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Conflicts were easy to resolve using immediate context mostly,
except the cls_u32.c one where I simply too the entire HEAD
chunk.
Signed-off-by: David S. Miller <davem@davemloft.net>
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The rxrpc_input_packet() function and its call tree was built around the
assumption that data_ready() handler called from UDP to inform a kernel
service that there is data to be had was non-reentrant. This means that
certain locking could be dispensed with.
This, however, turns out not to be the case with a multi-queue network card
that can deliver packets to multiple cpus simultaneously. Each of those
cpus can be in the rxrpc_input_packet() function at the same time.
Fix by adding or changing some structure members:
(1) Add peer->rtt_input_lock to serialise access to the RTT buffer.
(2) Make conn->service_id into a 32-bit variable so that it can be
cmpxchg'd on all arches.
(3) Add call->input_lock to serialise access to the Rx/Tx state. Note
that although the Rx and Tx states are (almost) entirely separate,
there's no point completing the separation and having separate locks
since it's a bi-phasal RPC protocol rather than a bi-direction
streaming protocol. Data transmission and data reception do not take
place simultaneously on any particular call.
and making the following functional changes:
(1) In rxrpc_input_data(), hold call->input_lock around the core to
prevent simultaneous producing of packets into the Rx ring and
updating of tracking state for a particular call.
(2) In rxrpc_input_ping_response(), only read call->ping_serial once, and
check it before checking RXRPC_CALL_PINGING as that's a cheaper test.
The bit test and bit clear can then be combined. No further locking
is needed here.
(3) In rxrpc_input_ack(), take call->input_lock after we've parsed much of
the ACK packet. The superseded ACK check is then done both before and
after the lock is taken.
The handing of ackinfo data is split, parsing before the lock is taken
and processing with it held. This is keyed on rxMTU being non-zero.
Congestion management is also done within the locked section.
(4) In rxrpc_input_ackall(), take call->input_lock around the Tx window
rotation. The ACKALL packet carries no information and is only really
useful after all packets have been transmitted since it's imprecise.
(5) In rxrpc_input_implicit_end_call(), we use rx->incoming_lock to
prevent calls being simultaneously implicitly ended on two cpus and
also to prevent any races with incoming call setup.
(6) In rxrpc_input_packet(), use cmpxchg() to effect the service upgrade
on a connection. It is only permitted to happen once for a
connection.
(7) In rxrpc_new_incoming_call(), we have to recheck the routing inside
rx->incoming_lock to see if someone else set up the call, connection
or peer whilst we were getting there. We can't trust the values from
the earlier routing check unless we pin refs on them - which we want
to avoid.
Further, we need to allow for an incoming call to have its state
changed on another CPU between us making it live and us adjusting it
because the conn is now in the RXRPC_CONN_SERVICE state.
(8) In rxrpc_peer_add_rtt(), take peer->rtt_input_lock around the access
to the RTT buffer. Don't need to lock around setting peer->rtt.
For reference, the inventory of state-accessing or state-altering functions
used by the packet input procedure is:
> rxrpc_input_packet()
* PACKET CHECKING
* ROUTING
> rxrpc_post_packet_to_local()
> rxrpc_find_connection_rcu() - uses RCU
> rxrpc_lookup_peer_rcu() - uses RCU
> rxrpc_find_service_conn_rcu() - uses RCU
> idr_find() - uses RCU
* CONNECTION-LEVEL PROCESSING
- Service upgrade
- Can only happen once per conn
! Changed to use cmpxchg
> rxrpc_post_packet_to_conn()
- Setting conn->hi_serial
- Probably safe not using locks
- Maybe use cmpxchg
* CALL-LEVEL PROCESSING
> Old-call checking
> rxrpc_input_implicit_end_call()
> rxrpc_call_completed()
> rxrpc_queue_call()
! Need to take rx->incoming_lock
> __rxrpc_disconnect_call()
> rxrpc_notify_socket()
> rxrpc_new_incoming_call()
- Uses rx->incoming_lock for the entire process
- Might be able to drop this earlier in favour of the call lock
> rxrpc_incoming_call()
! Conflicts with rxrpc_input_implicit_end_call()
> rxrpc_send_ping()
- Don't need locks to check rtt state
> rxrpc_propose_ACK
* PACKET DISTRIBUTION
> rxrpc_input_call_packet()
> rxrpc_input_data()
* QUEUE DATA PACKET ON CALL
> rxrpc_reduce_call_timer()
- Uses timer_reduce()
! Needs call->input_lock()
> rxrpc_receiving_reply()
