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Use spin_lock_irq(), not spin_lock_bh() to take the lock when accessing the
->attend_link() to stop a delay in the I/O thread due to an interrupt being
taken in the app thread whilst that holds the lock and vice versa.
Fixes: a2ea9a907260 ("rxrpc: Use irq-disabling spinlocks between app and I/O thread")
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Link: https://patch.msgid.link/2870146.1734037095@warthog.procyon.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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When an rxrpc call is in its transmission phase and is sending a lot of
packets, stalls occasionally occur that cause severe performance
degradation (eg. increasing the transmission time for a 256MiB payload from
0.7s to 2.5s over a 10G link).
rxrpc already implements TCP-style congestion control [RFC5681] and this
helps mitigate the effects, but occasionally we're missing a time event
that deals with a missing ACK, leading to a stall until the RTO expires.
Fix this by implementing RACK/TLP in rxrpc.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Where a spinlock is used by both the application thread and the I/O thread,
use irq-disabling locking so that an interrupt taken on the app thread
doesn't also slow down the I/O thread.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Starvation can happen in the rxrpc I/O thread because it goes back to the
top of the I/O loop after it does any one thing without trying to give any
other connection or call CPU time. Also, because it processes one call
packet at a time, it tries to do the retransmission loop after each ACK
without checking to see if there are other ACKs already in the queue that
can update the SACK state.
Fix this by:
(1) Add a received-packet queue on each call.
(2) Distribute packets from the master Rx queue to the individual call,
conn and error queues and 'poking' calls to add them to the attend
queue first thing in the I/O thread.
(3) Go through all the attention-seeking connections and calls before
going back to the top of the I/O thread. Each queue is extracted as a
whole and then gone through so that new additions to insert themselves
into the queue.
(4) Make the call event handler go through all the packets currently on
the call's rx_queue before transmitting and retransmitting DATA
packets.
(5) Drop the skb argument from the call event handler as this is now
replaced with the rx_queue. Instead, keep track of whether we
received a packet or an ACK for the tests that used to rely on that.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Link: https://patch.msgid.link/20241204074710.990092-14-dhowells@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Implement path-MTU probing (along the lines of RFC8899) by padding some of
the PING ACKs we send. PING ACKs get their own individual responses quite
apart from the acking of data (though, as ACKs, they fulfil that role
also).
The probing concentrates on packet sizes that correspond how many
subpackets can be stuffed inside a jumbo packet as jumbo DATA packets are
just aggregations of individual DATA packets and can be split easily for
retransmission purposes.
If we want to perform probing, we advertise this by setting the maximum
number of jumbo subpackets to 0 in the ack trailer when we send an ACK and
see if the peer is also advertising the service. This is interpreted by
non-supporting Rx stacks as an indication that jumbo packets aren't
supported.
The MTU sizes advertised in the ACK trailer AF_RXRPC transmits are pegged
at a maximum of 1444 unless pmtud is supported by both sides.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Link: https://patch.msgid.link/20241204074710.990092-10-dhowells@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Use umin() and umax() rather than min_t()/max_t() where the type specified
is an unsigned type.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Link: https://patch.msgid.link/20241204074710.990092-4-dhowells@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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In rxrpc_open_socket(), it sets up the socket and then sets up the I/O
thread that will handle it. This is a problem, however, as there's a gap
between the two phases in which a packet may come into rxrpc_encap_rcv()
from the UDP packet but we oops when trying to wake the not-yet created I/O
thread.
As a quick fix, just make rxrpc_encap_rcv() discard the packet if there's
no I/O thread yet.
A better, but more intrusive fix would perhaps be to rearrange things such
that the socket creation is done by the I/O thread.
Fixes: a275da62e8c1 ("rxrpc: Create a per-local endpoint receive queue and I/O thread")
Signed-off-by: David Howells <dhowells@redhat.com>
cc: yuxuanzhe@outlook.com
cc: Marc Dionne <marc.dionne@auristor.com>
cc: Simon Horman <horms@kernel.org>
cc: linux-afs@lists.infradead.org
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20241001132702.3122709-2-dhowells@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Extract useful fields from a received ACK packet into the skb private data
early on in the process of parsing incoming packets. This makes the ACK
fields available even before we've matched the ACK up to a call and will
allow us to deal with path MTU discovery probe responses even after the
relevant call has been completed.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: "David S. Miller" <davem@davemloft.net>
cc: Eric Dumazet <edumazet@google.com>
cc: Jakub Kicinski <kuba@kernel.org>
cc: Paolo Abeni <pabeni@redhat.com>
cc: linux-afs@lists.infradead.org
cc: netdev@vger.kernel.org
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If CONFIG_AF_RXRPC_DEBUG_RX_DELAY=y, then a delay is injected between
packets and errors being received and them being made available to the
processing code, thereby allowing the RTT to be artificially increased.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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Move the connection setup of client calls to the I/O thread so that a whole
load of locking and barrierage can be eliminated. This necessitates the
app thread waiting for connection to complete before it can begin
encrypting data.
