linux-kernel - Re: [PATCH v3 10/27] genirq: Split __irq_reserve_irqs from irq_alloc

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Date:	Mon, 10 Jun 2013 15:51:56 +0200
From:	Alexander Gordeev <agordeev@...hat.com>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...e.hu>,
	"H. Peter Anvin" <hpa@...or.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>, linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 10/27] genirq: Split __irq_reserve_irqs from
 irq_alloc_descs

On Fri, Jun 07, 2013 at 03:30:56PM -0700, Yinghai Lu wrote:
> irq_alloc_descs and irq_reserve_irqs are almost the same.
> Separate code out to __irq_reserved_irqs, and other two reuse
> __irq_reserve_irqs.
> 
> We will use __irq_reserve_irqs for coming ioapic hotplug support.
> 
> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
> Cc: Alexander Gordeev <agordeev@...hat.com>
> ---
>  include/linux/irq.h  |  1 +
>  kernel/irq/irqdesc.c | 54 ++++++++++++++++++++++++++++++----------------------
>  2 files changed, 32 insertions(+), 23 deletions(-)
> 
> diff --git a/include/linux/irq.h b/include/linux/irq.h
> index bc4e066..4e0fcbb 100644
> --- a/include/linux/irq.h
> +++ b/include/linux/irq.h
> @@ -600,6 +600,7 @@ int __irq_alloc_descs(int irq, unsigned int from, unsigned int cnt, int node,
>  
>  void irq_free_descs(unsigned int irq, unsigned int cnt);
>  int irq_reserve_irqs(unsigned int from, unsigned int cnt);
> +int __irq_reserve_irqs(int irq, unsigned int from, unsigned int cnt);
>  
>  static inline void irq_free_desc(unsigned int irq)
>  {
> diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
> index 192a302..3b9fb92 100644
> --- a/kernel/irq/irqdesc.c
> +++ b/kernel/irq/irqdesc.c
> @@ -340,18 +340,15 @@ void irq_free_descs(unsigned int from, unsigned int cnt)
>  EXPORT_SYMBOL_GPL(irq_free_descs);
>  
>  /**
> - * irq_alloc_descs - allocate and initialize a range of irq descriptors
> - * @irq:	Allocate for specific irq number if irq >= 0
> + * __irq_reserve_descs - reserve and initialize a range of irq descriptors
> + * @irq:	Reserve for specific irq number if irq >= 0
>   * @from:	Start the search from this irq number
> - * @cnt:	Number of consecutive irqs to allocate.
> - * @node:	Preferred node on which the irq descriptor should be allocated
> - * @owner:	Owning module (can be NULL)
> + * @cnt:	Number of consecutive irqs to reserve.
>   *
>   * Returns the first irq number or error code
>   */
>  int __ref
> -__irq_alloc_descs(int irq, unsigned int from, unsigned int cnt, int node,
> -		  struct module *owner)
> +__irq_reserve_irqs(int irq, unsigned int from, unsigned int cnt)
>  {
>  	int start, ret;
>  
> @@ -369,7 +366,7 @@ __irq_alloc_descs(int irq, unsigned int from, unsigned int cnt, int node,
>  	start = bitmap_find_next_zero_area(allocated_irqs, IRQ_BITMAP_BITS,
>  					   from, cnt, 0);
>  	ret = -EEXIST;
> -	if (irq >=0 && start != irq)
> +	if (irq >= 0 && start != irq)
>  		goto err;
>  
>  	if (start + cnt > nr_irqs) {
> @@ -380,12 +377,36 @@ __irq_alloc_descs(int irq, unsigned int from, unsigned int cnt, int node,
>  
>  	bitmap_set(allocated_irqs, start, cnt);
>  	mutex_unlock(&sparse_irq_lock);
> -	return alloc_descs(start, cnt, node, owner);
> +	return start;
>  
>  err:
>  	mutex_unlock(&sparse_irq_lock);
>  	return ret;
>  }
> +
> +/**
> + * irq_alloc_descs - allocate and initialize a range of irq descriptors
> + * @irq:	Allocate for specific irq number if irq >= 0
> + * @from:	Start the search from this irq number
> + * @cnt:	Number of consecutive irqs to allocate.
> + * @node:	Preferred node on which the irq descriptor should be allocated
> + * @owner:	Owning module (can be NULL)
> + *
> + * Returns the first irq number or error code
> + */
> +int __ref
> +__irq_alloc_descs(int irq, unsigned int from, unsigned int cnt, int node,
> +		  struct module *owner)
> +{
> +	int start;
> +
> +	start = __irq_reserve_irqs(irq, from, cnt);
> +
> +	if (start < 0)
> +		return start;
> +
> +	return alloc_descs(start, cnt, node, owner);

I think alloc_descs() fail path is needed before return.

> +}
>  EXPORT_SYMBOL_GPL(__irq_alloc_descs);
>  
>  /**
> @@ -397,20 +418,7 @@ EXPORT_SYMBOL_GPL(__irq_alloc_descs);
>   */
>  int irq_reserve_irqs(unsigned int from, unsigned int cnt)
>  {
> -	unsigned int start;
> -	int ret = 0;
> -
> -	if (!cnt || (from + cnt) > nr_irqs)
> -		return -EINVAL;
> -
> -	mutex_lock(&sparse_irq_lock);
> -	start = bitmap_find_next_zero_area(allocated_irqs, nr_irqs, from, cnt, 0);
> -	if (start == from)
> -		bitmap_set(allocated_irqs, start, cnt);
> -	else
> -		ret = -EEXIST;
> -	mutex_unlock(&sparse_irq_lock);
> -	return ret;
> +	return __irq_reserve_irqs(from, from, cnt);
>  }
>  
>  /**
> -- 
> 1.8.1.4
> 

-- 
Regards,
Alexander Gordeev
agordeev@...hat.com
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