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: NDavid Howells <dhowells@redhat.com>

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: NDavid Howells <dhowells@redhat.com>

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: NDavid Howells <dhowells@redhat.com>

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: NDavid Howells <dhowells@redhat.com>

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: NDavid Howells <dhowells@redhat.com>

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: NDavid Howells <dhowells@redhat.com>

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: NDavid Howells <dhowells@redhat.com>

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: NDavid Howells <dhowells@redhat.com>

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: NDavid Howells <dhowells@redhat.com>

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: NDavid Howells <dhowells@redhat.com>

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: NDavid Howells <dhowells@redhat.com>

Check the return value of rxrpc_locate_data() in rxrpc_recvmsg_data().
Signed-off-by: NDavid Howells <dhowells@redhat.com>

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: NDavid Howells <dhowells@redhat.com>

Remove a tab that's on a line that should otherwise be blank.
Signed-off-by: NDavid Howells <dhowells@redhat.com>

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: Nkbuild test robot <fengguang.wu@intel.com>
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

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: NDavid Howells <dhowells@redhat.com>

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: NDavid Howells <dhowells@redhat.com>

Pass 0 as the protocol argument when creating the transport socket rather
than IPPROTO_UDP.
Signed-off-by: NDavid Howells <dhowells@redhat.com>

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: NDavid Howells <dhowells@redhat.com>

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: NDavid Howells <dhowells@redhat.com>

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: NDavid Howells <dhowells@redhat.com>

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: NDavid Howells <dhowells@redhat.com>

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: NDavid Howells <dhowells@redhat.com>

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: NDavid Howells <dhowells@redhat.com>

Add a missing unlock in rxrpc_call_accept() in the path taken if there's no
call to wake up.
Signed-off-by: NDavid Howells <dhowells@redhat.com>

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: NDavid Howells <dhowells@redhat.com>

The IDLE ACK packet should use the rxrpc_idle_ack_delay setting when the
timer is set for it.
Signed-off-by: NDavid Howells <dhowells@redhat.com>

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: NDavid Howells <dhowells@redhat.com>

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: NDavid Howells <dhowells@redhat.com>

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: NDavid Howells <dhowells@redhat.com>

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: NDavid Howells <dhowells@redhat.com>

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: NDavid Howells <dhowells@redhat.com>

Remove the sk_buff count from the rxrpc_call struct as it's less useful
once we stop queueing sk_buffs.
Signed-off-by: NDavid Howells <dhowells@redhat.com>

Convert the rxrpc_local::services list to an hlist so that it can be
accessed under RCU conditions more readily.
Signed-off-by: NDavid Howells <dhowells@redhat.com>

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: NDavid Howells <dhowells@redhat.com>

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: NDavid Howells <dhowells@redhat.com>

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: NDavid Howells <dhowells@redhat.com>

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: NDavid Howells <dhowells@redhat.com>

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: NDavid Howells <dhowells@redhat.com>

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: NDavid Howells <dhowells@redhat.com>