Re: [PATCH] Allow raw_notifier callouts to unregister themselves

From: Alan Stern
Date: Tue May 16 2006 - 11:40:44 EST

On Thu, 11 May 2006, David S. Miller wrote:

> From: Andrew Morton <akpm@xxxxxxxx>
> Date: Thu, 11 May 2006 11:25:09 -0700
> > Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote:
> > >
> > > Since raw_notifier chains don't benefit from any centralized locking
> > > protections, they shouldn't suffer from the associated limitations.
> > > Under some circumstances it might make sense for a raw_notifier callout
> > > routine to unregister itself from the notifier chain. This patch (as678)
> > > changes the notifier core to allow for such things.
> >
> > ok... Can you see any reason why 2.6.17 needs this?
> If this patch makes raw notifiers behave more closely to the
> way notifiers did before the notifier patch went into 2.6.17,
> we should seriouly consider it. We've had enough regressions
> from that patch, and anything which minimizes any possible other
> such regressions would be a plus.

Sorry I'm a little late replying to this...

Actually this patch makes raw notifiers behave a little _less_ like the
original pre-2.6.17 notifiers. With the original code, a notifier callout
routine could unregister itself and deallocate its notifier_block, thereby
causing an oops when it returned. With this patch, the oops will not

That's the only difference.

Alan Stern

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