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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
Remove _enter/_debug/_leave calls from rxrpc_recvmsg_data() of which one
uses an uninitialised variable.
Signed-off-by: David Howells <dhowells@redhat.com>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
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>
rxkad uses stack memory in SG lists which would not work if stacks were
allocated from vmalloc memory. In fact, in most cases this isn't even
necessary as the stack memory ends up getting copied over to kmalloc
memory.
This patch eliminates all the unnecessary stack memory uses by supplying
the final destination directly to the crypto API. In two instances where a
temporary buffer is actually needed we also switch use a scratch area in
the rxrpc_call struct (only one DATA packet will be being secured or
verified at a time).
Finally there is no need to split a split-page buffer into two SG entries
so code dealing with that has been removed.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: David Howells <dhowells@redhat.com>
When looking up a client connection to which to route a packet, we need to
check that the packet came from the correct source so that a peer can't try
to muck around with another peer's connection.
Signed-off-by: David Howells <dhowells@redhat.com>
When a jumbo packet is being split up and processed, the crypto checksum
for each split-out packet is in the jumbo header and needs placing in the
reconstructed packet header.
When the code was changed to keep the stored copy of the packet header in
host byte order, this reconstruction was missed.
Found with sparse with CF=-D__CHECK_ENDIAN__:
../net/rxrpc/input.c:479:33: warning: incorrect type in assignment (different base types)
../net/rxrpc/input.c:479:33: expected unsigned short [unsigned] [usertype] _rsvd
../net/rxrpc/input.c:479:33: got restricted __be16 [addressable] [usertype] _rsvd
Fixes: 0d12f8a402 ("rxrpc: Keep the skb private record of the Rx header in host byte order")
Signed-off-by: David Howells <dhowells@redhat.com>
The rxrpc_transport struct is now redundant, given that the rxrpc_peer
struct is now per peer port rather than per peer host, so get rid of it.
Service connection lists are transferred to the rxrpc_peer struct, as is
the conn_lock. Previous patches moved the client connection handling out
of the rxrpc_transport struct and discarded the connection bundling code.
Signed-off-by: David Howells <dhowells@redhat.com>
Kill off the concept of maintaining a bundle of connections to a particular
target service to increase the number of call slots available for any
beyond four for that service (there are four call slots per connection).
This will make cleaning up the connection handling code easier and
facilitate removal of the rxrpc_transport struct. Bundling can be
reintroduced later if necessary.
Signed-off-by: David Howells <dhowells@redhat.com>
Provide refcount helper functions for connections so that the code doesn't
touch local or connection usage counts directly.
Also make it such that local and peer put functions can take a NULL
pointer.
Signed-off-by: David Howells <dhowells@redhat.com>
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>
Allocated rxrpc calls displayed in /proc/net/rxrpc_calls may in future be
on the proc list before they're connected or after they've been
disconnected - in which case they may not have a pointer to a connection
struct that can be used to get data from there.
Deal with this by using stuff from the call struct in preference where
possible and printing "no_connection" rather than a peer address if no
connection is assigned.
This change also has the added bonus that the service ID is now taken from
the call rather the connection which will allow per-call service upgrades
to be shown - something required for AuriStor server compatibility.
Signed-off-by: David Howells <dhowells@redhat.com>
Validate the net address given to rxrpc_kernel_begin_call() before using
it.
Whilst this should be mostly unnecessary for in-kernel users, it does clear
the tail of the address struct in case we want to hash or compare the whole
thing.
Signed-off-by: David Howells <dhowells@redhat.com>
Use the IDR facility to allocate client connection IDs on a machine-wide
basis so that each client connection has a unique identifier. When the
connection ID space wraps, we advance the epoch by 1, thereby effectively
having a 62-bit ID space. The IDR facility is then used to look up client
connections during incoming packet routing instead of using an rbtree
rooted on the transport.
This change allows for the removal of the transport in the future and also
means that client connections can be looked up directly in the data-ready
handler by connection ID.
The ID management code is placed in a new file, conn-client.c, to which all
the client connection-specific code will eventually move.
Note that the IDR tree gets very expensive on memory if the connection IDs
are widely scattered throughout the number space, so we shall need to
retire connections that have, say, an ID more than four times the maximum
number of client conns away from the current allocation point to try and
keep the IDs concentrated. We will also need to retire connections from an
old epoch.
Also note that, for the moment, a pointer to the transport has to be passed
through into the ID allocation function so that we can take a BH lock to
prevent a locking issue against in-BH lookup of client connections. This
will go away later when RCU is used for server connections also.