! Needs locking around ack state
> rxrpc_rotate_tx_window()
> rxrpc_end_tx_phase()
> rxrpc_proto_abort()
> rxrpc_input_dup_data()
- Fills the Rx buffer
- rxrpc_propose_ACK()
- rxrpc_notify_socket()
> rxrpc_input_ack()
* APPLY ACK PACKET TO CALL AND DISCARD PACKET
> rxrpc_input_ping_response()
- Probably doesn't need any extra locking
! Need READ_ONCE() on call->ping_serial
> rxrpc_input_check_for_lost_ack()
- Takes call->lock to consult Tx buffer
> rxrpc_peer_add_rtt()
! Needs to take a lock (peer->rtt_input_lock)
! Could perhaps manage with cmpxchg() and xadd() instead
> rxrpc_input_requested_ack
- Consults Tx buffer
! Probably needs a lock
> rxrpc_peer_add_rtt()
> rxrpc_propose_ack()
> rxrpc_input_ackinfo()
- Changes call->tx_winsize
! Use cmpxchg to handle change
! Should perhaps track serial number
- Uses peer->lock to record MTU specification changes
> rxrpc_proto_abort()
! Need to take call->input_lock
> rxrpc_rotate_tx_window()
> rxrpc_end_tx_phase()
> rxrpc_input_soft_acks()
- Consults the Tx buffer
> rxrpc_congestion_management()
- Modifies the Tx annotations
! Needs call->input_lock()
> rxrpc_queue_call()
> rxrpc_input_abort()
* APPLY ABORT PACKET TO CALL AND DISCARD PACKET
> rxrpc_set_call_completion()
> rxrpc_notify_socket()
> rxrpc_input_ackall()
* APPLY ACKALL PACKET TO CALL AND DISCARD PACKET
! Need to take call->input_lock
> rxrpc_rotate_tx_window()
> rxrpc_end_tx_phase()
> rxrpc_reject_packet()
There are some functions used by the above that queue the packet, after
which the procedure is terminated:
- rxrpc_post_packet_to_local()
- local->event_queue is an sk_buff_head
- local->processor is a work_struct
- rxrpc_post_packet_to_conn()
- conn->rx_queue is an sk_buff_head
- conn->processor is a work_struct
- rxrpc_reject_packet()
- local->reject_queue is an sk_buff_head
- local->processor is a work_struct
And some that offload processing to process context:
- rxrpc_notify_socket()
- Uses RCU lock
- Uses call->notify_lock to call call->notify_rx
- Uses call->recvmsg_lock to queue recvmsg side
- rxrpc_queue_call()
- call->processor is a work_struct
- rxrpc_propose_ACK()
- Uses call->lock to wrap __rxrpc_propose_ACK()
And a bunch that complete a call, all of which use call->state_lock to
protect the call state:
- rxrpc_call_completed()
- rxrpc_set_call_completion()
- rxrpc_abort_call()
- rxrpc_proto_abort()
- Also uses rxrpc_queue_call()
Fixes: 17926a79320a ("[AF_RXRPC]: Provide secure RxRPC sockets for use by userspace and kernel both")
Signed-off-by: David Howells <dhowells@redhat.com>
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Move the out-of-order and duplicate ACK packet check to before the call to
rxrpc_input_ackinfo() so that the receive window size and MTU size are only
checked in the latest ACK packet and don't regress.
Fixes: 248f219cb8bc ("rxrpc: Rewrite the data and ack handling code")
Signed-off-by: David Howells <dhowells@redhat.com>
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Carry the call state out of the locked section in rxrpc_rotate_tx_window()
rather than sampling it afterwards. This is only used to select tracepoint
data, but could have changed by the time we do the tracepoint.
Signed-off-by: David Howells <dhowells@redhat.com>
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We should only call the function to end a call's Tx phase if we rotated the
marked-last packet out of the transmission buffer.
Make rxrpc_rotate_tx_window() return an indication of whether it just
rotated the packet marked as the last out of the transmit buffer, carrying
the information out of the locked section in that function.
We can then check the return value instead of examining RXRPC_CALL_TX_LAST.
Fixes: 70790dbe3f66 ("rxrpc: Pass the last Tx packet marker in the annotation buffer")
Signed-off-by: David Howells <dhowells@redhat.com>
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We don't need to take the RCU read lock in the rxrpc packet receive
function because it's held further up the stack in the IP input routine
around the UDP receive routines.
Fix this by dropping the RCU read lock calls from rxrpc_input_packet().
This simplifies the code.
Fixes: 70790dbe3f66 ("rxrpc: Pass the last Tx packet marker in the annotation buffer")
Signed-off-by: David Howells <dhowells@redhat.com>
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Use the UDP encap_rcv hook to cut the bit out of the rxrpc packet reception
in which a packet is placed onto the UDP receive queue and then immediately
removed again by rxrpc. Going via the queue in this manner seems like it
should be unnecessary.
