Messages in this thread | | | From | Thomas Gleixner <> | Subject | Re: [PATCH 1/3] genirq: Simplify cond_unmask_eoi_irq() | Date | Wed, 30 Nov 2022 15:48:18 +0100 |
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Samuel!
On Sat, Nov 26 2022 at 17:41, Samuel Holland wrote:
> This function calls .irq_eoi in three places, making the logic hard to > follow. Rearrange the function so that .irq_eoi is called only once. > > The only time .irq_eoi is not called is when all three if checks fail, > so return early in that case. threads_oneshot can only be nonzero if > IRQS_ONESHOT is set, so the IRQS_ONESHOT check can be omitted there. > > The IRQS_ONESHOT condition from the first if statement must then be > copied to the unmask_irq() condition. > > Furthermore, if IRQS_ONESHOT is set, mask_irq() must have been called > in the parent function, so the irqd_irq_masked() check is redundant.
Not really convinced that all this is functionaly equivalent.
> static void cond_unmask_eoi_irq(struct irq_desc *desc, struct irq_chip *chip) > { > - if (!(desc->istate & IRQS_ONESHOT)) { > - chip->irq_eoi(&desc->irq_data); > + /* > + * Do not send an EOI if the thread will do it later in > + * unmask_threaded_irq(). > + */ > + if ((chip->flags & IRQCHIP_EOI_THREADED) && desc->threads_oneshot) > return; > - } > + > + chip->irq_eoi(&desc->irq_data);
This now issues EOI when the interrupt is in disabled state, which was not done before. That's probably a non-issue, but clearly a undocumented change.
> + > /* > * We need to unmask in the following cases: > * - Oneshot irq which did not wake the thread (caused by a > @@ -669,12 +674,8 @@ static void cond_unmask_eoi_irq(struct irq_desc *desc, struct irq_chip *chip) > * completely). > */ > if (!irqd_irq_disabled(&desc->irq_data) && > - irqd_irq_masked(&desc->irq_data) && !desc->threads_oneshot) { > - chip->irq_eoi(&desc->irq_data); > + (desc->istate & IRQS_ONESHOT) && !desc->threads_oneshot) > unmask_irq(desc);
This breaks the mask logic of handle_fasteoi_mask_irq() for an interrupt which does not have IRQS_ONESHOT set.
So no, it's not the same and it even breaks stuff.
Thanks,
tglx
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