Re: [PATCH] PCI: uniphier: Take lock in INTX irq_{mask,unmask,ack} callbacks

[Bjorn Helgaas <helgaas@kernel.org>]

Possibly update subject to be more descriptive, along lines of:

  Serialize INTx masking/unmasking

On Thu, Aug 19, 2021 at 07:56:06PM +0900, Kunihiko Hayashi wrote:
> The same condition register PCI_RCV_INTX is used in irq_mask(),
> irq_unmask() and irq_ack() callbacks. Accesses to register can occur at the
> same time without lock.
> This introduces a lock into the callbacks to prevent the issue.

Rewrap into a single paragraph or add blank line between paragraphs.

s/This introduces/Add/ to make this an imperative description of what
you want this patch to do.  No need for "This" since the context is
obvious.

> Fixes: 7e6d5cd88a6f ("PCI: uniphier: Add UniPhier PCIe host controller support")
> Suggested-by: Pali Rohár <pali@kernel.org>
> Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
> ---
>  drivers/pci/controller/dwc/pcie-uniphier.c | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-uniphier.c b/drivers/pci/controller/dwc/pcie-uniphier.c
> index ebe43e9..5075714 100644
> --- a/drivers/pci/controller/dwc/pcie-uniphier.c
> +++ b/drivers/pci/controller/dwc/pcie-uniphier.c
> @@ -186,12 +186,17 @@ static void uniphier_pcie_irq_ack(struct irq_data *d)
>  	struct pcie_port *pp = irq_data_get_irq_chip_data(d);
>  	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
>  	struct uniphier_pcie_priv *priv = to_uniphier_pcie(pci);
> +	unsigned long flags;
>  	u32 val;
>  
> +	raw_spin_lock_irqsave(&pp->lock, flags);
> +
>  	val = readl(priv->base + PCL_RCV_INTX);
>  	val &= ~PCL_RCV_INTX_ALL_STATUS;
>  	val |= BIT(irqd_to_hwirq(d) + PCL_RCV_INTX_STATUS_SHIFT);
>  	writel(val, priv->base + PCL_RCV_INTX);
> +
> +	raw_spin_unlock_irqrestore(&pp->lock, flags);
>  }
>  
>  static void uniphier_pcie_irq_mask(struct irq_data *d)
> @@ -199,12 +204,17 @@ static void uniphier_pcie_irq_mask(struct irq_data *d)
>  	struct pcie_port *pp = irq_data_get_irq_chip_data(d);
>  	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
>  	struct uniphier_pcie_priv *priv = to_uniphier_pcie(pci);
> +	unsigned long flags;
>  	u32 val;
>  
> +	raw_spin_lock_irqsave(&pp->lock, flags);
> +
>  	val = readl(priv->base + PCL_RCV_INTX);
>  	val &= ~PCL_RCV_INTX_ALL_MASK;
>  	val |= BIT(irqd_to_hwirq(d) + PCL_RCV_INTX_MASK_SHIFT);
>  	writel(val, priv->base + PCL_RCV_INTX);
> +
> +	raw_spin_unlock_irqrestore(&pp->lock, flags);
>  }
>  
>  static void uniphier_pcie_irq_unmask(struct irq_data *d)
> @@ -212,12 +222,17 @@ static void uniphier_pcie_irq_unmask(struct irq_data *d)
>  	struct pcie_port *pp = irq_data_get_irq_chip_data(d);
>  	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
>  	struct uniphier_pcie_priv *priv = to_uniphier_pcie(pci);
> +	unsigned long flags;
>  	u32 val;
>  
> +	raw_spin_lock_irqsave(&pp->lock, flags);
> +
>  	val = readl(priv->base + PCL_RCV_INTX);
>  	val &= ~PCL_RCV_INTX_ALL_MASK;
>  	val &= ~BIT(irqd_to_hwirq(d) + PCL_RCV_INTX_MASK_SHIFT);
>  	writel(val, priv->base + PCL_RCV_INTX);
> +
> +	raw_spin_unlock_irqrestore(&pp->lock, flags);
>  }
>  
>  static struct irq_chip uniphier_pcie_irq_chip = {
> -- 
> 2.7.4
>