This does, however, require the invention of a value to place in encap_type
as that's one of the conditions to switch packets out to the encap_rcv
hook. Possibly the value doesn't actually matter for anything other than
sockopts on the UDP socket, which aren't accessible outside of rxrpc
anyway.
This seems to cut a bit of time out of the time elapsed between each
sk_buff being timestamped and turning up in rxrpc (the final number in the
following trace excerpts). I measured this by making the rxrpc_rx_packet
trace point print the time elapsed between the skb being timestamped and
the current time (in ns), e.g.:
... 424.278721: rxrpc_rx_packet: ... ACK 25026
So doing a 512MiB DIO read from my test server, with an unmodified kernel:
N min max sum mean stddev
27605 2626 7581 7.83992e+07 2840.04 181.029
and with the patch applied:
N min max sum mean stddev
27547 1895 12165 6.77461e+07 2459.29 255.02
Signed-off-by: David Howells <dhowells@redhat.com>
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Fix the rxrpc_data_ready() function to pick up all packets and to not miss
any. There are two problems:
(1) The sk_data_ready pointer on the UDP socket is set *after* it is
bound. This means that it's open for business before we're ready to
dequeue packets and there's a tiny window exists in which a packet can
sneak onto the receive queue, but we never know about it.
Fix this by setting the pointers on the socket prior to binding it.
(2) skb_recv_udp() will return an error (such as ENETUNREACH) if there was
an error on the transmission side, even though we set the
sk_error_report hook. Because rxrpc_data_ready() returns immediately
in such a case, it never actually removes its packet from the receive
queue.
Fix this by abstracting out the UDP dequeuing and checksumming into a
separate function that keeps hammering on skb_recv_udp() until it
returns -EAGAIN, passing the packets extracted to the remainder of the
function.
and two potential problems:
(3) It might be possible in some circumstances or in the future for
packets to be being added to the UDP receive queue whilst rxrpc is
running consuming them, so the data_ready() handler might get called
less often than once per packet.
Allow for this by fully draining the queue on each call as (2).
(4) If a packet fails the checksum check, the code currently returns after
discarding the packet without checking for more.
Allow for this by fully draining the queue on each call as (2).
Fixes: 17926a79320a ("[AF_RXRPC]: Provide secure RxRPC sockets for use by userspace and kernel both")
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
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Fix some refs to init_net that should've been changed to the appropriate
network namespace.
Fixes: 2baec2c3f854 ("rxrpc: Support network namespacing")
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
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rxrpc_lose_skb() is now exactly the same as rxrpc_free_skb(), so remove it
and use the latter instead.
Signed-off-by: David Howells <dhowells@redhat.com>
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Minor conflict in net/core/rtnetlink.c, David Ahern's bug fix in 'net'
overlapped the renaming of a netlink attribute in net-next.
Signed-off-by: David S. Miller <davem@davemloft.net>
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Make the following changes to improve the robustness of the code that sets
up a new service call:
(1) Cache the rxrpc_sock struct obtained in rxrpc_data_ready() to do a
service ID check and pass that along to rxrpc_new_incoming_call().
This means that I can remove the check from rxrpc_new_incoming_call()
without the need to worry about the socket attached to the local
endpoint getting replaced - which would invalidate the check.
(2) Cache the rxrpc_peer struct, thereby allowing the peer search to be
done once. The peer is passed to rxrpc_new_incoming_call(), thereby
saving the need to repeat the search.
This also reduces the possibility of rxrpc_publish_service_conn()
BUG()'ing due to the detection of a duplicate connection, despite the
initial search done by rxrpc_find_connection_rcu() having turned up
nothing.
This BUG() shouldn't ever get hit since rxrpc_data_ready() *should* be
non-reentrant and the result of the initial search should still hold
true, but it has proven possible to hit.
I *think* this may be due to __rxrpc_lookup_peer_rcu() cutting short
the iteration over the hash table if it finds a matching peer with a
zero usage count, but I don't know for sure since it's only ever been
hit once that I know of.
Another possibility is that a bug in rxrpc_data_ready() that checked
the wrong byte in the header for the RXRPC_CLIENT_INITIATED flag
might've let through a packet that caused a spurious and invalid call
to be set up. That is addressed in another patch.
(3) Fix __rxrpc_lookup_peer_rcu() to skip peer records that have a zero
usage count rather than stopping and returning not found, just in case
there's another peer record behind it in the bucket.
(4) Don't search the peer records in rxrpc_alloc_incoming_call(), but
rather either use the peer cached in (2) or, if one wasn't found,
preemptively install a new one.
