:43:51 +01:00
David Howells 5acbee4648 rxrpc: Provide queuing helper functions
Provide queueing helper functions so that the queueing of local and
connection objects can be fixed later.

The issue is that a ref on the object needs to be passed to the work queue,
but the act of queueing the object may fail because the object is already
queued.  Testing the queuedness of an object before hand doesn't work
because there can be a race with someone else trying to queue it.  What
will have to be done is to adjust the refcount depending on the result of
the queue operation.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-07-06 10:43:05 +01:00