Messages in this thread | | | Date | Sat, 27 May 2017 10:30:51 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: [PATCH v2] genirq: Check irq disabled & masked states in irq_shutdown |
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On Sat, 27 May 2017, Jeffy Chen wrote:
> If a irq is already disabled & masked, free_irq may cause a unbalanced > irq shutdown/disable/mask, for example:
No, it's not. irq_shutdown/disable/mask are low level access functions which can be invoked at any given time.
The only interface which has refcounting is disable/enable_irq().
> devm_request_irq->irq_startup->irq_enable > disable_irq <-- disabled and masked > devm_free_irq->irq_shutdown <-- try to disable it again > > This would confuse some pinctrl drivers which would control clk in > irq_enable/irq_disable, for example pinctrl-rockchip/pinctrl-nomadik. > > This patch add a state check in irq_shutdown to prevent that.
Please read Documentation/process/SubmittingPatches and search for "this patch".
> diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c > index 686be4b..816da03 100644 > --- a/kernel/irq/chip.c > +++ b/kernel/irq/chip.c > @@ -206,14 +206,20 @@ int irq_startup(struct irq_desc *desc, bool resend) > > void irq_shutdown(struct irq_desc *desc) > { > - irq_state_set_disabled(desc); > desc->depth = 1; > + > + if (unlikely(irqd_irq_disabled(&desc->irq_data) && > + irqd_irq_masked(&desc->irq_data))) > + goto out;
This is just wrong.
It's perfectly legit to call disable_irq() and then free_irq(). Still free_irq() has to be able to invoke chip->irq_shutdown(). Preventing that will leave some interrupt chips in a half initialized state.
The irq core does not guarntee that the unmask/mask enable/disable startup/shutdown callbacks are perfectly balanced. irq_shutdown() is only one place where this can happen. This needs more thought than this 'works for me' hackery.
Thanks,
tglx
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