Fixes: 8496af50eb38 ("rxrpc: Use RCU to access a peer's service connection tree")
Signed-off-by: David Howells <dhowells@redhat.com>
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Do more up-front checking on incoming packets to weed out invalid ones and
also ones aimed at services that we don't support.
Whilst we're at it, replace the clearing of call and skew if we don't find
a connection with just initialising the variables to zero at the top of the
function.
Signed-off-by: David Howells <dhowells@redhat.com>
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In the input path, a received sk_buff can be marked for rejection by
setting RXRPC_SKB_MARK_* in skb->mark and, if needed, some auxiliary data
(such as an abort code) in skb->priority. The rejection is handled by
queueing the sk_buff up for dealing with in process context. The output
code reads the mark and priority and, theoretically, generates an
appropriate response packet.
However, if RXRPC_SKB_MARK_BUSY is set, this isn't noticed and an ABORT
message with a random abort code is generated (since skb->priority wasn't
set to anything).
Fix this by outputting the appropriate sort of packet.
Also, whilst we're at it, most of the marks are no longer used, so remove
them and rename the remaining two to something more obvious.
Fixes: 248f219cb8bc ("rxrpc: Rewrite the data and ack handling code")
Signed-off-by: David Howells <dhowells@redhat.com>
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Fix RTT information gathering in AF_RXRPC by the following means:
(1) Enable Rx timestamping on the transport socket with SO_TIMESTAMPNS.
(2) If the sk_buff doesn't have a timestamp set when rxrpc_data_ready()
collects it, set it at that point.
(3) Allow ACKs to be requested on the last packet of a client call, but
not a service call. We need to be careful lest we undo:
bf7d620abf22c321208a4da4f435e7af52551a21
Author: David Howells <dhowells@redhat.com>
Date: Thu Oct 6 08:11:51 2016 +0100
rxrpc: Don't request an ACK on the last DATA packet of a call's Tx phase
but that only really applies to service calls that we're handling,
since the client side gets to send the final ACK (or not).
(4) When about to transmit an ACK or DATA packet, record the Tx timestamp
before only; don't update the timestamp afterwards.
(5) Switch the ordering between recording the serial and recording the
timestamp to always set the serial number first. The serial number
shouldn't be seen referenced by an ACK packet until we've transmitted
the packet bearing it - so in the Rx path, we don't need the timestamp
until we've checked the serial number.
Fixes: cf1a6474f807 ("rxrpc: Add per-peer RTT tracker")
Signed-off-by: David Howells <dhowells@redhat.com>
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There's a check in rxrpc_data_ready() that's checking the CLIENT_INITIATED
flag in the packet type field rather than in the packet flags field.
Fix this by creating a pair of helper functions to check whether the packet
is going to the client or to the server and use them generally.
Fixes: 248f219cb8bc ("rxrpc: Rewrite the data and ack handling code")
Signed-off-by: David Howells <dhowells@redhat.com>
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An SKB is not on a list if skb->next is NULL.
Codify this convention into a helper function and use it
where we are dequeueing an SKB and need to mark it as such.
Signed-off-by: David S. Miller <davem@davemloft.net>
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Trace notifications from the softirq side of the socket to the
process-context side.
Signed-off-by: David Howells <dhowells@redhat.com>
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Trace successful packet transmission (kernel_sendmsg() succeeded, that is)
in AF_RXRPC. We can share the enum that defines the transmission points
with the trace_rxrpc_tx_fail() tracepoint, so rename its constants to be
applicable to both.
Also, save the internal call->debug_id in the rxrpc_channel struct so that
it can be used in retransmission trace lines.
Signed-off-by: David Howells <dhowells@redhat.com>
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Sometimes an in-progress call will stop responding on the fileserver when
the fileserver quietly cancels the call with an internally marked abort
(RX_CALL_DEAD), without sending an ABORT to the client.
This causes the client's call to eventually expire from lack of incoming
packets directed its way, which currently leads to it being cancelled
locally with ETIME. Note that it's not currently clear as to why this
happens as it's really hard to reproduce.
The rotation policy implement by kAFS, however, doesn't differentiate
between ETIME meaning we didn't get any response from the server and ETIME
meaning the call got cancelled mid-flow. The latter leads to an oops when
fetching data as the rotation partially resets the afs_read descriptor,
which can result in a cleared page pointer being dereferenced because that
page has already been filled.
Handle this by the following means:
(1) Set a flag on a call when we receive a packet for it.
(2) Store the highest packet serial number so far received for a call
(bearing in mind this may wrap).
