On Fri, 7 Jun 2013, Yinghai Lu wrote:
> For ioapic hot-add support, it would be easy if we put all irqs
> for that ioapic controller together.
>
> We can reserve irq range at first, then reallocate those
No. We do not reallocate something which does not exist in the first
place.
> pre-reserved one when it is needed.
>
> Add realloc_irq_and_cfg_at() to really allocate irq_desc and cfg,
> because pre-reserved only mark bits in allocate_irqs bit maps.
>
> The reasons for not allocating them during reserving:
> 1. only several pins in ioapic are used, allocate for all pins, will
> waste memory for not used pins.
> 2. relocate later could make sure irq_desc is allocated on local node ram.
> as dev->node is set at that point.
This is not relocating. Your changelog sucks as much as your code.
> -v2: update changelog by adding reasons, requested by Konrad.
>
> 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>
> ---
> arch/x86/kernel/apic/io_apic.c | 32 +++++++++++++++++++++++++++++++-
> include/linux/irq.h | 5 +++++
> kernel/irq/irqdesc.c | 26 ++++++++++++++++++++++++++
No, we do not add new code to the core and use it in the same patch at
some random other place. The core code change wants to be separate and
have a separate changelog.
> --- 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 */
You must be kidding. export.h has been split out from module.h exactly
to avoid horrible comments like the above and nonsense like this:
> +#define irq_realloc_desc_at(at, node) \
> + __irq_realloc_desc(at, node, THIS_MODULE)
> +
> 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);
What's the point of this? Why not use test_bit() directly in the code?
If we really want this to be a function, then it should be inline and
it could do without the pointless and !! nonsense.
> 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
And of course you are documenting crap again.
> + * @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)
What's the point of this line split ?
> +{
> + if (!__irq_is_reserved(irq))
> + return -EINVAL;
So this function can operate safely w/o holding sparse_irq_lock?
> + if (irq_to_desc(irq))
> + free_desc(irq);
You unconditionally throw away an existing irq descriptor? No, you
should bail out here. The function name is a misnomer as it does not
match the funciton description:
irq_realloc_desc - allocate irq descriptor for irq that is already reserved
You want to allocate an irq descriptor for a reserved irq. That's what
the function is about, not about reallocating an existing irq
descriptor.
So what you want is:
irq_alloc_reserved_desc - allocate irq descriptor for irq that is already reserved
and then bail out if the irq descriptor already exists.
> + return alloc_descs(irq, 1, node, owner);
> +EXPORT_SYMBOL_GPL(__irq_realloc_desc);
What's the point of exporting this?
Thanks,
tglx
--
To unsubscribe from this list: send the line "unsubscribe linux-pci" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
