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From: Grant Likely <grant.likely@secretlab.ca>
Date: Wed, 4 May 2011 14:26:56 -0600
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Subject: Re: [PATCH] irq: add irq_alloc_desc_between() helper
To: tglx@linutronix.de, linux-kernel@vger.kernel.org, miltonm@bga.com
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On Wed, May 4, 2011 at 2:19 PM, Grant Likely <grant.likely@secretlab.ca> wrote:
> Written in response to conversation on IRC about needing to specify an upper
> limit on the virq value returned for some MSI interrupt controllers.  Compiled
> only; untested
>
> Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
> ---
>  include/linux/irq.h  |    9 ++++++++-
>  kernel/irq/irqdesc.c |    5 ++++-
>  2 files changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/irq.h b/include/linux/irq.h
> index 09a3080..bcb712b 100644
> --- a/include/linux/irq.h
> +++ b/include/linux/irq.h
> @@ -544,10 +544,17 @@ static inline struct msi_desc *irq_data_get_msi(struct irq_data *d)
>        return d->msi_desc;
>  }
>
> -int irq_alloc_descs(int irq, unsigned int from, unsigned int cnt, int node);
> +int irq_alloc_descs_between(int irq, unsigned int from, unsigned int cnt,
> +                           unsigned int max, int node);
>  void irq_free_descs(unsigned int irq, unsigned int cnt);
>  int irq_reserve_irqs(unsigned int from, unsigned int cnt);
>
> +static inline int irq_alloc_descs(int irq, unsigned int from, unsigned int cnt,
> +                                 int node)
> +{
> +       return irq_alloc_descs_between(irq, from, cnt, 0, node);
> +}
> +
>  static inline int irq_alloc_desc(int node)
>  {
>        return irq_alloc_descs(-1, 0, 1, node);
> diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
> index 2c039c9..c1ddabd 100644
> --- a/kernel/irq/irqdesc.c
> +++ b/kernel/irq/irqdesc.c
> @@ -322,7 +322,7 @@ void irq_free_descs(unsigned int from, unsigned int cnt)
>  * Returns the first irq number or error code
>  */
>  int __ref
> -irq_alloc_descs(int irq, unsigned int from, unsigned int cnt, int node)
> +irq_alloc_descs_between(int irq, unsigned int from, unsigned int cnt, unsigned int max, int node)
>  {
>        int start, ret;
>
> @@ -337,6 +337,9 @@ irq_alloc_descs(int irq, unsigned int from, unsigned int cnt, int node)
>        if (irq >=0 && start != irq)
>                goto err;
>
> +       if (max && start + cnt >= max)

Actually, this should be 'if (max && start + cnt > max)'

g.