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From: Andy Lutomirski <luto@amacapital.net>
Date: Wed, 29 Apr 2015 12:42:02 -0700
Message-ID: <CALCETrVz8-24U5iBdX4P3hrGLXvpiX72o=pw6uW2yGzMmGy+ow@mail.gmail.com>
Subject: Re: [GIT PULL] kdbus for 4.1-rc1
To: Austin S Hemmelgarn <ahferroin7@gmail.com>
Cc: Harald Hoyer <harald@redhat.com>, Arnd Bergmann <arnd@arndb.de>,
        Havoc Pennington <hp@pobox.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Jiri Kosina <jkosina@suse.cz>,
        Andrew Morton <akpm@linux-foundation.org>,
        Daniel Mack <daniel@zonque.org>,
        One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Lukasz Skalski <l.skalski@samsung.com>,
        "Theodore Ts'o" <tytso@mit.edu>, Tom Gundersen <teg@jklm.no>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        David Herrmann <dh.herrmann@gmail.com>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        John Stoffel <john@stoffel.org>, Djalal Harouni <tixxdz@opendz.org>
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On Wed, Apr 29, 2015 at 12:30 PM, Austin S Hemmelgarn
<ahferroin7@gmail.com> wrote:
> On 2015-04-29 14:54, Andy Lutomirski wrote:
>>
>> On Apr 29, 2015 5:48 AM, "Harald Hoyer" <harald@redhat.com> wrote:
>>>
>>>
>>>   * Being in the kernel closes a lot of races which can't be fixed with
>>>     the current userspace solutions.  For example, with kdbus, there is a
>>>     way a client can disconnect from a bus, but do so only if no further
>>>     messages present in its queue, which is crucial for implementing
>>>     race-free "exit-on-idle" services
>>
>>
>> This can be implemented in userspace.
>>
>> Client to dbus daemon: may I exit now?
>> Dbus daemon to client: yes (and no more messages) or no
>>
> Depending on how this is implemented, there would be a potential issue if a
> message arrived for the client after the daemon told it it could exit, but
> before it finished shutdown, in which case the message might get lost.
>

Then implement it the right way?  The client sends some kind of
sequence number with its request.

--Andy
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