From: Jonathan Corbet <corbet-T1hC0tSOHrs@public.gmane.org>
Cc: Andrew Morton
<akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
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
Subject: Re: [PATCH, RFC] Remove fasync() BKL usage, take 3325
Date: Thu, 22 Jan 2009 22:21:41 -0700 [thread overview]
Message-ID: <20090122222141.4a9501e1@tpl> (raw)
In-Reply-To: <20090122160935.GI15750-qrUzlfsMFqo/4alezvVtWx2eb7JE58TQ@public.gmane.org>
On Thu, 22 Jan 2009 17:09:35 +0100
Andi Kleen <andi-Vw/NltI1exuRpAAqCnN02g@public.gmane.org> 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.
>
> Also it might be that it's even worse than the BKL.
I don't quite see how now. Like the BKL, it's a spinlock.
> It would still require a bitlock because some state in the low
> level fasync needs to be protected.
>
> Oleg has a proposal to do this using a flag bit which seemed
> reasonable to me.
I didn't see a reason to add a one-off custom locking regime for such a
non-hot-path situation. But it would certainly work; if we want to go
that way I'll not fight it.
jon
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WARNING: multiple messages have this Message-ID (diff)
From: Jonathan Corbet <corbet@lwn.net>
To: Andi Kleen <andi@firstfloor.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org, andi@firstfloor.org,
viro@ZenIV.linux.org.uk, oleg@redhat.com,
linux-api@vger.kernel.org, alan@lxorguk.ukuu.org.uk
Subject: Re: [PATCH, RFC] Remove fasync() BKL usage, take 3325
Date: Thu, 22 Jan 2009 22:21:41 -0700 [thread overview]
Message-ID: <20090122222141.4a9501e1@tpl> (raw)
In-Reply-To: <20090122160935.GI15750@one.firstfloor.org>
On Thu, 22 Jan 2009 17:09:35 +0100
Andi Kleen <andi@firstfloor.org> 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.
>
> Also it might be that it's even worse than the BKL.
I don't quite see how now. Like the BKL, it's a spinlock.
> It would still require a bitlock because some state in the low
> level fasync needs to be protected.
>
> Oleg has a proposal to do this using a flag bit which seemed
> reasonable to me.
I didn't see a reason to add a one-off custom locking regime for such a
non-hot-path situation. But it would certainly work; if we want to go
that way I'll not fight it.
jon
next prev parent reply other threads:[~2009-01-23 5:21 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-01-15 22:32 [PATCH, RFC] Remove fasync() BKL usage, take 3325 Jonathan Corbet
2009-01-15 22:32 ` Jonathan Corbet
[not found] ` <20090115153211.663df310-vw3g6Xz/EtPk1uMJSBkQmQ@public.gmane.org>
2009-01-22 14:51 ` Andrew Morton
2009-01-22 14:51 ` Andrew Morton
[not found] ` <20090122065104.2787df2d.akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>
2009-01-22 16:09 ` Andi Kleen
2009-01-22 16:09 ` Andi Kleen
[not found] ` <20090122160935.GI15750-qrUzlfsMFqo/4alezvVtWx2eb7JE58TQ@public.gmane.org>
2009-01-23 5:21 ` Jonathan Corbet [this message]
2009-01-23 5:21 ` Jonathan Corbet
2009-01-22 20:32 ` Christoph Hellwig
2009-01-22 20:32 ` Christoph Hellwig
[not found] ` <20090122203248.GA20159-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2009-01-23 4:56 ` Andi Kleen
2009-01-23 4:56 ` Andi Kleen
[not found] ` <20090123045646.GK15750-qrUzlfsMFqo/4alezvVtWx2eb7JE58TQ@public.gmane.org>
2009-01-28 0:53 ` Andrew Morton
2009-01-28 0:53 ` Andrew Morton
2009-01-28 0:55 ` Andrew Morton
2009-01-28 0:55 ` Andrew Morton
[not found] ` <20090127165504.53ed7a2d.akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>
2009-01-28 3:14 ` Oleg Nesterov
2009-01-28 3:14 ` Oleg Nesterov
[not found] ` <20090128031439.GA11025-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2009-01-28 3:57 ` Jonathan Corbet
2009-01-28 3:57 ` Jonathan Corbet
[not found] ` <20090127205739.1384343f-vw3g6Xz/EtPk1uMJSBkQmQ@public.gmane.org>
2009-01-28 4:23 ` Oleg Nesterov
2009-01-28 4:23 ` Oleg Nesterov
[not found] ` <20090128042337.GA15060-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2009-01-28 14:13 ` Jonathan Corbet
2009-01-28 14:13 ` Jonathan Corbet
2009-01-28 17:36 ` Christoph Hellwig
2009-01-28 17:36 ` Christoph Hellwig
[not found] ` <20090128173618.GA3174-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2009-01-28 17:44 ` Jonathan Corbet
2009-01-28 17:44 ` Jonathan Corbet
[not found] ` <20090128104414.09aee3f9-vw3g6Xz/EtPk1uMJSBkQmQ@public.gmane.org>
2009-01-28 17:55 ` Christoph Hellwig
2009-01-28 17:55 ` Christoph Hellwig
[not found] ` <20090128175541.GA7074-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2009-01-28 18:13 ` Matt Mackall
2009-01-28 18:13 ` Matt Mackall
2009-01-28 21:05 ` Jonathan Corbet
2009-01-28 21:05 ` Jonathan Corbet
2009-01-28 18:14 ` David Daney
2009-01-28 18:14 ` David Daney
2009-01-29 14:37 ` Andi Kleen
2009-01-29 14:37 ` Andi Kleen
2009-01-23 5:15 ` Jonathan Corbet
2009-01-23 5:15 ` Jonathan Corbet
2009-01-23 5:31 ` Andrew Morton
2009-01-23 5:31 ` Andrew Morton
[not found] ` <20090122213105.74142908.akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>
2009-01-23 5:45 ` Matt Mackall
2009-01-23 5:45 ` Matt Mackall
2009-01-23 6:15 ` Andi Kleen
2009-01-23 6:15 ` Andi Kleen
2009-01-23 10:45 ` Bernd Petrovitsch
2009-01-23 5:54 ` Andi Kleen
2009-01-23 5:54 ` Andi Kleen
[not found] ` <20090123055404.GL15750-qrUzlfsMFqo/4alezvVtWx2eb7JE58TQ@public.gmane.org>
2009-01-23 6:01 ` Jonathan Corbet
2009-01-23 6:01 ` Jonathan Corbet
2009-01-23 6:57 ` Andrew Morton
2009-01-23 6:57 ` Andrew Morton
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