This also completes the fix for a race that exists between call connection
and call disconnection whereby the data transmission code adds the call to
the peer error distribution list after the call has been disconnected (say
by the rxrpc socket getting closed).
The fix is to complete the process of moving call connection, data
transmission and call disconnection into the I/O thread and thus forcibly
serialising them.
Note that the issue may predate the overhaul to an I/O thread model that
were included in the merge window for v6.2, but the timing is very much
changed by the change given below.
Fixes: cf37b5987508 ("rxrpc: Move DATA transmission into call processor work item")
Reported-by: syzbot+c22650d2844392afdcfd@syzkaller.appspotmail.com
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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Move the management of the client connection cache to the I/O thread rather
than managing it from the namespace as an aggregate across all the local
endpoints within the namespace.
This will allow a load of locking to be got rid of in a future patch as
only the I/O thread will be looking at the this.
The downside is that the total number of cached connections on the system
can get higher because the limit is now per-local rather than per-netns.
We can, however, keep the number of client conns in use across the entire
netfs and use that to reduce the expiration time of idle connection.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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Offload the completion of the challenge/response cycle on a service
connection to the I/O thread. After the RESPONSE packet has been
successfully decrypted and verified by the work queue, offloading the
changing of the call states to the I/O thread makes iteration over the
conn's channel list simpler.
Do this by marking the RESPONSE skbuff and putting it onto the receive
queue for the I/O thread to collect. We put it on the front of the queue
as we've already received the packet for it.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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Tidy up the abort generation infrastructure in the following ways:
(1) Create an enum and string mapping table to list the reasons an abort
might be generated in tracing.
(2) Replace the 3-char string with the values from (1) in the places that
use that to log the abort source. This gets rid of a memcpy() in the
tracepoint.
(3) Subsume the rxrpc_rx_eproto tracepoint with the rxrpc_abort tracepoint
and use values from (1) to indicate the trace reason.
(4) Always make a call to an abort function at the point of the abort
rather than stashing the values into variables and using goto to get
to a place where it reported. The C optimiser will collapse the calls
together as appropriate. The abort functions return a value that can
be returned directly if appropriate.
Note that this extends into afs also at the points where that generates an
abort. To aid with this, the afs sources need to #define
RXRPC_TRACE_ONLY_DEFINE_ENUMS before including the rxrpc tracing header
because they don't have access to the rxrpc internal structures that some
of the tracepoints make use of.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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Provide a means by which an event notification can be sent to a connection
through such that the I/O thread can pick it up and handle it rather than
doing it in a separate workqueue.
This is then used to move the deferred final ACK of a call into the I/O
thread rather than a separate work queue as part of the drive to do all
transmission from the I/O thread.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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Call the rxrpc_conn_retransmit_call() directly from rxrpc_input_packet()
rather than calling it via connection event handling.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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Dan Carpenter sayeth[1]:
The patch 5e6ef4f1017c: "rxrpc: Make the I/O thread take over the
call and local processor work" from Jan 23, 2020, leads to the
following Smatch static checker warning:
net/rxrpc/io_thread.c:283 rxrpc_input_packet()
warn: bool is not less than zero.
Fix this (for now) by changing rxrpc_new_incoming_call() to return an int
with 0 or error code rather than bool. Note that the actual return value
of rxrpc_input_packet() is currently ignored. I have a separate patch to
clean that up.
Fixes: 5e6ef4f1017c ("rxrpc: Make the I/O thread take over the call and local processor work")
Reported-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Link: http://lists.infradead.org/pipermail/linux-afs/2022-December/006123.html [1]
Signed-off-by: David S. Miller <davem@davemloft.net>
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The rxrpc I/O thread checks to see if there's any work it needs to do, and
if not, checks kthread_should_stop() before scheduling, and if it should
stop, breaks out of the loop and tries to clean up and exit.
This can, however, race with socket destruction, wherein outstanding calls
are aborted and released from the socket and then the socket unuses the
local endpoint, causing kthread_stop() to be issued. The abort is deferred
to the I/O thread and the event can by issued between the I/O thread
checking if there's any work to be done (such as processing call aborts)
and the stop being seen.
This results in the I/O thread stopping processing of events whilst call
cleanup events are still outstanding, leading to connections or other
objects still being around and uncleaned up, which can result in assertions
being triggered, e.g.:
rxrpc: AF_RXRPC: Leaked client conn 00000000e8009865 {2}
------------[ cut here ]------------
kernel BUG at net/rxrpc/conn_client.c:64!
Fix this by retrieving the kthread_should_stop() indication, then checking
to see if there's more work to do, and going back round the loop if there
is, and breaking out of the loop only if there wasn't.
This was triggered by a syzbot test that produced some other symptom[1].
