From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755434Ab0C2LEb (ORCPT ); Mon, 29 Mar 2010 07:04:31 -0400 Received: from moutng.kundenserver.de ([212.227.17.9]:61703 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755299Ab0C2LEa (ORCPT ); Mon, 29 Mar 2010 07:04:30 -0400 From: Arnd Bergmann To: Frederic Weisbecker Subject: Re: [GIT, RFC] Killing the Big Kernel Lock Date: Mon, 29 Mar 2010 12:04:24 +0100 User-Agent: KMail/1.12.2 (Linux/2.6.31-19-generic; KDE/4.3.2; x86_64; ; ) Cc: linux-kernel@vger.kernel.org, Matthew Wilcox , Thomas Gleixner , jblunck@suse.de, Alan Cox , Ingo Molnar References: <201003242240.54907.arnd@arndb.de> <20100328231847.GH5116@nowhere> <20100328233847.GJ5116@nowhere> In-Reply-To: <20100328233847.GJ5116@nowhere> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201003291304.24629.arnd@arndb.de> X-Provags-ID: V01U2FsdGVkX18acnnLQRYBFZVtyfx73pKITovyfuafBsF7nVH sYA5i7s4ciru5nq3JmVevFSyeA6nYy4E+ngVv+Bxq1ah/nBgnW ZjyweXPK+izIXZMNU63Bw== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Monday 29 March 2010, Frederic Weisbecker wrote: > On Mon, Mar 29, 2010 at 01:18:48AM +0200, Frederic Weisbecker wrote: > > @@ -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(). The default is default_llseek, which uses the BKL and cannot be used if procfs is builtin and the BKL is a module. > 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. The BKL in procfs is only for proc files that have registered their own .ioctl instead of .unlocked_ioctl method. Converting every file_operations instance to provide an unlocked_ioctl (as one of the other patches does) makes sure that this path is never taken. BTW, there are less than a handful of procfs files that provide an ioctl operation, and those probably should never have been merged. Arnd