From: Jarek Poplawski <jarkao2@o2.pl>
To: Nadia Derbey <Nadia.Derbey@bull.net>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Alexey Dobriyan <adobriyan@sw.ru>,
linux-kernel@vger.kernel.org
Subject: Re: 2.6.23-rc6-mm1: IPC: sleeping function called ...
Date: Thu, 20 Sep 2007 10:21:05 +0200 [thread overview]
Message-ID: <20070920082105.GB2065@ff.dom.local> (raw)
In-Reply-To: <20070920072821.GA2065@ff.dom.local>
On Thu, Sep 20, 2007 at 09:28:21AM +0200, Jarek Poplawski wrote:
> On Thu, Sep 20, 2007 at 08:24:58AM +0200, Nadia Derbey wrote:
...
> > Before Calling msg_unlock() they call ipc_rcu_getref() that increments a
> > refcount in the rcu header for the msg structure. This guarantees that
> > the the structure won't be freed before they relock it. Once the
> > structure is relocked by ipc_lock_by_ptr(), they do the symmetric
> > operation i.e. ipc_rcu_putref().
...
> which seems to suggest "out" is an RCU protected pointer, so, I
> thought these refcounts were for something else. But, after looking
> at how it's used it turns out to be ~90% wrong: probably 9 out of 10
> places use refcouning around this, so, these rcu_read_locks() don't
> work here at all. So, probably I miss something again, but IMHO,
> these rcu_read_locks/unlocks could be removed here or in
...
...So I missed it again: after all this RCU protection works before
and after refcounting.
Sorry,
Jarek P.
next prev parent reply other threads:[~2007-09-20 8:19 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-09-18 9:17 2.6.23-rc6-mm1: IPC: sleeping function called Alexey Dobriyan
2007-09-18 9:42 ` Andrew Morton
2007-09-18 10:17 ` Andrew Morton
2007-09-18 10:30 ` Nadia Derbey
2007-09-18 10:34 ` Andrew Morton
[not found] ` <20070918142451.418b3b51@twins>
2007-09-18 16:13 ` Paul E. McKenney
2007-09-18 16:57 ` Andrew Morton
2007-09-18 18:29 ` Paul E. McKenney
2007-09-18 19:41 ` Peter Zijlstra
2007-09-18 20:26 ` [PATCH 1/2] lockdep: annotate rcu_read_lock() Peter Zijlstra
2007-09-18 20:27 ` [RFC][PATCH 2/2] lockdep: rcu_dereference() vs rcu_read_lock() Peter Zijlstra
2007-09-18 21:21 ` Paul E. McKenney
2007-09-18 10:27 ` 2.6.23-rc6-mm1: IPC: sleeping function called Andrew Morton
2007-09-18 10:32 ` Alexey Dobriyan
2007-09-18 14:55 ` Nadia Derbey
2007-09-18 17:01 ` Andrew Morton
2007-09-21 9:18 ` Nadia Derbey
2007-09-19 14:07 ` Jarek Poplawski
2007-09-20 6:24 ` Nadia Derbey
2007-09-20 7:28 ` Jarek Poplawski
2007-09-20 8:21 ` Jarek Poplawski [this message]
2007-09-20 8:52 ` Nadia Derbey
2007-09-20 13:08 ` Nadia Derbey
2007-09-20 13:26 ` Jarek Poplawski
2007-09-21 8:44 ` Jarek Poplawski
2007-09-21 10:11 ` Nadia Derbey
2007-09-21 11:03 ` Jarek Poplawski
2007-09-21 11:15 ` Jarek Poplawski
2007-09-24 6:54 ` Jarek Poplawski
2007-09-24 7:43 ` Jarek Poplawski
2007-09-24 8:18 ` Nadia Derbey
2007-09-24 9:50 ` Nadia Derbey
2007-09-25 11:47 ` Jarek Poplawski
2007-09-26 6:13 ` Jarek Poplawski
2007-09-20 13:19 ` Jarek Poplawski
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