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Date: Mon, 29 Mar 2010 01:38:48 +0200
From: Frederic Weisbecker <fweisbec@gmail.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: linux-kernel@vger.kernel.org, Matthew Wilcox <matthew@wil.cx>,
       Thomas Gleixner <tglx@linutronix.de>, jblunck@suse.de,
       Alan Cox <alan@linux.intel.com>, Ingo Molnar <mingo@elte.hu>
Subject: Re: [GIT, RFC] Killing the Big Kernel Lock
Message-ID: <20100328233847.GJ5116@nowhere>
References: <201003242240.54907.arnd@arndb.de> <20100328231847.GH5116@nowhere>
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On Mon, Mar 29, 2010 at 01:18:48AM +0200, Frederic Weisbecker wrote:
> On Wed, Mar 24, 2010 at 10:40:54PM +0100, Arnd Bergmann wrote:
> > Arnd Bergmann (44):
> >       [...]
> >       procfs: kill BKL in llseek
> 
> 
> About this one, there is a "sensible" part:
> 
> 
> @@ -1943,7 +1949,7 @@ static ssize_t proc_fdinfo_read(struct file *file, char __user *buf,
>  }
>  
>  static const struct file_operations proc_fdinfo_file_operations = {
> -	.open		= nonseekable_open,
> +	.llseek		= generic_file_llseek,
>  	.read		= proc_fdinfo_read,
>  };
>  
> 
> Replacing default_llseek() by generic_file_llseek() as you
> did for most of the other parts is fine.
> 
> But the above changes the semantics as it makes it seekable.
> Why not just keeping it as is? It just ends up in no_llseek().
> 


There is also the ioctl part that takes the bkl in procfs.
I'll just check nothing weird happens there wrt file pos.
We probably first need to pushdown the bkl in the procfs
ioctl handlers.