From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932276AbWGLAA5 (ORCPT ); Tue, 11 Jul 2006 20:00:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932280AbWGLAA5 (ORCPT ); Tue, 11 Jul 2006 20:00:57 -0400 Received: from ug-out-1314.google.com ([66.249.92.174]:24555 "EHLO ug-out-1314.google.com") by vger.kernel.org with ESMTP id S932276AbWGLAA5 (ORCPT ); Tue, 11 Jul 2006 20:00:57 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=nM3zIuHaELJy/dKEaFxlTR/yd/fIY50hHojkiQllv8pWqddk7fygCcK6k2e5Mz/Oh9pK6x/atoidneJzLpNLMOqK1hhznWwJgBgYDc13+BumzLJVFVPrcPZ2HFyEVFyQCB+WwJi1HiJvEYEDt2FY/S8y2XjNR1bxPKBb/LodCns= Message-ID: <9e4733910607111700p53697fc8x3f22c720ef0ea29a@mail.gmail.com> Date: Tue, 11 Jul 2006 20:00:55 -0400 From: "Jon Smirl" To: "Paul Fulghum" Subject: Re: tty's use of file_list_lock and file_move Cc: "Alan Cox" , "Theodore Tso" , lkml In-Reply-To: <44B43409.2020401@microgate.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <9e4733910607100810r6e02f69g9a3f6d3d1400b397@mail.gmail.com> <9e4733910607101535i7f395686p7450dc524d9b82ae@mail.gmail.com> <1152573312.27368.212.camel@localhost.localdomain> <9e4733910607101604j16c54ef0r966f72f3501cfd2b@mail.gmail.com> <9e4733910607101649m21579ae2p9372cced67283615@mail.gmail.com> <20060711012904.GD30332@thunk.org> <20060711194456.GA3677@flint.arm.linux.org.uk> <9e4733910607111508x526ee642p5b587698306b22d3@mail.gmail.com> <1152657465.18028.72.camel@localhost.localdomain> <44B43409.2020401@microgate.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On 7/11/06, Paul Fulghum wrote: > Alan Cox wrote: > > Ar Maw, 2006-07-11 am 18:08 -0400, ysgrifennodd Jon Smirl: > > > >>What about adjusting things so the BKL isn't required? I tried > >>completely removing it and died in release_dev. tty_mutex is already > >>locks a lot of stuff, maybe it can be adjusted to allow removal of the > >>BKL. > > > > > > Thats what is happening currently. However it is being done piece by > > piece, slowly and carefully. > > I hate to chime in since I don't have time in the near term > to contribute to the subject, but I do like the idea of removing > the BKL dependence as a first step. I find its semantics akward to keep > track of, and error prone. More explicit locking, even global, would clear things > up for a later push to finer grained (per tty?) locking (where appropriate). > > Making the necessary changes to all the individual drivers, > as Russel's comment about explicitly dropping the new lock when > sleeping pointed out, would be a time consuming (and probably > tedious) task. I'm still looking at doing work in the tty layer but it is turning out to be more complex that I initially thought. I may give removing the BLK another attempt when I understand things better. I have all of the lock debugging turned on in my kernel. I did get nice messages when I did dumb things like sleeping with locks held or deadlocking that led to quickly fixing the code. Much better than the old system of freezing the box up. -- Jon Smirl jonsmirl@gmail.com