linux-kernel - Re: [PATCH 2/8] autofs: Pushdown the bkl from ioctl

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Message-ID: <20100519182234.GB9752@nowhere>
Date:	Wed, 19 May 2010 20:22:36 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Ingo Molnar <mingo@...e.hu>, LKML <linux-kernel@...r.kernel.org>,
	Autofs <autofs@...ux.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	John Kacur <jkacur@...hat.com>, Arnd Bergmann <arnd@...db.de>
Subject: Re: [PATCH 2/8] autofs: Pushdown the bkl from ioctl

On Wed, May 19, 2010 at 11:13:50AM -0700, H. Peter Anvin wrote:
> On 05/19/2010 11:08 AM, Frederic Weisbecker wrote:
> > On Wed, May 19, 2010 at 11:02:04AM -0700, H. Peter Anvin wrote:
> >> On 05/19/2010 10:24 AM, Frederic Weisbecker wrote:
> >>>   * generate kernel reactions
> >>>   */
> >>> -static int autofs_root_ioctl(struct inode *inode, struct file *filp,
> >>> +static int autofs_root_ioctl_unlocked(struct inode *inode, struct file *filp,
> >>>  			     unsigned int cmd, unsigned long arg)
> >>>  {
> >>>  	struct autofs_sb_info *sbi = autofs_sbi(inode->i_sb);
> >>> @@ -579,3 +579,16 @@ static int autofs_root_ioctl(struct inode *inode, struct file *filp,
> >>>  		return -ENOSYS;
> >>>  	}
> >>>  }
> >>> +
> >>> +static long autofs_root_ioctl(struct file *filp,
> >>> +			     unsigned int cmd, unsigned long arg)
> >>> +{
> >>
> >> The choice of naming here seems reverse in my opinion.
> > 
> > 
> > Oh, why?
> > 
> > The function that holds the bkl calls its unlocked version.
> > 
> 
> But it's not ... it is locked at that point.  It's not lock*ing*, but it
> is not *unlocked*, either.  Furthermore, it is directly contradicting
> the naming scheme of the ops structure.


It depends on the point of view. The function itself doesn't lock, it is the
"naked point", so if you take it, you need to lock before, that's what the
name wants to tell.

But may be that's the opposite point of view than the common one, for
which I wouldn't be suprised as my brain tends to be upside down...

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