Subject: Re: modules registering as sysctl handlers
From: Rusty Russell <rusty@rustcorp.com.au>
To: viro@parcelfarce.linux.theplanet.co.uk
Cc: Muli Ben-Yehuda <mulix@mulix.org>,
       Linux-Kernel <linux-kernel@vger.kernel.org>
In-Reply-To: <20040302124106.GQ16357@parcelfarce.linux.theplanet.co.uk>
References: <20040302122909.GG24260@mulix.org>
	 <20040302124106.GQ16357@parcelfarce.linux.theplanet.co.uk>
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Date: Wed, 03 Mar 2004 11:05:39 +1100
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On Tue, 2004-03-02 at 23:41, viro@parcelfarce.linux.theplanet.co.uk
wrote:
> 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.

Al is referring to the fact that there's no protection for a dynamically
allocated ctl_table.

However, an owner field and standard module_get() would solve the case
of statically declared ctl_table.

I don't know that there's a current user who requires it though?

Rusty.
-- 
Anyone who quotes me in their signature is an idiot -- Rusty Russell

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