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From: Oliver Neukum <oliver@neukum.org>
To: Pantelis Koukousoulas <pktoss@gmail.com>
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>
Subject: Re: How to tell whether a struct file is held by a process?
Date: Fri, 22 May 2009 15:38:08 +0200	[thread overview]
Message-ID: <200905221538.09073.oliver@neukum.org> (raw)
In-Reply-To: <1295ed070905220630q67c62569o9753425abf529742@mail.gmail.com>

Am Freitag, 22. Mai 2009 15:30:20 schrieb Pantelis Koukousoulas:
> The only problem I find with leaving mutual exclusion 100% to userspace and
> burdening the kernel only with the decision of whether a port should be
> handled by kernel or userspace is this:
>
> Suppose a device needs a reset as part of its init sequence (a whole lot
> of them do, this is not purely hypothetical). Then a different process may
> get to operate the device before and after the reset and hilarity may
> result from that.

If you leave the locking against user space to user space this can happen
any time, not just due to a reset. What is so special about reset? You just
need a user space locking scheme operating on port numbers, not device
addresses.

	Regards
		Oliver


  reply	other threads:[~2009-05-22 13:37 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-05-19 16:57 Alan Stern
2009-05-21  9:52 ` Al Viro
2009-05-21 14:06   ` Alan Stern
2009-05-21 21:07     ` Kay Sievers
2009-05-21 21:27       ` Alan Stern
2009-05-22 13:30         ` Pantelis Koukousoulas
2009-05-22 13:38           ` Oliver Neukum [this message]
2009-05-22 13:43           ` Alan Cox
2009-05-22 13:52             ` Pantelis Koukousoulas
2009-05-22 14:12               ` Alan Cox
2009-05-22 14:29                 ` Pantelis Koukousoulas
2009-05-21 22:14       ` Alan Cox
2009-05-22  1:28         ` Kyle Moffett
2009-05-22  9:53           ` Alan Cox
2009-05-22 15:12             ` Alan Stern
2009-05-22 15:20               ` Alan Cox
2009-05-22 16:04                 ` Alan Stern
2009-05-22 16:23                   ` Pantelis Koukousoulas
2009-05-22 18:19                     ` Alan Stern
2009-05-22 15:21               ` Kay Sievers
2009-05-22 15:54                 ` Alan Stern
2009-05-22 18:24                   ` Kay Sievers
2009-05-22 18:48                     ` Pantelis Koukousoulas
2009-05-22 19:31                     ` Alan Stern
2009-05-22 21:54                       ` Kay Sievers
2009-05-22 22:07                         ` Alan Stern
2009-05-23 22:47                           ` Kay Sievers
2009-05-22  8:36         ` Oliver Neukum
2009-05-21 22:22     ` Alan Cox
2009-05-22 12:26     ` Oliver Neukum

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