[v2,12/26] x86, irq: Add realloc_irq_and_cfg_at()

For ioapic hotplug support, we need to reserve irq range for hot
added ioapic controller. After that we need to allocate those
pre-reserved one.

Add realloc_irq_and_cfg_at() to really allocate irq_desc and cfg
as pre-reserved only hold bit in allocate_irqs bit maps.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
---
 arch/x86/kernel/apic/io_apic.c |   32 +++++++++++++++++++++++++++++++-
 include/linux/irq.h            |    5 +++++
 kernel/irq/irqdesc.c           |   26 ++++++++++++++++++++++++++
 3 files changed, 62 insertions(+), 1 deletion(-)

On Fri, Feb 08, 2013 at 11:28:09AM -0800, Yinghai Lu wrote:
> For ioapic hotplug support, we need to reserve irq range for hot
> added ioapic controller. After that we need to allocate those
> pre-reserved one.
> 
> Add realloc_irq_and_cfg_at() to really allocate irq_desc and cfg

Put a period at 'cfg'.
> as pre-reserved only hold bit in allocate_irqs bit maps.

And then start the new sentence here saying 'Pre-reserved (XX function
name) only holds bits in .."

> 
> Signed-off-by: Yinghai Lu <yinghai@kernel.org>
> Cc: Joerg Roedel <joro@8bytes.org>
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
> ---
>  arch/x86/kernel/apic/io_apic.c |   32 +++++++++++++++++++++++++++++++-
>  include/linux/irq.h            |    5 +++++
>  kernel/irq/irqdesc.c           |   26 ++++++++++++++++++++++++++
>  3 files changed, 62 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
> index d2b4988..72a1351 100644
> --- a/arch/x86/kernel/apic/io_apic.c
> +++ b/arch/x86/kernel/apic/io_apic.c
> @@ -301,6 +301,36 @@ static void free_irq_at(unsigned int at, struct irq_cfg *cfg)
>  	irq_free_desc(at);
>  }
>  
> +static struct irq_cfg *realloc_irq_and_cfg_at(unsigned int at, int node)
> +{
> +	struct irq_desc *desc = irq_to_desc(at);
> +	struct irq_cfg *cfg;
> +	int res;
> +
> +	if (desc) {
> +		if (irq_desc_get_irq_data(desc)->node == node)
> +			return alloc_irq_and_cfg_at(at, node);
> +
> +		cfg = irq_desc_get_chip_data(desc);
> +		if (cfg) {
> +			/* shared irq */
> +			if (!list_empty(&cfg->irq_2_pin))
> +				return cfg;
> +			free_irq_cfg(at, cfg);
> +		}
> +	}
> +
> +	res = irq_realloc_desc_at(at, node);
> +	if (res >= 0) {
> +		cfg = alloc_irq_cfg(at, node);
> +		if (cfg) {
> +			irq_set_chip_data(at, cfg);
> +			return cfg;
> +		}
> +	}
> +
> +	return alloc_irq_and_cfg_at(at, node);
> +}
>  
>  struct io_apic {
>  	unsigned int index;
> @@ -3355,7 +3385,7 @@ int arch_setup_ht_irq(unsigned int irq, struct pci_dev *dev)
>  static int
>  io_apic_setup_irq_pin(unsigned int irq, int node, struct io_apic_irq_attr *attr)
>  {
> -	struct irq_cfg *cfg = alloc_irq_and_cfg_at(irq, node);
> +	struct irq_cfg *cfg = realloc_irq_and_cfg_at(irq, node);
>  	int ret;
>  
>  	if (!cfg)
> diff --git a/include/linux/irq.h b/include/linux/irq.h
> index 4e0fcbb..9c6c047 100644
> --- a/include/linux/irq.h
> +++ b/include/linux/irq.h
> @@ -602,6 +602,11 @@ 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);
>  
> +int __irq_realloc_desc(int at, int node, struct module *owner);
> +/* use macros to avoid needing export.h for THIS_MODULE */
> +#define irq_realloc_desc_at(at, node)	\
> +	__irq_realloc_desc(at, node, THIS_MODULE)
> +
>  static inline void irq_free_desc(unsigned int irq)
>  {
>  	irq_free_descs(irq, 1);
> diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
> index 3b9fb92..b48f65b 100644
> --- a/kernel/irq/irqdesc.c
> +++ b/kernel/irq/irqdesc.c
> @@ -99,6 +99,11 @@ EXPORT_SYMBOL_GPL(nr_irqs);
>  static DEFINE_MUTEX(sparse_irq_lock);
>  static DECLARE_BITMAP(allocated_irqs, IRQ_BITMAP_BITS);
>  
> +static bool __irq_is_reserved(int irq)
> +{
> +	return !!test_bit(irq, allocated_irqs);
> +}
> +
>  #ifdef CONFIG_SPARSE_IRQ
>  
>  static RADIX_TREE(irq_desc_tree, GFP_KERNEL);
> @@ -410,6 +415,27 @@ __irq_alloc_descs(int irq, unsigned int from, unsigned int cnt, int node,
>  EXPORT_SYMBOL_GPL(__irq_alloc_descs);
>  
>  /**
> + * irq_realloc_desc - allocate irq descriptor for irq that is already reserved

Which begs the question - why was it not allocated when it was reserved?

> + * @irq:	Allocate for specific irq number if irq >= 0
> + * @node:	Preferred node on which the irq descriptor should be allocated
> + * @owner:	Owning module (can be NULL)
> + *
> + * Returns the irq number or error code
> + */
> +int __ref
> +__irq_realloc_desc(int irq, int node, struct module *owner)
> +{
> +	if (!__irq_is_reserved(irq))
> +		return -EINVAL;
> +
> +	if (irq_to_desc(irq))
> +		free_desc(irq);
> +
> +	return alloc_descs(irq, 1, node, owner);
> +}
> +EXPORT_SYMBOL_GPL(__irq_realloc_desc);
> +
> +/**
>   * irq_reserve_irqs - mark irqs allocated
>   * @from:	mark from irq number
>   * @cnt:	number of irqs to mark
> -- 
> 1.7.10.4
> 
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On Fri, Mar 8, 2013 at 11:53 AM, Konrad Rzeszutek Wilk
<konrad.wilk@oracle.com> wrote:
>> + * irq_realloc_desc - allocate irq descriptor for irq that is already reserved
>
> Which begs the question - why was it not allocated when it was reserved?

The reasons for not allocating them during reserving:
1. only several pins in ioapic are used, allocate for them pin, will
   waste memory for not used one.
2. relocate later could make sure irq_desc is allocated on local node ram.

Thanks

Yinghai
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