Fixes: a275da62e8c1 ("rxrpc: Create a per-local endpoint receive queue and I/O thread")
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Link: https://lore.kernel.org/r/0000000000002b4a9f05ef2b616f@google.com/ [1]
Signed-off-by: David S. Miller <davem@davemloft.net>
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When starting a kthread, the __kthread_create_on_node() function, as called
from kthread_run(), waits for a completion to indicate that the task_struct
(or failure state) of the new kernel thread is available before continuing.
This does not wait, however, for the thread function to be invoked and,
indeed, will skip it if kthread_stop() gets called before it gets there.
If this happens, though, kthread_run() will have returned successfully,
indicating that the thread was started and returning the task_struct
pointer. The actual error indication is returned by kthread_stop().
Note that this is ambiguous, as the caller cannot tell whether the -EINTR
error code came from kthread() or from the thread function.
This was encountered in the new rxrpc I/O thread, where if the system is
being pounded hard by, say, syzbot, the check of KTHREAD_SHOULD_STOP can be
delayed long enough for kthread_stop() to get called when rxrpc releases a
socket - and this causes an oops because the I/O thread function doesn't
get started and thus doesn't remove the rxrpc_local struct from the
local_endpoints list.
Fix this by using a completion to wait for the thread to actually enter
rxrpc_io_thread(). This makes sure the thread can't be prematurely
stopped and makes sure the relied-upon cleanup is done.
Fixes: a275da62e8c1 ("rxrpc: Create a per-local endpoint receive queue and I/O thread")
Reported-by: syzbot+3538a6a72efa8b059c38@syzkaller.appspotmail.com
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: Hillf Danton <hdanton@sina.com>
Link: https://lore.kernel.org/r/000000000000229f1505ef2b6159@google.com/
Signed-off-by: David S. Miller <davem@davemloft.net>
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For ACKs generated inside the I/O thread, transmit the ACK at the point of
generation. Where the ACK is generated outside of the I/O thread, it's
offloaded to the I/O thread to transmit it.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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Move the functions from the call->processor and local->processor work items
into the domain of the I/O thread.
The call event processor, now called from the I/O thread, then takes over
the job of cranking the call state machine, processing incoming packets and
transmitting DATA, ACK and ABORT packets. In a future patch,
rxrpc_send_ACK() will transmit the ACK on the spot rather than queuing it
for later transmission.
The call event processor becomes purely received-skb driven. It only
transmits things in response to events. We use "pokes" to queue a dummy
skb to make it do things like start/resume transmitting data. Timer expiry
also results in pokes.
The connection event processor, becomes similar, though crypto events, such
as dealing with CHALLENGE and RESPONSE packets is offloaded to a work item
to avoid doing crypto in the I/O thread.
The local event processor is removed and VERSION response packets are
generated directly from the packet parser. Similarly, ABORTs generated in
response to protocol errors will be transmitted immediately rather than
being pushed onto a queue for later transmission.
Changes:
========
ver #2)
- Fix a couple of introduced lock context imbalances.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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Extract the peer address from an incoming packet earlier, at the beginning
of rxrpc_input_packet() and thence pass a pointer to it to various
functions that use it as part of the lookup rather than doing it on several
separate paths.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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Shrink the region of rxrpc_input_packet() that is covered by the RCU read
lock so that it only covers the connection and call lookup. This means
that the bits now outside of that can call sleepable functions such as
kmalloc and sendmsg.
Also take a ref on the conn or call we're going to use before we drop the
RCU read lock.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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A received skbuff needs a ref when it gets put on a call data queue or conn
packet queue, and rxrpc_input_packet() and co. jump through a lot of hoops
to avoid double-dropping the skbuff ref so that we can avoid getting a ref
when we queue the packet.
Change this so that the skbuff ref is unconditionally dropped by the caller
of rxrpc_input_packet(). An additional ref is then taken on the packet if
it is pushed onto a queue.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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Copy client call parameters into rxrpc_call earlier so that that can be
used to convey them to the connection code - which can then be offloaded to
the I/O thread.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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Provide a means by which an event notification can be sent to a call such
that the I/O thread can process it rather than it being done in a separate
workqueue. This will allow a lot of locking to be removed.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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Move the processing of error packets into the local endpoint I/O thread,
leaving the handover from UDP to merely transfer them into the local
endpoint queue.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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Split the packet input handler to make the softirq side just dump the
received packet into the local endpoint receive queue and then call the
remainder of the input function from the I/O thread.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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Create a per-local receive queue to which, in a future patch, all incoming
packets will be directed and an I/O thread that will process those packets
and perform all transmission of packets.
Destruction of the local endpoint is also moved from the local processor
work item (which will be absorbed) to the thread.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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Split the code that handles packet reception in softirq mode as a prelude
to moving all the packet processing beyond routing to the appropriate call
and setting up of a new call out into process context.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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