Messages in this thread Patch in this message | | | Date | Sun, 9 Nov 2008 08:38:13 +0100 | From | Ingo Molnar <> | Subject | Re: [RFC PATCH] sparse_irq aka dyn_irq |
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General impression: very nice patch!
A lot of the structural problems have been addressed: the descriptor lookup is now hashed, the dynarray stuff got cleaned up / eliminated, the irq_desc->chip_data binding is very nice as well.
(And the patch needs to be split up like it was in the past, once all review feedback has been seen and addressed.)
> +config HAVE_SPARSE_IRQ > + bool > + default y
i think it should be made user-configurable - at least initially. It should not cause extra complications, right?
> + if (irq < NR_IRQS_LEGACY) {
please s/NR_IRQS_LEGACY/NR_IRQS_X86_LEGACY - this is never used outside of x86 code.
> + cfg_new = desc_new->chip_data;
the chip_data binding is a nice touch.
> - irq_want = build_irq_for_pci_dev(dev) + 0x100; > + irq_want = build_irq_for_pci_dev(dev) + 0xfff;
please replace magic constant with a properly named constant.
> - if (WARN_ON(nr > NR_IRQS)) > - nr = NR_IRQS;
this will have to stay for the !SPARSE_IRQ case.
> +++ linux-2.6/arch/x86/mm/init_32.c > @@ -66,6 +66,7 @@ static unsigned long __meminitdata table > static unsigned long __meminitdata table_top; > > static int __initdata after_init_bootmem; > +int after_bootmem; > > static __init void *alloc_low_page(unsigned long *phys) > { > @@ -987,6 +988,8 @@ void __init mem_init(void) > > set_highmem_pages_init(); > > + after_bootmem = 1;
this hack can go away once we have a proper percpu_alloc() that can be used early enough.
> +#ifndef CONFIG_HAVE_SPARSE_IRQ
i'd suggest s/HAVE_SPARSE_IRQ/SPARSE_IRQ - as the HAVE_* flags are for architecture code to signal the presence of a facility.
> +#ifndef CONFIG_HAVE_SPARSE_IRQ > if (irq >= nr_irqs) > return; > +#endif
we should hide as many ugly #ifdefs as possible, and define nr_irqs to NR_IRQS in the !SPARSE_IRQ case.
> +++ linux-2.6/drivers/pci/htirq.c > @@ -82,6 +82,18 @@ void unmask_ht_irq(unsigned int irq) > write_ht_irq_msg(irq, &msg); > } > > +static unsigned int build_irq_for_pci_dev(struct pci_dev *dev) > +{ > + unsigned int irq; > + > + irq = dev->bus->number; > + irq <<= 8; > + irq |= dev->devfn; > + irq <<= 12; > + > + return irq;
magic constants should be named.
> +#ifdef CONFIG_HAVE_SPARSE_IRQ > + irq = create_irq_nr(irq_want + idx); > +#else > irq = create_irq(); > +#endif
please eliminate this #ifdef by adding one new API: create_irq_nr(idx), which just maps to the create_irq() API in the !SPARSE_IRQ case.
> static struct irq_2_iommu *irq_2_iommu(unsigned int irq) > { > - return (irq < nr_irqs) ? irq_2_iommuX + irq : NULL; > + struct irq_desc *desc; > + > + desc = irq_to_desc(irq); > + > + BUG_ON(!desc); > + > + return desc->irq_2_iommu;
the BUG_ON() is not too friendly, please do something like this instead:
if (WARN_ON_ONCE(!desc)) return NULL;
> +#ifndef CONFIG_HAVE_SPARSE_IRQ > /* protect irq_2_iommu_alloc later */ > if (irq >= nr_irqs) > return -1; > +#endif
this #ifdef can be eliminated too and turned into straight code via the #define nr_irqs NR_IRQS trick in the !SPARSE_IRQ case.
> - for_each_irq_desc(i, desc) > + for_each_irq_desc(i, desc) { > desc->affinity = cpumask_of_cpu(0); > + } end_for_each_irq_desc();
Sidenote: later on, once the patch is upstream, we should do a global rename:
s/for_each_irq_desc/do_each_irq_desc s/end_for_each_irq_desc/while_each_irq_desc
as it's much harder to miss the "while" in a "do ..." loop, than it is to miss the "end" in a "for" loop.
> +#ifdef CONFIG_HAVE_SPARSE_IRQ > +static struct irq_desc irq_desc_init = { > + .irq = -1U, > + .status = IRQ_DISABLED, > + .chip = &no_irq_chip, > + .handle_irq = handle_bad_irq, > + .depth = 1, > + .lock = __SPIN_LOCK_UNLOCKED(irq_desc_init.lock), > +#ifdef CONFIG_SMP > + .affinity = CPU_MASK_ALL > +#endif > +};
please align structure fields vertically.
> +static struct irq_desc irq_desc_legacy[NR_IRQS_LEGACY] __cacheline_aligned_in_smp = { > + [0 ... NR_IRQS_LEGACY-1] = { > + .irq = -1U, > + .status = IRQ_DISABLED, > + .chip = &no_irq_chip, > + .handle_irq = handle_bad_irq, > + .depth = 1, > + .lock = __SPIN_LOCK_UNLOCKED(irq_desc_init.lock), > +#ifdef CONFIG_SMP > + .affinity = CPU_MASK_ALL > +#endif > + } > +};
same here.
> @@ -199,7 +200,6 @@ extern void reinit_intr_remapped_IO_APIC > #endif > > extern int probe_nr_irqs(void); > - > #else /* !CONFIG_X86_IO_APIC */ > #define io_apic_assign_pci_irqs 0 > static const int timer_through_8259 = 0;
that's a spurious removal of a newline.
all in one, i cannot see fundamental problems in this patch.
Ingo
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