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We need to generate a DELAY ACK from the service end of an operation if we
start doing the actual operation work and it takes longer than expected.
This will hard-ACK the request data and allow the client to release its
resources.
To make this work:
(1) We have to set the ack timer and propose an ACK when the call moves to
the RXRPC_CALL_SERVER_ACK_REQUEST and clear the pending ACK and cancel
the timer when we start transmitting the reply (the first DATA packet
of the reply implicitly ACKs the request phase).
(2) It must be possible to set the timer when the caller is holding
call->state_lock, so split the lock-getting part of the timer function
out.
(3) Add trace notes for the ACK we're requesting and the timer we clear.
Signed-off-by: David Howells <dhowells@redhat.com>
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The call's background processor work item needs to notify the socket when
it completes a call so that recvmsg() or the AFS fs can deal with it.
Without this, call expiry isn't handled.
Signed-off-by: David Howells <dhowells@redhat.com>
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When a call expires, it must be queued for the background processor to deal
with otherwise a service call that is improperly terminated will just sit
there awaiting an ACK and won't expire.
Signed-off-by: David Howells <dhowells@redhat.com>
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Separate the output of PING ACKs from the output of other sorts of ACK so
that if we receive a PING ACK and schedule transmission of a PING RESPONSE
ACK, the response doesn't get cancelled by a PING ACK we happen to be
scheduling transmission of at the same time.
If a PING RESPONSE gets lost, the other side might just sit there waiting
for it and refuse to proceed otherwise.
Signed-off-by: David Howells <dhowells@redhat.com>
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Split rxrpc_send_data_packet() to separate ACK generation (which is more
complicated) from ABORT generation. This simplifies the code a bit and
fixes the following warning:
In file included from ../net/rxrpc/output.c:20:0:
net/rxrpc/output.c: In function 'rxrpc_send_call_packet':
net/rxrpc/ar-internal.h:1187:27: error: 'top' may be used uninitialized in this function [-Werror=maybe-uninitialized]
net/rxrpc/output.c:103:24: note: 'top' was declared here
net/rxrpc/output.c:225:25: error: 'hard_ack' may be used uninitialized in this function [-Werror=maybe-uninitialized]
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David Howells <dhowells@redhat.com>
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The call timer's concept of a call timeout (of which there are three) that
is inactive is that it is the timeout has the same expiration time as the
call expiration timeout (the expiration timer is never inactive). However,
I'm not resetting the timeouts when they expire, leading to repeated
processing of expired timeouts when other timeout events occur.
Fix this by:
(1) Move the timer expiry detection into rxrpc_set_timer() inside the
locked section. This means that if a timeout is set that will expire
immediately, we deal with it immediately.
(2) If a timeout is at or before now then it has expired. When an expiry
is detected, an event is raised, the timeout is automatically
inactivated and the event processor is queued.
(3) If a timeout is at or after the expiry timeout then it is inactive.
Inactive timeouts do not contribute to the timer setting.
(4) The call timer callback can now just call rxrpc_set_timer() to handle
things.
(5) The call processor work function now checks the event flags rather
than checking the timeouts directly.
Signed-off-by: David Howells <dhowells@redhat.com>
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Keep that call timeouts as ktimes rather than jiffies so that they can be
expressed as functions of RTT.
Signed-off-by: David Howells <dhowells@redhat.com>
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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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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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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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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>
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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>
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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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Add a tracepoint to log call timer initiation, setting and expiry.
Signed-off-by: David Howells <dhowells@redhat.com>
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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>
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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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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>
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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>
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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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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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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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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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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>
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Remove a tab that's on a line that should otherwise be blank.
Signed-off-by: David Howells <dhowells@redhat.com>
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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>
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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>
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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>
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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>
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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>
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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>
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Use call->peer rather than call->conn->params.peer as call->conn may become
NULL.
Signed-off-by: David Howells <dhowells@redhat.com>
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Add a trace event for debuging rxrpc_call struct usage.
Signed-off-by: David Howells <dhowells@redhat.com>
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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>
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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>
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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>
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Use a tracepoint to log various skb accounting points to help in debugging
refcounting errors.
Signed-off-by: David Howells <dhowells@redhat.com>
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Remove RXRPC_CALL_PROC_BUSY as work queue items are now 100% non-reentrant.
Signed-off-by: David Howells <dhowells@redhat.com>
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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>
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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>
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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>
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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>
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Make rxrpc_send_packet() take a connection not a transport as part of the
phasing out of the rxrpc_transport struct.
Whilst we're at it, rename the function to rxrpc_send_data_packet() to
differentiate it from the other packet sending functions.
Signed-off-by: David Howells <dhowells@redhat.com>
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Replace accesses of conn->trans->{local,peer} with
conn->params.{local,peer} thus making it easier for a future commit to
remove the rxrpc_transport struct.
This also reduces the number of memory accesses involved.
Signed-off-by: David Howells <dhowells@redhat.com>
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Define and use a structure to hold connection parameters. This makes it
easier to pass multiple connection parameters around.
Define and use a structure to hold protocol information used to hash a
connection for lookup on incoming packet. Most of these fields will be
disposed of eventually, including the duplicate local pointer.
Whilst we're at it rename "proto" to "family" when referring to a protocol
family.
Signed-off-by: David Howells <dhowells@redhat.com>
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Use the peer record to distribute network errors rather than the transport
object (which I want to get rid of). An error from a particular peer
terminates all calls on that peer.
For future consideration:
(1) For ICMP-induced errors it might be worth trying to extract the RxRPC
header from the offending packet, if one is returned attached to the
ICMP packet, to better direct the error.
This may be overkill, though, since an ICMP packet would be expected
to be relating to the destination port, machine or network. RxRPC
ABORT and BUSY packets give notice at RxRPC level.
(2) To also abort connection-level communications (such as CHALLENGE
packets) where indicted by an error - but that requires some revamping
of the connection event handling first.
Signed-off-by: David Howells <dhowells@redhat.com>
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Rename files matching net/rxrpc/ar-*.c to get rid of the "ar-" prefix.
This will aid splitting those files by making easier to come up with new
names.
Note that the not all files are simply renamed from ar-X.c to X.c. The
following exceptions are made:
(*) ar-call.c -> call_object.c
ar-ack.c -> call_event.c
call_object.c is going to contain the core of the call object
handling. Call event handling is all going to be in call_event.c.
(*) ar-accept.c -> call_accept.c
Incoming call handling is going to be here.
(*) ar-connection.c -> conn_object.c
ar-connevent.c -> conn_event.c
The former file is going to have the basic connection object handling,
but there will likely be some differentiation between client
connections and service connections in additional files later. The
latter file will have all the connection-level event handling.
(*) ar-local.c -> local_object.c
This will have the local endpoint object handling code. The local
endpoint event handling code will later be split out into
local_event.c.
(*) ar-peer.c -> peer_object.c
This will have the peer endpoint object handling code. Peer event
handling code will be placed in peer_event.c (for the moment, there is
none).
(*) ar-error.c -> peer_event.c
This will become the peer event handling code, though for the moment
it's actually driven from the local endpoint's perspective.
Note that I haven't renamed ar-transport.c to transport_object.c as the
intention is to delete it when the rxrpc_transport struct is excised.
The only file that actually has its contents changed is net/rxrpc/Makefile.
net/rxrpc/ar-internal.h will need its section marker comments updating, but
I'll do that in a separate patch to make it easier for git to follow the
history across the rename. I may also want to rename ar-internal.h at some
point - but that would mean updating all the #includes and I'd rather do
that in a separate step.
Signed-off-by: David Howells <dhowells@redhat.com.
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