connection.c: handle notification on release w/o conn->mutex_lock held

Fixes the following lockdep warning:

[   15.247949] =============================================
[   15.253654] [ INFO: possible recursive locking detected ]
[   15.259366] 3.9.0-rc6-00096-g27e4863 #515 Tainted: G           O
[   15.265713] ---------------------------------------------
[   15.271421] test-kdbus/114 is trying to acquire lock:
[   15.276761]  (&conn->msg_lock/1){+.+.+.}, at: [<bf001efc>] kdbus_conn_enqueue_kmsg+0xcc/0x11c [kdbus]
[   15.286583]
[   15.286583] but task is already holding lock:
[   15.292748]  (&conn->msg_lock/1){+.+.+.}, at: [<bf000520>] kdbus_conn_release+0xa0/0x1e4 [kdbus]
[   15.302075]
[   15.302075] other info that might help us debug this:
[   15.308977]  Possible unsafe locking scenario:
[   15.308977]
[   15.315234]        CPU0
[   15.317816]        ----
[   15.320396]   lock(&conn->msg_lock/1);
[   15.324371]   lock(&conn->msg_lock/1);
[   15.328348]
[   15.328348]  *** DEADLOCK ***
test/kdbus-util.c: fix format string
kdbus_internal.h: use size_t in kdbus_size_{set,get}_user
update TODO
refuse non-aligned buffers
return errors for KDBUS_CMD_NAME_RELEASE failures
TODO: update
test: ad cast
rename KDBUS_CMD_FNAME_POLICY_NONE -> KDBUS_CMD_FNAME_POLICY_OPEN
fix alignment calculation when iterating over data records
message: fix NUL byte check for destination string
more and stricter input validation
names: verify validity of service names where appropriate
kdbus.h: we want the thread comm, too
kdbus.h: add results of today's discussion with Ryan
add and use kdbus_validate_nul()
validate incoming fname string length
message: fix padding check of iterator through msg data blocks

Also, simplify the macro a bit by not requiring a size variable for it.
names: we have ctype in the kernel, so use it.

Also be safe and check for ascii only names (yes, the later check in the
loop also catches this, but this will error out faster with bad data,
premature optimization and all...)

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
message: make sparse happy when we are checking the alignment of userspace buffers