(3) If, when the "not received anything recently" timeout expires on a
call, we've received at least one packet for a call and the connection
as a whole has received packets more recently than that call, then
cancel the call locally with ECONNRESET rather than ETIME.
This indicates that the call was definitely in progress on the server.
(4) In kAFS, if the rotation algorithm sees ECONNRESET rather than ETIME,
don't try the next server, but rather abort the call.
This avoids the oops as we don't try to reuse the afs_read struct.
Rather, as-yet ungotten pages will be reread at a later data.
Also:
(5) Add an rxrpc tracepoint to log detection of the call being reset.
Without this, I occasionally see an oops like the following:
general protection fault: 0000 [#1] SMP PTI
...
RIP: 0010:_copy_to_iter+0x204/0x310
RSP: 0018:ffff8800cae0f828 EFLAGS: 00010206
RAX: 0000000000000560 RBX: 0000000000000560 RCX: 0000000000000560
RDX: ffff8800cae0f968 RSI: ffff8800d58b3312 RDI: 0005080000000000
RBP: ffff8800cae0f968 R08: 0000000000000560 R09: ffff8800ca00f400
R10: ffff8800c36f28d4 R11: 00000000000008c4 R12: ffff8800cae0f958
R13: 0000000000000560 R14: ffff8800d58b3312 R15: 0000000000000560
FS: 00007fdaef108080(0000) GS:ffff8800ca680000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb28a8fa000 CR3: 00000000d2a76002 CR4: 00000000001606e0
Call Trace:
skb_copy_datagram_iter+0x14e/0x289
rxrpc_recvmsg_data.isra.0+0x6f3/0xf68
? trace_buffer_unlock_commit_regs+0x4f/0x89
rxrpc_kernel_recv_data+0x149/0x421
afs_extract_data+0x1e0/0x798
? afs_wait_for_call_to_complete+0xc9/0x52e
afs_deliver_fs_fetch_data+0x33a/0x5ab
afs_deliver_to_call+0x1ee/0x5e0
? afs_wait_for_call_to_complete+0xc9/0x52e
afs_wait_for_call_to_complete+0x12b/0x52e
? wake_up_q+0x54/0x54
afs_make_call+0x287/0x462
? afs_fs_fetch_data+0x3e6/0x3ed
? rcu_read_lock_sched_held+0x5d/0x63
afs_fs_fetch_data+0x3e6/0x3ed
afs_fetch_data+0xbb/0x14a
afs_readpages+0x317/0x40d
__do_page_cache_readahead+0x203/0x2ba
? ondemand_readahead+0x3a7/0x3c1
ondemand_readahead+0x3a7/0x3c1
generic_file_buffered_read+0x18b/0x62f
__vfs_read+0xdb/0xfe
vfs_read+0xb2/0x137
ksys_read+0x50/0x8c
do_syscall_64+0x7d/0x1a0
entry_SYSCALL_64_after_hwframe+0x49/0xbe
Note the weird value in RDI which is a result of trying to kmap() a NULL
page pointer.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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The expect_rx_by call timeout is supposed to be set when a call is started
to indicate that we need to receive a packet by that point. This is
currently put back every time we receive a packet, but it isn't started
when we first send a packet. Without this, the call may wait forever if
the server doesn't deign to reply.
Fix this by setting the timeout upon a successful UDP sendmsg call for the
first DATA packet. The timeout is initiated only for initial transmission
and not for subsequent retries as we don't want the retry mechanism to
extend the timeout indefinitely.
Fixes: a158bdd3247b ("rxrpc: Fix call timeouts")
Reported-by: Marc Dionne <marc.dionne@auristor.com>
Signed-off-by: David Howells <dhowells@redhat.com>
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By analogy with other Rx implementations, RxRPC packet types 9, 10 and 11
should just be discarded rather than being aborted like other undefined
packet types.
Reported-by: Jeffrey Altman <jaltman@auristor.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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If a call-level abort is received for the previous call to complete on a
connection channel, then that abort is queued for the connection processor
to handle. Unfortunately, the connection processor then assumes without
checking that the abort is connection-level (ie. callNumber is 0) and
distributes it over all active calls on that connection, thereby
incorrectly aborting them.
Fix this by discarding aborts aimed at a completed call.
Further, discard all packets aimed at a call that's complete if there's
currently an active call on a channel, since the DATA packets associated
with the new call automatically terminate the old call.
Fixes: 18bfeba50dfd ("rxrpc: Perform terminal call ACK/ABORT retransmission from conn processor")
Reported-by: Marc Dionne <marc.dionne@auristor.com>
Signed-off-by: David Howells <dhowells@redhat.com>
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Fix the firewall route keepalive part of AF_RXRPC which is currently
function incorrectly by replying to VERSION REPLY packets from the server
with VERSION REQUEST packets.
