linux-kernel - Re: [PATCH 4/6] USB-BKL: Remove BKL use in uhci-debug

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Date:	Thu, 17 Jun 2010 10:43:52 -0700
From:	Greg KH <greg@...ah.com>
To:	Alan Stern <stern@...land.harvard.edu>
Cc:	Arnd Bergmann <arnd@...db.de>, Greg KH <gregkh@...e.de>,
	Kernel development list <linux-kernel@...r.kernel.org>,
	USB list <linux-usb@...r.kernel.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	John Kacur <jkacur@...hat.com>,
	Andi Kleen <andi@...stfloor.org>,
	Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH 4/6] USB-BKL: Remove BKL use in uhci-debug

On Wed, Jun 02, 2010 at 09:47:46AM -0400, Alan Stern wrote:
> On Tue, 1 Jun 2010, Arnd Bergmann wrote:
> 
> > From: Andi Kleen <ak@...ux.intel.com>
> > 
> > BKL was not really needed, just came from earlier push downs.
> 
> Yes.
> 
> > The only part that's a bit dodgy is the lseek function. Would
> > need another lock or atomic access to fpos on 32bit?
> > Better to have a libfs lseek
> 
> It doesn't matter.  Anyone who tries to do lseeks on this file 
> from two different threads, simultaneously, deserves what they get.
> 
> > @@ -539,11 +534,11 @@ static loff_t uhci_debug_lseek(struct file *file, loff_t off, int whence)
> >  		new = file->f_pos + off;
> >  		break;
> >  	}
> > +
> > +	/* XXX: Can size shrink? */
> >  	if (new < 0 || new > up->size) {
> > -		unlock_kernel();
> >  		return -EINVAL;
> >  	}
> > -	unlock_kernel();
> >  	return (file->f_pos = new);
> >  }
> 
> This comment isn't needed; the size cannot change after the file has 
> been opened.

I've removed the comment in the version I just committed.

thanks,

greg k-h
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