Commit Graph

36 Commits

Author SHA1 Message Date
David Howells f7aec129a3 rxrpc: Cache the congestion window setting
Cache the congestion window setting that was determined during a call's
transmission phase when it finishes so that it can be used by the next call
to the same peer, thereby shortcutting the slow-start algorithm.

The value is stored in the rxrpc_peer struct and is accessed without
locking.  Each call takes the value that happens to be there when it starts
and just overwrites the value when it finishes.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-06-14 15:42:45 -04:00
David Howells 4722974d90 rxrpc: Implement service upgrade
Implement AuriStor's service upgrade facility.  There are three problems
that this is meant to deal with:

 (1) Various of the standard AFS RPC calls have IPv4 addresses in their
     requests and/or replies - but there's no room for including IPv6
     addresses.

 (2) Definition of IPv6-specific RPC operations in the standard operation
     sets has not yet been achieved.

 (3) One could envision the creation a new service on the same port that as
     the original service.  The new service could implement improved
     operations - and the client could try this first, falling back to the
     original service if it's not there.

     Unfortunately, certain servers ignore packets addressed to a service
     they don't implement and don't respond in any way - not even with an
     ABORT.  This means that the client must then wait for the call timeout
     to occur.

What service upgrade does is to see if the connection is marked as being
'upgradeable' and if so, change the service ID in the server and thus the
request and reply formats.  Note that the upgrade isn't mandatory - a
server that supports only the original call set will ignore the upgrade
request.

In the protocol, the procedure is then as follows:

 (1) To request an upgrade, the first DATA packet in a new connection must
     have the userStatus set to 1 (this is normally 0).  The userStatus
     value is normally ignored by the server.

 (2) If the server doesn't support upgrading, the reply packets will
     contain the same service ID as for the first request packet.

 (3) If the server does support upgrading, all future reply packets on that
     connection will contain the new service ID and the new service ID will
     be applied to *all* further calls on that connection as well.

 (4) The RPC op used to probe the upgrade must take the same request data
     as the shadow call in the upgrade set (but may return a different
     reply).  GetCapability RPC ops were added to all standard sets for
     just this purpose.  Ops where the request formats differ cannot be
     used for probing.

 (5) The client must wait for completion of the probe before sending any
     further RPC ops to the same destination.  It should then use the
     service ID that recvmsg() reported back in all future calls.

 (6) The shadow service must have call definitions for all the operation
     IDs defined by the original service.


To support service upgrading, a server should:

 (1) Call bind() twice on its AF_RXRPC socket before calling listen().
     Each bind() should supply a different service ID, but the transport
     addresses must be the same.  This allows the server to receive
     requests with either service ID.

 (2) Enable automatic upgrading by calling setsockopt(), specifying
     RXRPC_UPGRADEABLE_SERVICE and passing in a two-member array of
     unsigned shorts as the argument:

	unsigned short optval[2];

     This specifies a pair of service IDs.  They must be different and must
     match the service IDs bound to the socket.  Member 0 is the service ID
     to upgrade from and member 1 is the service ID to upgrade to.

Signed-off-by: David Howells <dhowells@redhat.com>
2017-06-05 14:30:49 +01:00
David Howells 28036f4485 rxrpc: Permit multiple service binding
Permit bind() to be called on an AF_RXRPC socket more than once (currently
maximum twice) to bind multiple listening services to it.  There are some
restrictions:

 (1) All bind() calls involved must have a non-zero service ID.

 (2) The service IDs must all be different.

 (3) The rest of the address (notably the transport part) must be the same
     in all (a single UDP socket is shared).

 (4) This must be done before listen() or sendmsg() is called.

This allows someone to connect to the service socket with different service
IDs and lays the foundation for service upgrading.

The service ID used by an incoming call can be extracted from the msg_name
returned by recvmsg().

Signed-off-by: David Howells <dhowells@redhat.com>
2017-06-05 14:30:49 +01:00
David Howells 2baec2c3f8 rxrpc: Support network namespacing
Support network namespacing in AF_RXRPC with the following changes:

 (1) All the local endpoint, peer and call lists, locks, counters, etc. are
     moved into the per-namespace record.

 (2) All the connection tracking is moved into the per-namespace record
     with the exception of the client connection ID tree, which is kept
     global so that connection IDs are kept unique per-machine.

 (3) Each namespace gets its own epoch.  This allows each network namespace
     to pretend to be a separate client machine.

 (4) The /proc/net/rxrpc_xxx files are now called /proc/net/rxrpc/xxx and
     the contents reflect the namespace.

fs/afs/ should be okay with this patch as it explicitly requires the current
net namespace to be init_net to permit a mount to proceed at the moment.  It
will, however, need updating so that cells, IP addresses and DNS records are
per-namespace also.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-05-25 13:15:11 -04:00
David Howells 3a92789af0 rxrpc: Use negative error codes in rxrpc_call struct
Use negative error codes in struct rxrpc_call::error because that's what
the kernel normally deals with and to make the code consistent.  We only
turn them positive when transcribing into a cmsg for userspace recvmsg.