Instead, send VERSION REPLY packets to the peers of service connections to
act as keep-alives 20s after the latest packet was transmitted to that
peer.
Also, just discard VERSION REPLY packets rather than replying to them.
Signed-off-by: David Howells <dhowells@redhat.com>
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In rxrpc and afs, use the debug_ids that are monotonically allocated to
various objects as they're allocated rather than pointers as kernel
pointers are now hashed making them less useful. Further, the debug ids
aren't reused anywhere nearly as quickly.
In addition, allow kernel services that use rxrpc, such as afs, to take
numbers from the rxrpc counter, assign them to their own call struct and
pass them in to rxrpc for both client and service calls so that the trace
lines for each will have the same ID tag.
Signed-off-by: David Howells <dhowells@redhat.com>
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Clean up some whitespace from rxrpc.
Signed-off-by: David Howells <dhowells@redhat.com>
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Add an extra timeout that is set/updated when we send a DATA packet that
has the request-ack flag set. This allows us to detect if we don't get an
ACK in response to the latest flagged packet.
The ACK packet is adjudged to have been lost if it doesn't turn up within
2*RTT of the transmission.
If the timeout occurs, we schedule the sending of a PING ACK to find out
the state of the other side. If a new DATA packet is ready to go sooner,
we cancel the sending of the ping and set the request-ack flag on that
instead.
If we get back a PING-RESPONSE ACK that indicates a lower tx_top than what
we had at the time of the ping transmission, we adjudge all the DATA
packets sent between the response tx_top and the ping-time tx_top to have
been lost and retransmit immediately.
Rather than sending a PING ACK, we could just pick a DATA packet and
speculatively retransmit that with request-ack set. It should result in
either a REQUESTED ACK or a DUPLICATE ACK which we can then use in lieu the
a PING-RESPONSE ACK mentioned above.
Signed-off-by: David Howells <dhowells@redhat.com>
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Fix the rxrpc call expiration timeouts and make them settable from
userspace. By analogy with other rx implementations, there should be three
timeouts:
(1) "Normal timeout"
This is set for all calls and is triggered if we haven't received any
packets from the peer in a while. It is measured from the last time
we received any packet on that call. This is not reset by any
connection packets (such as CHALLENGE/RESPONSE packets).
If a service operation takes a long time, the server should generate
PING ACKs at a duration that's substantially less than the normal
timeout so is to keep both sides alive. This is set at 1/6 of normal
timeout.
(2) "Idle timeout"
This is set only for a service call and is triggered if we stop
receiving the DATA packets that comprise the request data. It is
measured from the last time we received a DATA packet.
(3) "Hard timeout"
This can be set for a call and specified the maximum lifetime of that
call. It should not be specified by default. Some operations (such
as volume transfer) take a long time.
Allow userspace to set/change the timeouts on a call with sendmsg, using a
control message:
RXRPC_SET_CALL_TIMEOUTS
The data to the message is a number of 32-bit words, not all of which need
be given:
u32 hard_timeout; /* sec from first packet */
u32 idle_timeout; /* msec from packet Rx */
u32 normal_timeout; /* msec from data Rx */
This can be set in combination with any other sendmsg() that affects a
call.
Signed-off-by: David Howells <dhowells@redhat.com>
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Fix call expiry handling in the following ways
(1) If all the request data from a client call is acked, don't send a
follow up IDLE ACK with firstPacket == 1 and previousPacket == 0 as
this appears to fool some servers into thinking everything has been
accepted.
(2) Never send an abort back to the server once it has ACK'd all the
request packets; rather just try to reuse the channel for the next
call. The first request DATA packet of the next call on the same
channel will implicitly ACK the entire reply of the dead call - even
if we haven't transmitted it yet.
(3) Don't send RX_CALL_TIMEOUT in an ABORT packet, librx uses abort codes
to pass local errors to the caller in addition to remote errors, and
this is meant to be local only.
The following also need to be addressed in future patches:
(4) Service calls should send PING ACKs as 'keep alives' if the server is
still processing the call.
(5) VERSION REPLY packets should be sent to the peers of service
connections to act as keep-alives. This is used to keep firewall
routes in place. The AFS CM should enable this.
Signed-off-by: David Howells <dhowells@redhat.com>
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In preparation to enabling -Wimplicit-fallthrough, mark switch cases
where we are expecting to fall through.
Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Make it possible for a client to use AuriStor's service upgrade facility.
The client does this by adding an RXRPC_UPGRADE_SERVICE control message to
the first sendmsg() of a call. This takes no parameters.
