From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matt Mackall Subject: Re: [PATCH, RFC] Remove fasync() BKL usage, take 3325 Date: Thu, 22 Jan 2009 23:45:49 -0600 Message-ID: <1232689549.5202.385.camel@calx> References: <20090115153211.663df310@bike.lwn.net> <20090122065104.2787df2d.akpm@linux-foundation.org> <20090122221500.4c62aa54@tpl> <20090122213105.74142908.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20090122213105.74142908.akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org> Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Andrew Morton Cc: Jonathan Corbet , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, andi-Vw/NltI1exuRpAAqCnN02g@public.gmane.org, viro-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org, oleg-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, alan-qBU/x9rampVanCEyBjwyrvXRex20P6io@public.gmane.org List-Id: linux-api@vger.kernel.org On Thu, 2009-01-22 at 21:31 -0800, Andrew Morton wrote: > > On Thu, 22 Jan 2009 22:15:00 -0700 Jonathan Corbet wrote: > > On Thu, 22 Jan 2009 06:51:04 -0800 > > Andrew Morton wrote: > > > > > OK, replacing a lock_kernel() with a spin_lock(&global_lock) is pretty > > > straightforwad. But it's really really sad. It basically leaves a > > > great big FIXME in there. It'd be better to fix it. > > > > > > We don't have a handy lock in struct file which could be borrowed. > > > > Yeah, I noticed that too. > > > > > - We could add one > > > > The problem there is that this bloats struct file, and that seemed like > > something worth avoiding. > > Not a big deal, really. There's one of these for each presently-open file. > It's not like dentries and inodes, which we cache after userspace has > closed off the file handles. I have to agree with Christoph. The priority here is breaking down the BKL and document all the things being protected by it and we've got a reasonably obvious patch in that direction. Meanwhile, there's not currently a pressing demand to make fasync in particular scale that I'm aware of. Having a single big lock here is quite possibly something we'll want to fix down the road, agreed, but until we can actually measure it hurting us, debating about whether to use a bit lock or reuse an existing lock or add a new lock to all struct files is a bit premature. -- http://selenic.com : development and support for Mercurial and Linux -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html