Signed-off-by: David Howells <dhowells@redhat.com>
rxrpc_connection_lock shouldn't be accessed as a BH-excluding lock. It's
only accessed in a few places and none of those are in BH-context.
rxrpc_transport::conn_lock, however, *is* a BH-excluding lock and should be
accessed so consistently.
Signed-off-by: David Howells <dhowells@redhat.com>
Pass a pointer to struct sk_buff rather than struct rxrpc_host_header to
functions so that they can in the future get at transport protocol parameters
rather than just RxRPC parameters.
Signed-off-by: David Howells <dhowells@redhat.com>
"Exclusive connections" are meant to be used for a single client call and
then scrapped. The idea is to limit the use of the negotiated security
context. The current code, however, isn't doing this: it is instead
restricting the socket to a single virtual connection and doing all the
calls over that.
This is changed such that the socket no longer maintains a special virtual
connection over which it will do all the calls, but rather gets a new one
each time a new exclusive call is made.
Further, using a socket option for this is a poor choice. It should be
done on sendmsg with a control message marker instead so that calls can be
marked exclusive individually. To that end, add RXRPC_EXCLUSIVE_CALL
which, if passed to sendmsg() as a control message element, will cause the
call to be done on an single-use connection.
The socket option (RXRPC_EXCLUSIVE_CONNECTION) still exists and, if set,
will override any lack of RXRPC_EXCLUSIVE_CALL being specified so that
programs using the setsockopt() will appear to work the same.
Signed-off-by: David Howells <dhowells@redhat.com>
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>
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>
Hashing the peer key was introduced for AF_INET, but gcc
warns about the rxrpc_peer_hash_key function returning uninitialized
data for any other value of srx->transport.family:
net/rxrpc/peer_object.c: In function 'rxrpc_peer_hash_key':
net/rxrpc/peer_object.c:57:15: error: 'p' may be used uninitialized in this function [-Werror=maybe-uninitialized]
Assuming that nothing else can be set here, this changes the
function to just return zero in case of an unknown address
family.
Fixes: be6e6707f6 ("rxrpc: Rework peer object handling to use hash table and RCU")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David Howells <dhowells@redhat.com>
rxrpc_lookup_peer_rcu() and rxrpc_lookup_peer() return NULL on error, never
error pointers, so IS_ERR() can't be used.
Fix three callers of those functions.
Fixes: be6e6707f6 ('rxrpc: Rework peer object handling to use hash table and RCU')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Rework the local RxRPC endpoint management.
Local endpoint objects are maintained in a flat list as before. This
should be okay as there shouldn't be more than one per open AF_RXRPC socket
(there can be fewer as local endpoints can be shared if their local service
ID is 0 and they share the same local transport parameters).
Changes:
(1) Local endpoints may now only be shared if they have local service ID 0
(ie. they're not being used for listening).
This prevents a scenario where process A is listening of the Cache
Manager port and process B contacts a fileserver - which may then
attempt to send CM requests back to B. But if A and B are sharing a
local endpoint, A will get the CM requests meant for B.
(2) We use a mutex to handle lookups and don't provide RCU-only lookups
since we only expect to access the list when opening a socket or
destroying an endpoint.
The local endpoint object is pointed to by the transport socket's
sk_user_data for the life of the transport socket - allowing us to
refer to it directly from the sk_data_ready and sk_error_report
callbacks.
(3) atomic_inc_not_zero() now exists and can be used to only share a local
endpoint if the last reference hasn't yet gone.
(4) We can remove rxrpc_local_lock - a spinlock that had to be taken with
BH processing disabled given that we assume sk_user_data won't change
under us.
(5) The transport socket is shut down before we clear the sk_user_data
pointer so that we can be sure that the transport socket's callbacks
won't be invoked once the RCU destruction is scheduled.
(6) Local endpoints have a work item that handles both destruction and
event processing. The means that destruction doesn't then need to
wait for event processing. The event queues can then be cleared after
the transport socket is shut down.
(7) Local endpoints are no longer available for resurrection beyond the
life of the sockets that had them open. As soon as their last ref
goes, they are scheduled for destruction and may not have their usage
count moved from 0.
Signed-off-by: David Howells <dhowells@redhat.com>
Separate local endpoint event handling out into its own file preparatory to
overhauling the object management aspect (which remains in the original
file).
Signed-off-by: David Howells <dhowells@redhat.com>
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>
Don't assume anything about the address in an ICMP packet in
rxrpc_error_report() as the address may not be IPv4 in future, especially
since we're just printing these details.
