linux-kernel - Re: [PATCH] tty add compat

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Message-ID: <463AA2F5.7030307@microgate.com>
Date:	Thu, 03 May 2007 21:05:25 -0600
From:	Paul Fulghum <paulkf@...rogate.com>
To:	Arnd Bergmann <arnd@...db.de>
CC:	Andrew Morton <akpm@...l.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: [PATCH] tty add compat_ioctl

Paul Fulghum wrote:
> Arnd Bergmann wrote:
>> - In your driver you don't get the big kernel lock in the 
>> compat_ioctl function. I assume that this is correct for
>> the particular driver, but it may be nice if you could
>> consequently also add an unlocked_ioctl function that can
>> be used without the BKL for native ioctls. It would be good
>> to hear an opinon on this from someone who has an insight
>> in tty locking issues though, so I'm Cc:ing some people
>> who have touched that recently.
> 
> I don't count on higher level locking for
> synchronization issues specific to the driver.
> 
> I thought the current compat_ioctl() was already
> meant to *not* have the BKL just like unlocked_ioctl.
> My thought was that any driver getting a recent update
> like compat_ioctl() would need to be reviewed for BKL
> safety and take the lock manually if necessary.

Nevermind. I misread what you wrote (I'm tired).
Yes, adding an unlocked_ioctl() makes sense.

--
Paul

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