linux-kernel - Re: [RFC][PATCH 2/6] x86, nmi: create new NMI handler routines

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Date:	Mon, 22 Aug 2011 16:16:20 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Don Zickus <dzickus@...hat.com>
Cc:	x86@...nel.org, Andi Kleen <andi@...stfloor.org>,
	Robert Richter <robert.richter@....com>, ying.huang@...el.com,
	LKML <linux-kernel@...r.kernel.org>, jason.wessel@...driver.com
Subject: Re: [RFC][PATCH 2/6] x86, nmi: create new NMI handler routines

On Fri, 2011-08-19 at 16:37 -0400, Don Zickus wrote:
> +static struct nmiaction *__free_nmi(unsigned int type, const char *name)
> +{
> +       struct nmi_desc *desc = nmi_to_desc(type);
> +       struct nmiaction *n, **np = &(desc->head);
> +       unsigned long flags;
> +
> +       spin_lock_irqsave(&desc->lock, flags);
> +
...
> +
> +       spin_unlock_irqrestore(&desc->lock, flags);
> +       synchronize_rcu();
> +       return *np;
> +}

> +void unregister_nmi_handler(unsigned int type, const char *name)
> +{
> +       kfree(__free_nmi(type, name));
> +}

This code is weird.. why not have the kfree() in __free_nmi(), also why
use sync_rcu() and not use kfree_rcu()?

> +EXPORT_SYMBOL_GPL(unregister_nmi_handler); 

*g*, so binary modules can register an NMI handler, but can't unregister
it..?
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