Signed-off-by: David Howells <dhowells@redhat.com>
2017-04-06 10:11:56 +01:00
David Howells 540b1c48c3 rxrpc: Fix deadlock between call creation and sendmsg/recvmsg
All the routines by which rxrpc is accessed from the outside are serialised
by means of the socket lock (sendmsg, recvmsg, bind,
rxrpc_kernel_begin_call(), ...) and this presents a problem:

 (1) If a number of calls on the same socket are in the process of
     connection to the same peer, a maximum of four concurrent live calls
     are permitted before further calls need to wait for a slot.

 (2) If a call is waiting for a slot, it is deep inside sendmsg() or
     rxrpc_kernel_begin_call() and the entry function is holding the socket
     lock.

 (3) sendmsg() and recvmsg() or the in-kernel equivalents are prevented
     from servicing the other calls as they need to take the socket lock to
     do so.

 (4) The socket is stuck until a call is aborted and makes its slot
     available to the waiter.

Fix this by:

 (1) Provide each call with a mutex ('user_mutex') that arbitrates access
     by the users of rxrpc separately for each specific call.

 (2) Make rxrpc_sendmsg() and rxrpc_recvmsg() unlock the socket as soon as
     they've got a call and taken its mutex.

     Note that I'm returning EWOULDBLOCK from recvmsg() if MSG_DONTWAIT is
     set but someone else has the lock.  Should I instead only return
     EWOULDBLOCK if there's nothing currently to be done on a socket, and
     sleep in this particular instance because there is something to be
     done, but we appear to be blocked by the interrupt handler doing its
     ping?

 (3) Make rxrpc_new_client_call() unlock the socket after allocating a new
     call, locking its user mutex and adding it to the socket's call tree.
     The call is returned locked so that sendmsg() can add data to it
     immediately.

     From the moment the call is in the socket tree, it is subject to
     access by sendmsg() and recvmsg() - even if it isn't connected yet.

 (4) Lock new service calls in the UDP data_ready handler (in
     rxrpc_new_incoming_call()) because they may already be in the socket's
     tree and the data_ready handler makes them live immediately if a user
     ID has already been preassigned.

     Note that the new call is locked before any notifications are sent
     that it is live, so doing mutex_trylock() *ought* to always succeed.
     Userspace is prevented from doing sendmsg() on calls that are in a
     too-early state in rxrpc_do_sendmsg().

 (5) Make rxrpc_new_incoming_call() return the call with the user mutex
     held so that a ping can be scheduled immediately under it.

     Note that it might be worth moving the ping call into
     rxrpc_new_incoming_call() and then we can drop the mutex there.

 (6) Make rxrpc_accept_call() take the lock on the call it is accepting and
     release the socket after adding the call to the socket's tree.  This
     is slightly tricky as we've dequeued the call by that point and have
     to requeue it.

     Note that requeuing emits a trace event.

 (7) Make rxrpc_kernel_send_data() and rxrpc_kernel_recv_data() take the
     new mutex immediately and don't bother with the socket mutex at all.

This patch has the nice bonus that calls on the same socket are now to some
extent parallelisable.

Note that we might want to move rxrpc_service_prealloc() calls out from the
socket lock and give it its own lock, so that we don't hang progress in
other calls because we're waiting for the allocator.

We probably also want to avoid calling rxrpc_notify_socket() from within
the socket lock (rxrpc_accept_call()).

Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Marc Dionne <marc.c.dionne@auristor.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-03-01 09:50:58 -08:00
David Howells 210f035316 rxrpc: Allow listen(sock, 0) to be used to disable listening
Allow listen() with a backlog of 0 to be used to disable listening on an
AF_RXRPC socket.  This also releases any preallocation, thereby making it
easier for a kernel service to account for all allocated call structures
when shutting down the service.

The socket cannot thereafter have listening reenabled, but must rather be
closed and reopened.

Signed-off-by: David Howells <dhowells@redhat.com>
2017-01-09 11:10:02 +00:00
David Howells 26cb02aa6d rxrpc: Fix warning by splitting rxrpc_send_call_packet()
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>
2016-10-06 08:11:49 +01:00
David Howells 7212a57e8e rxrpc: Fix oops on incoming call to serviceless endpoint
If an call comes in to a local endpoint that isn't listening for any
incoming calls at the moment, an oops will happen.  We need to check that
the local endpoint's service pointer isn't NULL before we dereference it.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-10-06 08:11:49 +01:00
David Howells 1e9e5c9521 rxrpc: Reduce the rxrpc_local::services list to a pointer
Reduce the rxrpc_local::services list to just a pointer as we don't permit
multiple service endpoints to bind to a single transport endpoints (this is
excluded by rxrpc_lookup_local()).

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

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-29 22:57:47 +01:00
David Howells 58dc63c998 rxrpc: Add a tracepoint to follow packets in the Rx buffer
Add a tracepoint to follow the life of packets that get added to a call's
receive buffer.

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

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-17 11:24:03 +01:00
David Howells e6f3afb3fc rxrpc: Record calls that need to be accepted
Record calls that need to be accepted using sk_acceptq_added() otherwise
the backlog counter goes negative because sk_acceptq_removed() is called.
This causes the preallocator to malfunction.

