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Date: Fri, 2 Mar 2007 11:45:24 -0800
From: Andrew Morton <akpm@linux-foundation.org>
To: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>,
       Martin Schwidefsky <schwidefsky@de.ibm.com>,
       john stultz <johnstul@us.ibm.com>, Roman Zippel <zippel@linux-m68k.org>,
       Christian Borntraeger <cborntra@de.ibm.com>, linux-s390@vger.kernel.org,
       linux-kernel@vger.kernel.org
Subject: Re: [patch] timer/hrtimer: take per cpu locks in sane order
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On Fri, 2 Mar 2007 20:08:36 +0100
Heiko Carstens <heiko.carstens@de.ibm.com> wrote:

> +/*
> + * double_hrtimer_lock/unlock are used to ensure that on cpu hotplug the
> + * per cpu timer locks are always taken in the same order.
> + */
> +static void double_hrtimer_lock(struct hrtimer_cpu_base *base1,
> +				struct hrtimer_cpu_base *base2, int ind)
> +	__acquires(base1->lock)
> +	__acquires(base2->lock)
> +{
>
> ...
>
> +/*
> + * double_timer_lock/unlock are used to ensure that on cpu hotplug the
> + * per cpu timer locks are always taken in the same order.
> + */
> +static void __devinit double_timer_lock(tvec_base_t *base1,
> +					tvec_base_t *base2, int ind)
> +	__acquires(base1->lock)
> +	__acquires(base2->lock)

hm.  Can we not just pass in the spinlock_t*'s and use a common function?

	void double_spin_lock(spinlock_t *l1, spinlock_t *l2, int ind);

that way it has nothing to do with timers and can potentially be used
elsewhere in the kernel, too.

(what does "ind" mean?)