From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Matthew Wilcox <matthew@wil.cx>, Brian King <brking@us.ibm.com>,
linux-pci@atrey.karlin.mff.cuni.cz, linux-pm@lists.osdl.org,
linux-kernel@vger.kernel.org, Adam Belay <abelay@MIT.EDU>
Subject: Re: [linux-pm] [PATCH] Block on access to temporarily unavailable pci device
Date: Wed, 18 Oct 2006 17:05:02 +0100 [thread overview]
Message-ID: <1161187503.9363.75.camel@localhost.localdomain> (raw)
In-Reply-To: <Pine.LNX.4.44L0.0610181151450.6766-100000@iolanthe.rowland.org>
Ar Mer, 2006-10-18 am 11:52 -0400, ysgrifennodd Alan Stern:
> Don't you want the user process to wait in TASK_INTERRUPTIBLE? It would
> require only a very simple change.
That just makes the problem even worse, to go with the kernel driver
"what the hell do do if.." we get a user space one thats based around
incompatibility with the existing behaviour.
There are much saner ways to sort that out without breaking the API
If its going to be a bounded short wait -> pause
If its might be a long wait -> cached
If its gone for good then error
If the user specified O_NDELAY then -EWOULDBLOCK not wait
That way you don't break anything and you get sensible Unix semantics.
The wait queue Matthew added also means select() can be fitted up to do
the right thing for the O_NDELAY case.
Alan
next prev parent reply other threads:[~2006-10-18 16:04 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-10-17 14:51 [PATCH] Block on access to temporarily unavailable pci device Matthew Wilcox
2006-10-17 14:54 ` Matthew Wilcox
2006-10-17 21:25 ` Brian King
2006-10-18 14:38 ` [linux-pm] " Alan Stern
2006-10-18 14:51 ` Matthew Wilcox
2006-10-18 15:52 ` Alan Stern
2006-10-18 16:05 ` Alan Cox [this message]
2006-10-18 16:09 ` Matthew Wilcox
2006-10-18 16:42 ` Alan Cox
2006-10-18 14:51 ` Matthew Wilcox
2006-10-18 14:57 ` Matthew Wilcox
2006-10-18 15:12 ` Nick Piggin
2006-10-18 15:16 ` Matthew Wilcox
2006-10-18 15:27 ` Nick Piggin
2006-10-18 15:50 ` Alan Cox
2006-10-18 16:20 ` Matthew Wilcox
2006-10-18 16:39 ` Alan Cox
2006-10-18 17:14 ` Matthew Wilcox
2006-10-19 15:41 ` [PATCH] Block on access to temporarily unavailable pci device [version 3] Matthew Wilcox
2006-10-19 16:32 ` Alan Cox
2006-10-19 23:13 ` Adam Belay
2006-10-19 23:51 ` Greg KH
2006-10-20 21:50 ` Brian King
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