From: Peter Zijlstra <peterz@infradead.org>
To: Ming Lei <tom.leiming@gmail.com>
Cc: gregkh@suse.de, akpm@linux-foundation.org,
linux-kernel@vger.kernel.org, ostrikov@nvidia.com,
adobriyan@gmail.com, eric.dumazet@gmail.com, mingo@elte.hu,
Oliver Neukum <oneukum@suse.de>
Subject: Re: [PATCH 3/3] kref: Remove the memory barriers
Date: Mon, 12 Dec 2011 09:56:30 +0100 [thread overview]
Message-ID: <1323680190.16764.48.camel@twins> (raw)
In-Reply-To: <CACVXFVMDEeDBkAdv=AkRZuOH1sNdMGjR3PeHYMVLhwR+FB8gOg@mail.gmail.com>
On Mon, 2011-12-12 at 11:48 +0800, Ming Lei wrote:
> > LOCK
> > obj = lookup(); /* lets assume obj != NULL */
> > kref_get(&obj->ref);
> > UNLOCK
> >
> > value = obj->member;
> >
> > kref_put(&obj->ref);
> >
> > Now, under our memory model, the read from obj->member can both happen,
> > or be observed to happen before the increment from kref_get() is
> > processed.
>
> It should be the problem if another CPU observed that write/read obj
> is done before kref_get.
WHY?!?!?!
next prev parent reply other threads:[~2011-12-12 8:57 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-10 10:43 [PATCH 0/3] kref: inline and barriers Peter Zijlstra
2011-12-10 10:43 ` [PATCH 1/3] kref: Inline all functions Peter Zijlstra
2011-12-10 14:32 ` Ming Lei
2011-12-10 14:59 ` Peter Zijlstra
2011-12-12 22:11 ` Greg KH
2011-12-13 9:36 ` Peter Zijlstra
2011-12-13 17:15 ` Greg KH
2011-12-13 18:52 ` Peter Zijlstra
2011-12-13 19:11 ` Greg KH
2011-12-13 19:36 ` Peter Zijlstra
2011-12-10 10:43 ` [PATCH 2/3] kref: Implement kref_put in terms of kref_sub Peter Zijlstra
2011-12-10 10:43 ` [PATCH 3/3] kref: Remove the memory barriers Peter Zijlstra
2011-12-10 14:07 ` Ming Lei
2011-12-10 14:58 ` Peter Zijlstra
2011-12-10 15:57 ` Ming Lei
2011-12-10 19:49 ` Peter Zijlstra
2011-12-11 2:22 ` Ming Lei
2011-12-11 12:47 ` Peter Zijlstra
2011-12-11 12:59 ` Ming Lei
2011-12-11 15:35 ` Peter Zijlstra
2011-12-11 20:42 ` Peter Zijlstra
2011-12-12 3:48 ` Ming Lei
2011-12-12 8:54 ` Peter Zijlstra
2011-12-12 9:57 ` Ming Lei
2011-12-12 10:12 ` Peter Zijlstra
2011-12-12 10:32 ` Ming Lei
2011-12-12 11:05 ` Peter Zijlstra
2011-12-12 11:19 ` Ming Lei
2011-12-12 11:13 ` Eric Dumazet
2011-12-12 11:15 ` Oliver Neukum
2011-12-12 10:20 ` Oliver Neukum
2011-12-12 19:30 ` Greg KH
2011-12-12 22:56 ` Oliver Neukum
2011-12-12 23:14 ` Greg KH
2011-12-13 11:51 ` Oliver Neukum
2011-12-13 9:12 ` Peter Zijlstra
2011-12-13 9:49 ` Oliver Neukum
2011-12-12 8:55 ` Peter Zijlstra
2011-12-12 15:24 ` Greg KH
2011-12-12 8:56 ` Peter Zijlstra [this message]
2011-12-12 10:10 ` Ming Lei
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