When recvmsg() starts returning data from the call, the service ID field in
the returned msg_name will reflect the result of the upgrade attempt. If
the upgrade was ignored, srx_service will match what was set in the
sendmsg(); if the upgrade happened the srx_service will be altered to
indicate the service the server upgraded to.
Note that:
(1) The choice of upgrade service is up to the server
(2) Further client calls to the same server that would share a connection
are blocked if an upgrade probe is in progress.
(3) This should only be used to probe the service. Clients should then
use the returned service ID in all subsequent communications with that
server (and not set the upgrade). Note that the kernel will not
retain this information should the connection expire from its cache.
(4) If a server that supports upgrading is replaced by one that doesn't,
whilst a connection is live, and if the replacement is running, say,
OpenAFS 1.6.4 or older or an older IBM AFS, then the replacement
server will not respond to packets sent to the upgraded connection.
At this point, calls will time out and the server must be reprobed.
Signed-off-by: David Howells <dhowells@redhat.com>
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Add a tracepoint (rxrpc_rx_rwind_change) to log changes in a call's receive
window size as imposed by the peer through an ACK packet.
Signed-off-by: David Howells <dhowells@redhat.com>
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Add a tracepoint (rxrpc_rx_abort) to record received aborts.
Signed-off-by: David Howells <dhowells@redhat.com>
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Add a tracepoint (rxrpc_rx_proto) to record protocol errors in received
packets. The following changes are made:
(1) Add a function, __rxrpc_abort_eproto(), to note a protocol error on a
call and mark the call aborted. This is wrapped by
rxrpc_abort_eproto() that makes the why string usable in trace.
(2) Add trace_rxrpc_rx_proto() or rxrpc_abort_eproto() to protocol error
generation points, replacing rxrpc_abort_call() with the latter.
(3) Only send an abort packet in rxkad_verify_packet*() if we actually
managed to abort the call.
Note that a trace event is also emitted if a kernel user (e.g. afs) tries
to send data through a call when it's not in the transmission phase, though
it's not technically a receive event.
Signed-off-by: David Howells <dhowells@redhat.com>
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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>
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The RxRPC ACK packet may contain an extension that includes the peer's
current Rx window size for this call. We adjust the local Tx window size
to match. However, the transmitter can stall if the receive window is
reduced to 0 by the peer and then reopened.
This is because the normal way that the transmitter is re-energised is by
dropping something out of our Tx queue and thus making space. When a
single gap is made, the transmitter is woken up. However, because there's
nothing in the Tx queue at this point, this doesn't happen.
To fix this, perform a wake_up() any time we see the peer's Rx window size
increasing.
The observable symptom is that calls start failing on ETIMEDOUT and the
following:
kAFS: SERVER DEAD state=-62
appears in dmesg.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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The call state may be changed at any time by the data-ready routine in
response to received packets, so if the call state is to be read and acted
upon several times in a function, READ_ONCE() must be used unless the call
state lock is held.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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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>
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Add the following extra tracing information:
(1) Modify the rxrpc_transmit tracepoint to record the Tx window size as
this is varied by the slow-start algorithm.
(2) Modify the rxrpc_rx_ack tracepoint to record more information from
received ACK packets.
(3) Add an rxrpc_rx_data tracepoint to record the information in DATA
packets.
(4) Add an rxrpc_disconnect_call tracepoint to record call disconnection,
including the reason the call was disconnected.
(5) Add an rxrpc_improper_term tracepoint to record implicit termination
of a call by a client either by starting a new call on a particular
connection channel without first transmitting the final ACK for the
previous call.
Signed-off-by: David Howells <dhowells@redhat.com>
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Fix the way enum values are translated into strings in AF_RXRPC
tracepoints. The problem with just doing a lookup in a normal flat array
of strings or chars is that external tracing infrastructure can't find it.
Rather, TRACE_DEFINE_ENUM must be used.
Also sort the enums and string tables to make it easier to keep them in
order so that a future patch to __print_symbolic() can be optimised to try
a direct lookup into the table first before iterating over it.
A couple of _proto() macro calls are removed because they refered to tables
that got moved to the tracing infrastructure. The relevant data can be
found by way of tracing.
Signed-off-by: David Howells <dhowells@redhat.com>
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A new argument is added to __skb_recv_datagram to provide
an explicit skb destructor, invoked under the receive queue
lock.
The UDP protocol uses such argument to perform memory
reclaiming on dequeue, so that the UDP protocol does not
set anymore skb->desctructor.
Instead explicit memory reclaiming is performed at close() time and
when skbs are removed from the receive queue.
The in kernel UDP protocol users now need to call a
skb_recv_udp() variant instead of skb_recv_datagram() to
properly perform memory accounting on dequeue.
