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 R

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>

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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 make

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>

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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 t

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>

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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-of

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>

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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.

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>

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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

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>

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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

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>

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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>

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. Unfortu

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>

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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 bei

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>

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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>

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

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>

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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

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>

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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

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>

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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 determini

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>

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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-retran

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>

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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(

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>

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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 ra

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>

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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>

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.co

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>

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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 bu

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>

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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 stat

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>

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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 intege

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>

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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 <dhowe

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>

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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 permi

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>

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