Messages in this thread Patch in this message | | | Date | Wed, 29 Oct 2014 11:26:24 +0100 (CET) | From | Thomas Gleixner <> | Subject | Re: [PATCH 1/3] genirq: Add support for priority-drop/deactivate interrupt controllers |
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On Wed, 29 Oct 2014, Marc Zyngier wrote: > On 28/10/14 20:14, Thomas Gleixner wrote: > > irq_enable() calls chip->irq_unmask(), i.e. DIR. So that clears the > > ACTIVE bit and then the IRQ either gets resent by hardware (in case of > > level as the device interrupt is still active) or retriggered by the > > irq_retrigger() callback. > > The problem I see here is for an interrupt that has been flagged as > disabled with irq_disabled(), but that hasn't fired. We'd end up doing a > DIR on something that hasn't had an EOI first. I think that's the only > wrinkle in this scheme.
Right. So the untested patch below should do the trick and prevent irq_enable() to invoke irq_unmask() if the interrupt is not flagged masked. And it only can be flagged masked if it was masked in the handler. The startup callback will make sure that irq_enable() is not invoked at startup time.
Thanks,
tglx
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diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c index e5202f00cabc..9c0f73e1994a 100644 --- a/kernel/irq/chip.c +++ b/kernel/irq/chip.c @@ -182,7 +182,7 @@ int irq_startup(struct irq_desc *desc, bool resend) ret = desc->irq_data.chip->irq_startup(&desc->irq_data); irq_state_clr_masked(desc); } else { - irq_enable(desc); + irq_enable(desc, false); } if (resend) check_irq_resend(desc, desc->irq_data.irq); @@ -202,13 +202,14 @@ void irq_shutdown(struct irq_desc *desc) irq_state_set_masked(desc); } -void irq_enable(struct irq_desc *desc) +void irq_enable(struct irq_desc *desc, bool ifmasked) { irq_state_clr_disabled(desc); - if (desc->irq_data.chip->irq_enable) + if (desc->irq_data.chip->irq_enable) { desc->irq_data.chip->irq_enable(&desc->irq_data); - else + } else if (!ifmasked || irqd_irq_masked(&desc->irq_data)) { desc->irq_data.chip->irq_unmask(&desc->irq_data); + } irq_state_clr_masked(desc); } diff --git a/kernel/irq/internals.h b/kernel/irq/internals.h index 4332d766619d..6eff2678cf6d 100644 --- a/kernel/irq/internals.h +++ b/kernel/irq/internals.h @@ -68,7 +68,7 @@ extern void __enable_irq(struct irq_desc *desc, unsigned int irq); extern int irq_startup(struct irq_desc *desc, bool resend); extern void irq_shutdown(struct irq_desc *desc); -extern void irq_enable(struct irq_desc *desc); +extern void irq_enable(struct irq_desc *desc, bool ifmasked); extern void irq_disable(struct irq_desc *desc); extern void irq_percpu_enable(struct irq_desc *desc, unsigned int cpu); extern void irq_percpu_disable(struct irq_desc *desc, unsigned int cpu); diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c index 0a9104b4608b..d8c474608c2d 100644 --- a/kernel/irq/manage.c +++ b/kernel/irq/manage.c @@ -448,7 +448,7 @@ void __enable_irq(struct irq_desc *desc, unsigned int irq) goto err_out; /* Prevent probing on this irq: */ irq_settings_set_noprobe(desc); - irq_enable(desc); + irq_enable(desc, true); check_irq_resend(desc, irq); /* fall-through */ }
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