On 20/04/16 12:03, Jon Hunter wrote:
> When mapping an IRQ, it is possible that a mapping for the IRQ already
> exists. If mapping does exist then there are the following issues with
> regard to the handling of the IRQ type settings ...
> 1. If the domain is part of a hierarchy, then:
> a. We do not check that the type settings for the existing mapping
> match those of the new mapping.
> b. We do not check to see if the type settings have been programmed
> yet (and they might not have been) and so we may never set the
> type.
> 2. If the domain is NOT part of a hierarchy, we will overwrite the
> current type settings programmed if they are different from the
> previous mapping. Please note that irq_create_mapping()
> calls irq_find_mapping() to check if a mapping already exists.
>
> Although, it may be unlikely that the type settings for a shared
> interrupt would not match, nonetheless we should check for this.
> Therefore, to fix this check if a mapping exists (regardless of whether
> the domain is part of a hierarchy or not) and if it does then:
> 1. Return the IRQ number if the type settings match or are not
> specified.
> 2. Program the type settings and return the IRQ number if the type
> settings have not been programmed yet.
> 3. Otherwise if the type setting do not match, then print a warning
> and don't return the IRQ number.
>
> Furthermore, add a warning if the type return by irq_domain_translate()
> has bits outside the sense mask set and then clear these bits. If these
> bits are not cleared then this will cause the comparision of the type
> settings for an existing mapping to fail with that of the new mapping
> even if the sense bit themselves match. The reason being is that the
> existing type settings are read by calling irq_get_trigger_type() which
> will clear any bits outside the sense mask. This will allow us to detect
> irqchips that are not correctly clearing these bits and fix them.
>
> Signed-off-by: Jon Hunter <jonathanh@xxxxxxxxxx>
> ---
> kernel/irq/irqdomain.c | 38 +++++++++++++++++++++++++++++++++-----
> 1 file changed, 33 insertions(+), 5 deletions(-)
>
> diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
> index 245a485ffb61..88e9328b7aab 100644
> --- a/kernel/irq/irqdomain.c
> +++ b/kernel/irq/irqdomain.c
> @@ -592,15 +592,43 @@ unsigned int irq_create_fwspec_mapping(struct irq_fwspec *fwspec)
> if (irq_domain_translate(domain, fwspec, &hwirq, &type))
> return 0;
>
> - if (irq_domain_is_hierarchy(domain)) {
> + /*
> + * WARN if the irqchip returns a type with bits
> + * outside the sense mask set and clear these bits.
> + */
> + if (WARN_ON(type & ~IRQ_TYPE_SENSE_MASK))
> + type &= IRQ_TYPE_SENSE_MASK;
> +
> + /*
> + * If we've already configured this interrupt,
> + * don't do it again, or hell will break loose.
> + */
> + virq = irq_find_mapping(domain, hwirq);
> + if (virq) {
> /*
> - * If we've already configured this interrupt,
> - * don't do it again, or hell will break loose.
> + * If the trigger type is not specified or matches the
> + * current trigger type then we are done so return the
> + * interrupt number. Otherwise, if the trigger type does
> + * not match return 0.
I think I should have dropped this 'otherwise' sentence from here.
Jon
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