Re: [Xen-devel] [RFC Patch] x86/hpet: Disable interrupts while running hpet interrupt handler.

[Keir Fraser <keir.xen@xxxxxxxxx>]

On 05/08/2013 21:38, "Andrew Cooper" <andrew.cooper3@xxxxxxxxxx> wrote:

> The hpet interrupt handler runs with interrupts enabled, due to this the
> spin_unlock_irq() in:
> 
>     while ( desc->status & IRQ_PENDING )
>     {
>         desc->status &= ~IRQ_PENDING;
>         spin_unlock_irq(&desc->lock);
>         tsc_in = tb_init_done ? get_cycles() : 0;
>         action->handler(irq, action->dev_id, regs);
>         TRACE_3D(TRC_HW_IRQ_HANDLED, irq, tsc_in, get_cycles());
>         spin_lock_irq(&desc->lock);
>     }
> 
> in do_IRQ().

But the handler sets IRQ_INPROGRESS before entering this loop, which should
prevent reentry of the irq handler (hpet_interrupt_handler). So I don't see
how the multiple reentering of hpet_interrupt_handler in the call trace is
possible.

 -- Keir



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