linux-kernel - Re: please revert commit 53f1b1433da7eac2607a4a0898a221a4485fd732 (rtc: push the BKL down into the driver ioctl method)

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Message-ID: <20080725154846.20d2cda8@lxorguk.ukuu.org.uk>
Date:	Fri, 25 Jul 2008 15:48:46 +0100
From:	Alan Cox <alan@...rguk.ukuu.org.uk>
To:	"Jeff Chua" <jeff.chua.linux@...il.com>
Cc:	lkml <linux-kernel@...r.kernel.org>,
	"Linus Torvalds" <torvalds@...ux-foundation.org>
Subject: Re: please revert commit 53f1b1433da7eac2607a4a0898a221a4485fd732
 (rtc: push the BKL down into the driver ioctl method)

On Fri, 25 Jul 2008 22:26:38 +0800
"Jeff Chua" <jeff.chua.linux@...il.com> wrote:

> 53f1b1433da7eac2607a4a0898a221a4485fd732 is first bad commit
> commit 53f1b1433da7eac2607a4a0898a221a4485fd732
> Author: Alan Cox <alan@...rguk.ukuu.org.uk>
> Date:   Wed Jul 23 21:30:32 2008 -0700
> 
>     rtc: push the BKL down into the driver ioctl method
> 
> 
> This commit is breaking vmware-6.0.4. Upon booting linux (guest) on
> vmware, the whole vmware environment crashed

Having reviewed the patch and the trace I believe you need to take this
up with vmware. All the patch does is slightly alter where the locking is
done. I suspect vmware are blindly calling into the rtc_fops ioctl method
directly in which case they just got burned.

One way to check this would be to add a .ioctl method back which was
simply

rtc_test_ioctl(...)
{
	printk("VMWare caught with pants down\n");
}

if it prints that instead of or while crashing you know who is guilty.

Alan
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