Re: [Xen-devel] [RFC PATCH 04/10] ARM: vGIC: add struct pending_irq locking

[Julien Grall <julien.grall@xxxxxxx>]

On 04/05/17 16:31, Andre Przywara wrote:
> diff --git a/xen/arch/arm/vgic.c b/xen/arch/arm/vgic.c
> index f4ae454..44363bb 100644
> --- a/xen/arch/arm/vgic.c
> +++ b/xen/arch/arm/vgic.c
> @@ -356,11 +356,16 @@ void vgic_enable_irqs(struct vcpu *v, uint32_t r, int n)
>      while ( (i = find_next_bit(&mask, 32, i)) < 32 ) {
>          irq = i + (32 * n);
>          v_target = vgic_get_target_vcpu(v, irq);
> +
> +        spin_lock_irqsave(&v_target->arch.vgic.lock, flags);
>          p = irq_to_pending(v_target, irq);
> +        spin_lock(&p->lock);
> +
>          set_bit(GIC_IRQ_GUEST_ENABLED, &p->status);
> -        spin_lock_irqsave(&v_target->arch.vgic.lock, flags);
> +
>          if ( !list_empty(&p->inflight) && !test_bit(GIC_IRQ_GUEST_VISIBLE, 
> &p->status) )
>              gic_raise_guest_irq(v_target, p);
> +        spin_unlock(&p->lock);
Why does the lock not cover p->desc below?

>          spin_unlock_irqrestore(&v_target->arch.vgic.lock, flags);
>          if ( p->desc != NULL )
>          {
--
Julien Grall

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