Messages in this thread | | | Date | Mon, 10 Jun 2013 22:13:44 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: [PATCH v3 11/27] x86, irq: Add realloc_irq_and_cfg_at() |
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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@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 ++++++++++++++++++++++++++
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
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