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Date: Fri, 22 May 2009 17:29:39 +0300
Message-ID: <1295ed070905220729l4c90e3f4le60743b1ab661ecf@mail.gmail.com>
Subject: Re: How to tell whether a struct file is held by a process?
From: Pantelis Koukousoulas <pktoss@gmail.com>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Kernel development list <linux-kernel@vger.kernel.org>,
       Kay Sievers <kay.sievers@vrfy.org>, Al Viro <viro@zeniv.linux.org.uk>,
       Alan Stern <stern@rowland.harvard.edu>
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>> > Firstly can you explain *why* you think there is a problem ?
>> >
>>
>> I admit this could be a bias from the way I imagined the whole thing
>> to work before
>> this discussion. I think I can see how a userspace locking scheme based on port
>> numbers could avoid also the reset problem
>
> That was a serious request to understand what you think the problem is
> and what problem is worrying you. I'm deeply sceptical of the need for
> any kernel locking on this one but I'd like to understand better why you
> think there are some cases it would be needed.
>

I don't anymore think kernel locking is really needed for this part. I 'm sorry
if my answer did not sound as serious as your request.

So, as long as the kernel has a facility to allow assigning ports to userspace,
the rest can be arranged between the userspace processes in a cooperative
manner (and in fact this seems to be the only sufficiently clean way from what
I can tell).

Thanks,
Pantelis