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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>
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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>
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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: be6e6707f6ee ("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>
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Use the peer record to distribute network errors rather than the transport
object (which I want to get rid of). An error from a particular peer
terminates all calls on that peer.
For future consideration:
(1) For ICMP-induced errors it might be worth trying to extract the RxRPC
header from the offending packet, if one is returned attached to the
ICMP packet, to better direct the error.
This may be overkill, though, since an ICMP packet would be expected
to be relating to the destination port, machine or network. RxRPC
ABORT and BUSY packets give notice at RxRPC level.
(2) To also abort connection-level communications (such as CHALLENGE
packets) where indicted by an error - but that requires some revamping
of the connection event handling first.
Signed-off-by: David Howells <dhowells@redhat.com>
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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>
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Rename files matching net/rxrpc/ar-*.c to get rid of the "ar-" prefix.
This will aid splitting those files by making easier to come up with new
names.
Note that the not all files are simply renamed from ar-X.c to X.c. The
following exceptions are made:
(*) ar-call.c -> call_object.c
ar-ack.c -> call_event.c
call_object.c is going to contain the core of the call object
handling. Call event handling is all going to be in call_event.c.
(*) ar-accept.c -> call_accept.c
Incoming call handling is going to be here.
(*) ar-connection.c -> conn_object.c
ar-connevent.c -> conn_event.c
The former file is going to have the basic connection object handling,
but there will likely be some differentiation between client
connections and service connections in additional files later. The
latter file will have all the connection-level event handling.
(*) ar-local.c -> local_object.c
This will have the local endpoint object handling code. The local
endpoint event handling code will later be split out into
local_event.c.
(*) ar-peer.c -> peer_object.c
This will have the peer endpoint object handling code. Peer event
handling code will be placed in peer_event.c (for the moment, there is
none).
(*) ar-error.c -> peer_event.c
This will become the peer event handling code, though for the moment
it's actually driven from the local endpoint's perspective.
Note that I haven't renamed ar-transport.c to transport_object.c as the
intention is to delete it when the rxrpc_transport struct is excised.
The only file that actually has its contents changed is net/rxrpc/Makefile.
net/rxrpc/ar-internal.h will need its section marker comments updating, but
I'll do that in a separate patch to make it easier for git to follow the
history across the rename. I may also want to rename ar-internal.h at some
point - but that would mean updating all the #includes and I'd rather do
that in a separate step.
Signed-off-by: David Howells <dhowells@redhat.com.
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David Howells
Arnd Bergmann