Re: [PATCH 1/4] x86_64 io_apic: Implement remove_pin_to_irq

From: Eric W. Biederman
Date: Mon Jan 08 2007 - 16:31:42 EST


"Lu, Yinghai" <yinghai.lu@xxxxxxx> writes:

> -----Original Message-----
> From: ebiederm@xxxxxxxxxxxx [mailto:ebiederm@xxxxxxxxxxxx]
> Sent: Monday, January 08, 2007 7:50 AM
> To: Linus Torvalds
> Cc: Tobias Diedrich; Lu, Yinghai; Andrew Morton; Adrian Bunk; Andi
> Kleen; Linux Kernel Mailing List
> Subject: [PATCH 1/4] x86_64 io_apic: Implement remove_pin_to_irq
>
> +static void remove_pin_to_irq(unsigned int irq, int apic, int pin)
> +{
> + struct irq_pin_list *entry = irq_2_pin + irq;
>
> You may need to update add_pin_to_irq to avoid multi entries for irq 0.

Any updates to add_pin_to_irq are wrong. It works fine. If there
is something wrong we need to fix remove_pin_to_irq.

What is the problem you see? Sorry I'm dense at the moment.

I preserve the invariant that irq_2_pin + irq is always the first
entry in the chain. I do this when I delete a multi chain entry
by copying the next entry over the current entry, and then freeing
(and leaking) the second entry in the chain.

Is there something wrong with that? I came within an inch of deleting
this multiple apic, pin to irq mapping code but the comments said it
is needed for some ioapic case. So in resurrecting this variant I may
have goofed somewhere.

Eric
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