linux-stable.git/net/rxrpc/input.c, branch v6.8

rxrpc: Fix counting of new acks and nacks

2024-02-05T12:34:07+00:00

Fix the counting of new acks and nacks when parsing a packet - something
that is used in congestion control.

As the code stands, it merely notes if there are any nacks whereas what we
really should do is compare the previous SACK table to the new one,
assuming we get two successive ACK packets with nacks in them.  However, we
really don't want to do that if we can avoid it as the tables might not
correspond directly as one may be shifted from the other - something that
will only get harder to deal with once extended ACK tables come into full
use (with a capacity of up to 8192).

Instead, count the number of nacks shifted out of the old SACK, the number
of nacks retained in the portion still active and the number of new acks
and nacks in the new table then calculate what we need.

Note this ends up a bit of an estimate as the Rx protocol allows acks to be
withdrawn by the receiver and packets requested to be retransmitted.

Fixes: d57a3a151660 ("rxrpc: Save last ACK's SACK table rather than marking txbufs")
Signed-off-by: David Howells 
cc: Marc Dionne 
cc: "David S. Miller" 
cc: Eric Dumazet 
cc: Jakub Kicinski 
cc: Paolo Abeni 
cc: linux-afs@lists.infradead.org
cc: netdev@vger.kernel.org
Signed-off-by: David S. Miller

rxrpc: Defer the response to a PING ACK until we've parsed it

2023-11-17T02:50:33+00:00

Defer the generation of a PING RESPONSE ACK in response to a PING ACK until
we've parsed the PING ACK so that we pick up any changes to the packet
queue so that we can update ackinfo.

This is also applied to an ACK generated in response to an ACK with the
REQUEST_ACK flag set.

Note that whilst the problem was added in commit 248f219cb8bc, it didn't
really matter at that point because the ACK was proposed in softirq mode
and generated asynchronously later in process context, taking the latest
values at the time.  But this fix is only needed since the move to parse
incoming packets in an I/O thread rather than in softirq and generate the
ACK at point of proposal (b0346843b1076b34a0278ff601f8f287535cb064).

Fixes: 248f219cb8bc ("rxrpc: Rewrite the data and ack handling code")
Signed-off-by: David Howells 
cc: Marc Dionne 
cc: "David S. Miller" 
cc: Eric Dumazet 
cc: Jakub Kicinski 
cc: Paolo Abeni 
cc: linux-afs@lists.infradead.org
cc: netdev@vger.kernel.org
Signed-off-by: David S. Miller

rxrpc: Fix RTT determination to use any ACK as a source

2023-11-17T02:50:33+00:00

Fix RTT determination to be able to use any type of ACK as the response
from which RTT can be calculated provided its ack.serial is non-zero and
matches the serial number of an outgoing DATA or ACK packet.  This
shouldn't be limited to REQUESTED-type ACKs as these can have other types
substituted for them for things like duplicate or out-of-order packets.

Fixes: 4700c4d80b7b ("rxrpc: Fix loss of RTT samples due to interposed ACK")
Signed-off-by: David Howells 
cc: Marc Dionne 
cc: "David S. Miller" 
cc: Eric Dumazet 
cc: Jakub Kicinski 
cc: Paolo Abeni 
cc: linux-afs@lists.infradead.org
cc: netdev@vger.kernel.org
Signed-off-by: David S. Miller

rxrpc: Fix overproduction of wakeups to recvmsg()

2023-02-20T07:33:25+00:00

Fix three cases of overproduction of wakeups:

 (1) rxrpc_input_split_jumbo() conditionally notifies the app that there's
     data for recvmsg() to collect if it queues some data - and then its
     only caller, rxrpc_input_data(), goes and wakes up recvmsg() anyway.

     Fix the rxrpc_input_data() to only do the wakeup in failure cases.

 (2) If a DATA packet is received for a call by the I/O thread whilst
     recvmsg() is busy draining the call's rx queue in the app thread, the
     call will left on the recvmsg() queue for recvmsg() to pick up, even
     though there isn't any data on it.

     This can cause an unexpected recvmsg() with a 0 return and no MSG_EOR
     set after the reply has been posted to a service call.

     Fix this by discarding pending calls from the recvmsg() queue that
     don't need servicing yet.

 (3) Not-yet-completed calls get requeued after having data read from them,
     even if they have no data to read.

     Fix this by only requeuing them if they have data waiting on them; if
     they don't, the I/O thread will requeue them when data arrives or they
     fail.

Signed-off-by: David Howells 
cc: Marc Dionne 
cc: linux-afs@lists.infradead.org
Link: https://lore.kernel.org/r/3386149.1676497685@warthog.procyon.org.uk
Signed-off-by: Paolo Abeni

rxrpc: Simplify ACK handling

2023-01-31T16:38:35+00:00

Now that general ACK transmission is done from the same thread as incoming
DATA packet wrangling, there's no possibility that the SACK table will be
being updated by the latter whilst the former is trying to copy it to an
ACK.

This means that we can safely rotate the SACK table whilst updating it
without having to take a lock, rather than keeping all the bits inside it
in fixed place and copying and then rotating it in the transmitter.

Therefore, simplify SACK handing by keeping track of starting point in the
ring and rotate slots down as we consume them.

Signed-off-by: David Howells 
cc: Marc Dionne 
cc: linux-afs@lists.infradead.org

rxrpc: De-atomic call->ackr_window and call->ackr_nr_unacked

2023-01-31T16:38:26+00:00

call->ackr_window doesn't need to be atomic as ACK generation and ACK
transmission are now done in the same thread, so drop the atomic64 handling
and split it into two separate members.

Similarly, call->ackr_nr_unacked doesn't need to be atomic now either.

Signed-off-by: David Howells 
cc: Marc Dionne 
cc: linux-afs@lists.infradead.org

rxrpc: Remove call->state_lock

2023-01-06T09:43:33+00:00

All the setters of call->state are now in the I/O thread and thus the state
lock is now unnecessary.

Signed-off-by: David Howells 
cc: Marc Dionne 
cc: linux-afs@lists.infradead.org

rxrpc: Move call state changes from recvmsg to I/O thread

2023-01-06T09:43:33+00:00

Move the call state changes that are made in rxrpc_recvmsg() to the I/O
thread.  This means that, thenceforth, only the I/O thread does this and
the call state lock can be removed.

This requires the Rx phase to be ended when the last packet is received,
not when it is processed.

Since this now changes the rxrpc call state to SUCCEEDED before we've
consumed all the data from it, rxrpc_kernel_check_life() mustn't say the
call is dead until the recvmsg queue is empty (unless the call has failed).

Signed-off-by: David Howells 
cc: Marc Dionne 
cc: linux-afs@lists.infradead.org

rxrpc: Tidy up abort generation infrastructure

2023-01-06T09:43:32+00:00

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 
cc: Marc Dionne 
cc: linux-afs@lists.infradead.org

rxrpc: Only disconnect calls in the I/O thread

2023-01-06T09:43:31+00:00

Only perform call disconnection in the I/O thread to reduce the locking
requirement.

This is the first part of a 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 
cc: Marc Dionne 
cc: linux-afs@lists.infradead.org