From: Joe Seigh <jseigh_02@xemaps.com>
To: linux-kernel@vger.kernel.org
Subject: Re: Notifier chains are unsafe
Date: Sat, 29 Oct 2005 08:25:04 -0400 [thread overview]
Message-ID: <djvpme$p83$1@sea.gmane.org> (raw)
In-Reply-To: <E1EUxn7-00081k-00@gondolin.me.apana.org.au>
Herbert Xu wrote:
> Andreas Kleen <ak@suse.de> wrote:
>
>>Am Mi 26.10.2005 02:01 schrieb Chandra Seetharaman
>><sekharan@us.ibm.com>:
>>
>>
>>>>Better would be likely to use RCU.
>>>
>>>RCU will be a problem if the registered notifiers need to block.
>>
>>?
>>Actually blocking should be ok, as long as the blocking notifier doesn't
>>unregister
>>itself. The current next pointer will be always reloaded after the
>>blocking.
>
>
> Blocking would be OK as long as you reference count the objects.
With or without RCU? I.e., it's just a straighforward reference counting
solution and RCU is being used to allow incrementing the reference counts
safely. Otherwise, without RCU you'd need a lock to safely increment the
reference counts. Also note that with reference counting, the deletes of
the objects can occur any time a reference count is decremented. So that
would include the notify_call threads as well.
--
Joe Seigh
next prev parent reply other threads:[~2005-10-29 12:28 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-10-24 20:48 Notifier chains are unsafe Alan Stern
2005-10-25 16:59 ` Joe Seigh
2005-10-25 23:30 ` Chandra Seetharaman
2005-10-26 18:46 ` Alan Stern
2005-10-26 19:05 ` Andreas Kleen
2005-10-26 20:40 ` Alan Stern
2005-10-26 21:44 ` Andi Kleen
2005-10-26 23:20 ` Chandra Seetharaman
2005-10-27 1:17 ` Joe Seigh
2005-10-28 1:36 ` Chandra Seetharaman
2005-10-27 14:13 ` Alan Stern
2005-10-26 22:40 ` Chandra Seetharaman
2005-10-27 15:28 ` Alan Stern
2005-10-27 20:43 ` Chandra Seetharaman
2005-10-27 21:21 ` Alan Stern
2005-10-27 23:02 ` Chandra Seetharaman
2005-10-28 0:48 ` Keith Owens
2005-10-28 1:34 ` Chandra Seetharaman
2005-10-28 14:23 ` Alan Stern
2005-10-28 22:15 ` Chandra Seetharaman
2005-10-29 14:51 ` Alan Stern
2005-10-31 22:22 ` Chandra Seetharaman
2005-11-01 15:24 ` Alan Stern
2005-11-01 20:20 ` Chandra Seetharaman
2005-11-01 21:20 ` Alan Stern
2005-11-02 9:50 ` Keith Owens
2005-11-02 16:03 ` Alan Stern
[not found] ` <mailman.1130460600.30060.linux-kernel2news@redhat.com>
2005-10-28 4:35 ` Pete Zaitcev
2005-10-25 23:43 ` Andi Kleen
2005-10-26 0:01 ` Chandra Seetharaman
2005-10-26 17:11 ` Andreas Kleen
2005-10-27 2:46 ` Herbert Xu
2005-10-29 12:25 ` Joe Seigh [this message]
2005-10-26 6:11 ` Keith Owens
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