On Sat, Feb 22, 2014 at 3:38 PM, Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:
>
> OMG, you really mean that:
>
> +++ b/arch/alpha/kernel/irq_i8259.c
> @@ -92,6 +92,7 @@ init_i8259a_irqs(void)
> outb(0xff, 0xA1); /* mask all of 8259A-2 */
>
> for (i = 0; i < 16; i++) {
> + irq_alloc_desc_at(i, 0);
> irq_set_chip_and_handler(i, &i8259a_irq_type, handle_level_irq);
> }
>
> You can't be serious about that. There are tons of ways to call into
> the core and access an irq descriptor aside of irq_set_chip* before it
> is potentially allocated.
>
> Are you going to analyze all of them and add an irq_alloc_desc_at()
> before that call?
>
> HELL, NO!
>
> I'm really tired of that.
>
> Stay away from kernel/irq/* and wait for people who are competent
> enough and willing to spend the extra thoughts to come up with
> solutions which are not completely ass backwards.
oh, no, sorry for annoying you again.
In the irq_alloc_desc_at() path for !SPARSE_IRQ, it should not touch anything
except setting that bit in allocated_irqs bitmap.
Or could just replace irq_reserve_irq in irq_set_chip(), in that way will avoid
touching arch codes.
like
diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index dc04c16..02d6ad0 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -28,8 +28,13 @@
int irq_set_chip(unsigned int irq, struct irq_chip *chip)
{
unsigned long flags;
- struct irq_desc *desc = irq_get_desc_lock(irq, &flags, 0);
+ struct irq_desc *desc;
+
+#ifndef CONFIG_SPARSE_IRQ
+ irq_alloc_desc_at(irq, 0);
+#endif
+ desc = irq_get_desc_lock(irq, &flags, 0);
if (!desc)
return -EINVAL;
@@ -38,12 +43,7 @@ int irq_set_chip(unsigned int irq, struct irq_chip *chip)
desc->irq_data.chip = chip;
irq_put_desc_unlock(desc, flags);
- /*
- * For !CONFIG_SPARSE_IRQ make the irq show up in
- * allocated_irqs. For the CONFIG_SPARSE_IRQ case, it is
- * already marked, and this call is harmless.
- */
- irq_reserve_irq(irq);
+
return 0;
}
EXPORT_SYMBOL(irq_set_chip);
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