Date: Tue, 2 Mar 2004 12:41:06 +0000
From: viro@parcelfarce.linux.theplanet.co.uk
To: Muli Ben-Yehuda <mulix@mulix.org>
Cc: Linux-Kernel <linux-kernel@vger.kernel.org>
Subject: Re: modules registering as sysctl handlers
Message-ID: <20040302124106.GQ16357@parcelfarce.linux.theplanet.co.uk>
References: <20040302122909.GG24260@mulix.org>
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On Tue, Mar 02, 2004 at 02:29:09PM +0200, Muli Ben-Yehuda wrote:
> Hi 
> 
> Looking at 2.6.3-bk, it appears that the sysctl code does not raise a
> module's reference count before calling a sysctl handler registered by
> that module. 
> 
> - are modules allowed to register sysctl handlers?
> register_sysctl_table is exported, so I imagine so. 
> 
> - am I missing something and modules are in fact protected against
> concurrent unloading and invocation of sysctl?

They are not and no, bumping refcount would not be anywhere near enough.
It's not just modules - no module refcount will help e.g. per-interface
sysctls.  All dynamic sysctls are b0rken and the best course of action
is to avoid using that crap.

We'll need to fix that mess, but it won't be easy.
-
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