On 2014/1/3 8:05, Yinghai Lu wrote:
> For ioapic hot-add support, it would be easy if we have continuous
> irq numbers for hot added ioapic controller.
>
> We can reserve irq range at first, and later allocate desc for those
> pre-reserved irqs when they are needed.
>
> The reasons for not allocating them during reserving:
> 1. only several pins of one ioapic are used, allocate for all pins, will
> waste memory for not used pins.
> 2. allocate later when is needed could make sure irq_desc is allocated
> on local node ram, as dev->node is set at that point.
>
> -v2: update changelog by adding reasons, requested by Konrad.
> -v3: according to tglx:
> separate core code change with arch code change.
> change function name to irq_alloc_reserved_desc.
> kill __irq_is_reserved().
> remove not need exports.
> according to Sebastian:
> spare one comments by put two functions together.
>
> Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>
> Cc: Joerg Roedel <joro@xxxxxxxxxx>
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> Cc: Sebastian Andrzej Siewior <sebastian@xxxxxxxxxxxxx>
> ---
> include/linux/irq.h | 3 +++
> kernel/irq/irqdesc.c | 23 +++++++++++++++++++++++
> 2 files changed, 26 insertions(+)
>
> diff --git a/include/linux/irq.h b/include/linux/irq.h
> index 0229caf..e5f6493 100644
> --- a/include/linux/irq.h
> +++ b/include/linux/irq.h
> @@ -595,10 +595,13 @@ static inline u32 irq_get_trigger_type(unsigned int irq)
>
> int __irq_alloc_descs(int irq, unsigned int from, unsigned int cnt, int node,
> struct module *owner);
> +int __irq_alloc_reserved_desc(int at, int node, struct module *owner);
>
> /* use macros to avoid needing export.h for THIS_MODULE */
> #define irq_alloc_descs(irq, from, cnt, node) \
> __irq_alloc_descs(irq, from, cnt, node, THIS_MODULE)
> +#define irq_alloc_reserved_desc_at(at, node) \
> + __irq_alloc_reserved_desc(at, node, THIS_MODULE)
>
> #define irq_alloc_desc(node) \
> irq_alloc_descs(-1, 0, 1, node)
> diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
> index a151db6..1166545 100644
> --- a/kernel/irq/irqdesc.c
> +++ b/kernel/irq/irqdesc.c
> @@ -410,6 +410,29 @@ __irq_alloc_descs(int irq, unsigned int from, unsigned int cnt, int node,
> EXPORT_SYMBOL_GPL(__irq_alloc_descs);
>
> /**
> + * __irq_alloc_reserved_desc - allocate irq descriptor for irq that is already reserved
> + * @irq: Allocate for specific irq number if irq >= 0
Hi Yinghai
Should we skip "if irq >= 0" here because irq should have already been
reserved? Or should we add range check for irq?
Thanks!
Gerry
> + * @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_alloc_reserved_desc(int irq, int node, struct module *owner)
> +{
> + mutex_lock(&sparse_irq_lock);
> + if (!test_bit(irq, allocated_irqs)) {
> + mutex_unlock(&sparse_irq_lock);
> + return -EINVAL;
> + }
> + mutex_unlock(&sparse_irq_lock);
> +
> + if (irq_to_desc(irq))
> + return irq;
> +
> + return alloc_descs(irq, 1, node, owner);
> +}
> +
> +/**
> * irq_reserve_irqs - mark irqs allocated
> * @from: mark from irq number
> * @cnt: number of irqs to mark
>
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