Overall, this allows acquiring only once the receive queue
lock on dequeue.
Tested using pktgen with random src port, 64 bytes packet,
wire-speed on a 10G link as sender and udp_sink as the receiver,
using an l4 tuple rxhash to stress the contention, and one or more
udp_sink instances with reuseport.
nr sinks vanilla patched
1 440 560
3 2150 2300
6 3650 3800
9 4450 4600
12 6250 6450
v1 -> v2:
- do rmem and allocated memory scheduling under the receive lock
- do bulk scheduling in first_packet_length() and in udp_destruct_sock()
- avoid the typdef for the dequeue callback
Suggested-by: Eric Dumazet <edumazet@google.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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OpenAFS doesn't always correctly terminate client calls that it makes -
this includes calls the OpenAFS servers make to the cache manager service.
It should end the client call with either:
(1) An ACK that has firstPacket set to one greater than the seq number of
the reply DATA packet with the LAST_PACKET flag set (thereby
hard-ACK'ing all packets). nAcks should be 0 and acks[] should be
empty (ie. no soft-ACKs).
(2) An ACKALL packet.
OpenAFS, though, may send an ACK packet with firstPacket set to the last
seq number or less and soft-ACKs listed for all packets up to and including
the last DATA packet.
The transmitter, however, is obliged to keep the call live and the
soft-ACK'd DATA packets around until they're hard-ACK'd as the receiver is
permitted to drop any merely soft-ACK'd packet and request retransmission
by sending an ACK packet with a NACK in it.
Further, OpenAFS will also terminate a client call by beginning the next
client call on the same connection channel. This implicitly completes the
previous call.
This patch handles implicit ACK of a call on a channel by the reception of
the first packet of the next call on that channel.
If another call doesn't come along to implicitly ACK a call, then we have
to time the call out. There are some bugs there that will be addressed in
subsequent patches.
Signed-off-by: David Howells <dhowells@redhat.com>
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Separate the output of PING ACKs from the output of other sorts of ACK so
that if we receive a PING ACK and schedule transmission of a PING RESPONSE
ACK, the response doesn't get cancelled by a PING ACK we happen to be
scheduling transmission of at the same time.
If a PING RESPONSE gets lost, the other side might just sit there waiting
for it and refuse to proceed otherwise.
Signed-off-by: David Howells <dhowells@redhat.com>
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When a reply is deemed lost, we send a ping to find out the other end
received all the request data packets we sent. This should be limited to
client calls and we shouldn't do this on service calls.
Signed-off-by: David Howells <dhowells@redhat.com>
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Keep that call timeouts as ktimes rather than jiffies so that they can be
expressed as functions of RTT.
Signed-off-by: David Howells <dhowells@redhat.com>
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The offset field in struct rxrpc_skb_priv is unnecessary as the value can
always be calculated.
Signed-off-by: David Howells <dhowells@redhat.com>
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When we receive an ACK from the peer that tells us what the peer's receive
window (rwind) is, we should reduce ssthresh to rwind if rwind is smaller
than ssthresh.
Signed-off-by: David Howells <dhowells@redhat.com>
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Switch to Congestion Avoidance mode at cwnd == ssthresh rather than relying
on cwnd getting incremented beyond ssthresh and the window size, the mode
being shifted and then cwnd being corrected.
We need to make sure we switch into CA mode so that we stop marking every
packet for ACK.
Signed-off-by: David Howells <dhowells@redhat.com>
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Note the serial number of the packet being ACK'd in the congestion
management trace rather than the serial number of the ACK packet. Whilst
the serial number of the ACK packet is useful for matching ACK packet in
the output of wireshark, the serial number that the ACK is in response to
is of more use in working out how different trace lines relate.
Signed-off-by: David Howells <dhowells@redhat.com>
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Implement RxRPC slow-start, which is similar to RFC 5681 for TCP. A
tracepoint is added to log the state of the congestion management algorithm
and the decisions it makes.
Notes:
(1) Since we send fixed-size DATA packets (apart from the final packet in
each phase), counters and calculations are in terms of packets rather
than bytes.
(2) The ACK packet carries the equivalent of TCP SACK.
(3) The FLIGHT_SIZE calculation in RFC 5681 doesn't seem particularly
suited to SACK of a small number of packets. It seems that, almost
inevitably, by the time three 'duplicate' ACKs have been seen, we have
narrowed the loss down to one or two missing packets, and the
FLIGHT_SIZE calculation ends up as 2.
(4) In rxrpc_resend(), if there was no data that apparently needed
retransmission, we transmit a PING ACK to ask the peer to tell us what
its Rx window state is.
Signed-off-by: David Howells <dhowells@redhat.com>
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