rxrpc: Only disconnect calls in the I/O thread

jira LE-1907
Rebuild_History Non-Buildable kernel-rt-5.14.0-284.30.1.rt14.315.el9_2
commit-author David Howells <dhowells@redhat.com>
commit 03fc55a
Empty-Commit: Cherry-Pick Conflicts during history rebuild.
Will be included in final tarball splat. Ref for failed cherry-pick at:
ciq/ciq_backports/kernel-rt-5.14.0-284.30.1.rt14.315.el9_2/03fc55ad.failed

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: cf37b59 ("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
(cherry picked from commit 03fc55a)
	Signed-off-by: Jonathan Maple <jmaple@ciq.com>

# Conflicts:
#	include/trace/events/rxrpc.h
#	net/rxrpc/call_event.c
#	net/rxrpc/call_object.c
#	net/rxrpc/input.c
#	net/rxrpc/recvmsg.c

Author: PlaidCat