linux-kernel - Re: [rtc-linux] [PATCH] rtc: remove BKL for ioctl()

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Message-ID: <20080625105717.2d9f30b2@i1501.lan.towertech.it>
Date:	Wed, 25 Jun 2008 10:57:17 +0200
From:	Alessandro Zummo <alessandro.zummo@...ertech.it>
To:	rtc-linux@...glegroups.com
Cc:	david-b@...bell.net, lkml <linux-kernel@...r.kernel.org>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Jonathan Corbet <corbet@....net>, akpm@...ux-foundation.org
Subject: Re: [rtc-linux] [PATCH] rtc: remove BKL for ioctl()

On Sun, 22 Jun 2008 19:55:42 -0700
David Brownell <david-b@...bell.net> wrote:

> Remove implicit use of BKL in ioctl() from the RTC framework.
> 
> Instead, the rtc->ops_lock is used.  That's the same lock that already
> protects the RTC operations when they're issued through the exported
> rtc_*() calls in drivers/rtc/interface.c ... making this a bugfix, not
> just a cleanup, since both ioctl calls and set_alarm() need to update
> IRQ enable flags and that implies a common lock (which RTC drivers as
> a rule do not provide on their own).
> 
> A new comment at the declaration of "struct rtc_class_ops" summarizes
> current locking rules.  It's not clear to me that the exceptions listed
> there should exist ... if not, those are pre-existing problems which can
> be fixed in a patch that doesn't relate to BKL removal.
> 
> Signed-off-by: David Brownell <dbrownell@...rs.sourceforge.net>


 Acked-by: Alessandro Zummo <a.zummo@...ertech.it>

-- 

 Best regards,

 Alessandro Zummo,
  Tower Technologies - Torino, Italy

  http://www.towertech.it

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