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

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-17 10:51:54 +01:00
David Howells 3432a757b1 rxrpc: Fix prealloc refcounting
The preallocated call buffer holds a ref on the calls within that buffer.
The ref was being released in the wrong place - it worked okay for incoming
calls to the AFS cache manager service, but doesn't work right for incoming
calls to a userspace service.

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

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

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

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

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

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

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

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

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-13 22:38:30 +01:00
David Howells b25de36053 rxrpc: Add missing unlock in rxrpc_call_accept()
Add a missing unlock in rxrpc_call_accept() in the path taken if there's no
call to wake up.

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

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

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

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

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

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

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

To make this work, the following changes are made:

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

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

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

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

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

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

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

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

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

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

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

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

Additional changes:

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

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

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

Future additional changes that will need to be considered:

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

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

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

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

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

To this end:

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

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

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

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

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

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

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

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

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

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

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

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-08 11:10:11 +01:00
David Howells 8d94aa381d rxrpc: Calls shouldn't hold socket refs
rxrpc calls shouldn't hold refs on the sock struct.  This was done so that
the socket wouldn't go away whilst the call was in progress, such that the
call could reach the socket's queues.

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

To make this work, we do:

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

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

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

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

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

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

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

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

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

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

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

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

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

 (1) A socket's user ID tree.

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

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

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

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

Whilst we're at it, we can do:

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

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

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

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

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

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

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-07 15:33:20 +01:00
David Howells fff72429c2 rxrpc: Improve the call tracking tracepoint
Improve the call tracking tracepoint by showing more differentiation
between some of the put and get events, including:

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

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

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

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

Signed-off-by: David Howells <dhowells@redhat.com>
2016-09-07 15:30:22 +01:00
David Howells d001648ec7 rxrpc: Don't expose skbs to in-kernel users [ver #2]
Don't expose skbs to in-kernel users, such as the AFS filesystem, but
instead provide a notification hook the indicates that a call needs
attention and another that indicates that there's a new call to be
collected.

This makes the following possibilities more achievable:

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

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

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

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

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

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

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

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

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

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

Five interface functions have been removed:

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

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

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-09-01 16:43:27 -07:00
David Howells e34d4234b0 rxrpc: Trace rxrpc_call usage
Add a trace event for debuging rxrpc_call struct usage.

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

Helpers are provided to simplify this.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-08-30 15:58:31 +01:00
David Howells df844fd46b rxrpc: Use a tracepoint for skb accounting debugging
Use a tracepoint to log various skb accounting points to help in debugging
refcounting errors.

Signed-off-by: David Howells <dhowells@redhat.com>
2016-08-23 15:27:24 +01:00
David Howells 372ee16386 rxrpc: Fix races between skb free, ACK generation and replying
Inside the kafs filesystem it is possible to occasionally have a call
processed and terminated before we've had a chance to check whether we need
to clean up the rx queue for that call because afs_send_simple_reply() ends
the call when it is done, but this is done in a workqueue item that might
happen to run to completion before afs_deliver_to_call() completes.

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

To this end, the following changes are made:

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

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

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

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

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

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

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

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

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

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

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

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

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

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

     becomes:

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

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

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

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

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-08-06 00:08:40 -04:00
David Howells d991b4a32f rxrpc: Move peer lookup from call-accept to new-incoming-conn
Move the lookup of a peer from a call that's being accepted into the
function that creates a new incoming connection.  This will allow us to
avoid incrementing the peer's usage count in some cases in future.

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

Signed-off-by: David Howells <dhowells@redhat.com>
2016-07-06 10:49:57 +01:00
David Howells 2c4579e4b1 rxrpc: Move usage count getting into rxrpc_queue_conn()
Rather than calling rxrpc_get_connection() manually before calling
rxrpc_queue_conn(), do it inside the queue wrapper.

This allows us to do some important fixes:

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

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

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

And another useful changes:

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

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

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

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

Signed-off-by: David Howells <dhowells@redhat.com>
2016-07-06 10:43:51 +01:00
David Howells aa390bbe21 rxrpc: Kill off the rxrpc_transport struct
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>
2016-06-22 14:00:23 +01:00
David Howells 5627cc8b96 rxrpc: Provide more refcount helper functions
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>
2016-06-22 09:17:51 +01:00
David Howells 42886ffe77 rxrpc: Pass sk_buff * rather than rxrpc_host_header * to functions
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>
2016-06-22 09:10:01 +01:00
Dan Carpenter 0e4699e4a3 rxrpc: checking for IS_ERR() instead of NULL
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>
2016-06-22 09:09:58 +01:00
David Howells 4f95dd78a7 rxrpc: Rework local endpoint management
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>
2016-06-15 15:38:17 +01:00
David Howells be6e6707f6 rxrpc: Rework peer object handling to use hash table and RCU
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>
2016-06-15 10:12:33 +01:00
David Howells 8c3e34a4ff rxrpc: Rename files matching ar-*.c to git rid of the "ar-" prefix
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.
2016-06-13 12:16:05 +01:00