Signed-off-by: David Howells <dhowells@redhat.com>
Break MTU determination from ICMP out into its own function to reduce the
complexity of the error report handler.
Signed-off-by: David Howells <dhowells@redhat.com>
Rename rxrpc_UDP_error_report() to rxrpc_error_report() as it might get
called for something other than UDP.
Signed-off-by: David Howells <dhowells@redhat.com>
Rework peer object handling to use a hash table instead of a flat list and
to use RCU. Peer objects are no longer destroyed by passing them to a
workqueue to process, but rather are just passed to the RCU garbage
collector as kfree'able objects.
The hash function uses the local endpoint plus all the components of the
remote address, except for the RxRPC service ID. Peers thus represent a
UDP port on the remote machine as contacted by a UDP port on this machine.
The RCU read lock is used to handle non-creating lookups so that they can
be called from bottom half context in the sk_error_report handler without
having to lock the hash table against modification.
rxrpc_lookup_peer_rcu() *does* take a reference on the peer object as in
the future, this will be passed to a work item for error distribution in
the error_report path and this function will cease being used in the
data_ready path.
Creating lookups are done under spinlock rather than mutex as they might be
set up due to an external stimulus if the local endpoint is a server.
Captured network error messages (ICMP) are handled with respect to this
struct and MTU size and RTT are cached here.
Signed-off-by: David Howells <dhowells@redhat.com>
Update the section comments in ar-internal.h that indicate the locations of
the referenced items to reflect the renames done to the .c files in
net/rxrpc/.
This also involves some rearrangement to reflect keep the sections in order
of filename.
Signed-off-by: David Howells <dhowells@redhat.com>
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.
Limit the socket incoming call backlog queue size so that a remote client
can't pump in sufficient new calls that the server runs out of memory. Note
that this is partially theoretical at the moment since whilst the number of
calls is limited, the number of packets trying to set up new calls is not.
This will be addressed in a later patch.
If the caller of listen() specifies a backlog INT_MAX, then they get the
current maximum; anything else greater than max_backlog or anything
negative incurs EINVAL.
The limit on the maximum queue size can be set by:
echo N >/proc/sys/net/rxrpc/max_backlog
where 4<=N<=32.
Further, set the default backlog to 0, requiring listen() to be called
before we start actually queueing new calls. Whilst this kind of is a
change in the UAPI, the caller can't actually *accept* new calls anyway
unless they've first called listen() to put the socket into the LISTENING
state - thus the aforementioned new calls would otherwise just sit there,
eating up kernel memory. (Note that sockets that don't have a non-zero
service ID bound don't get incoming calls anyway.)
Given that the default backlog is now 0, make the AFS filesystem call
kernel_listen() to set the maximum backlog for itself.
Possible improvements include:
(1) Trimming a too-large backlog to max_backlog when listen is called.
(2) Trimming the backlog value whenever the value is used so that changes
to max_backlog are applied to an open socket automatically. Note that
the AFS filesystem opens one socket and keeps it open for extended
periods, so would miss out on changes to max_backlog.
(3) Having a separate setting for the AFS filesystem.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Conflicts:
net/sched/act_police.c
net/sched/sch_drr.c
net/sched/sch_hfsc.c
net/sched/sch_prio.c
net/sched/sch_red.c
net/sched/sch_tbf.c
In net-next the drop methods of the packet schedulers got removed, so
the bug fixes to them in 'net' are irrelevant.
A packet action unload crash fix conflicts with the addition of the
new firstuse timestamp.
Signed-off-by: David S. Miller <davem@davemloft.net>
Simplify the RxRPC connect() implementation. It will just note the
destination address it is given, and if a sendmsg() comes along with no
address, this will be assigned as the address. No transport struct will be
held internally, which will allow us to remove this later.
Simplify sendmsg() also. Whilst a call is active, userspace refers to it
by a private unique user ID specified in a control message. When sendmsg()
sees a user ID that doesn't map to an extant call, it creates a new call
for that user ID and attempts to add it. If, when we try to add it, the
user ID is now registered, we now reject the message with -EEXIST. We
should never see this situation unless two threads are racing, trying to
create a call with the same ID - which would be an error.
It also isn't required to provide sendmsg() with an address - provided the
control message data holds a user ID that maps to a currently active call.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/rxrpc/rxkad.c:1165:1-3: WARNING: PTR_ERR_OR_ZERO can be used
Use PTR_ERR_OR_ZERO rather than if(IS_ERR(...)) + PTR_ERR
Generated by: scripts/coccinelle/api/ptr_ret.cocci
CC: David Howells <dhowells@redhat.com>
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
David Howells