Re: [2/3] PCI: designware: Take lock when ACKing an interrupt

[Niklas Cassel <niklas.cassel@linaro.org>]

On Tue, Nov 13, 2018 at 10:57:33PM +0000, Marc Zyngier wrote:
> Bizarrely, there is no lock taken in the irq_ack helper. This
> puts the ack callback provided by a specific platform in a awkward
> situation where there is no synchronization that would be expected
> on other callback.
> 
> Introduce the required lock, giving some level of uniformity among
> callbacks.
> 
> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
> ---
>  drivers/pci/controller/dwc/pcie-designware-host.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
> index c3aa8b5fb51d..0a76948ed49e 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> @@ -202,11 +202,16 @@ static void dw_pci_bottom_ack(struct irq_data *d)
>  {
>  	struct msi_desc *msi = irq_data_get_msi_desc(d);
>  	struct pcie_port *pp;
> +	unsigned long flags;
>  
>  	pp = msi_desc_to_pci_sysdata(msi);
>  
> +	raw_spin_lock_irqsave(&pp->lock, flags);
> +
>  	if (pp->ops->msi_irq_ack)
>  		pp->ops->msi_irq_ack(d->hwirq, pp);
> +
> +	raw_spin_unlock_irqrestore(&pp->lock, flags);
>  }
>  
>  static struct irq_chip dw_pci_msi_bottom_irq_chip = {

Tested-by: Niklas Cassel <niklas.cassel@linaro.org>