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

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

[Kunihiko Hayashi]

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.

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

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

[Bjorn Helgaas]

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
> 

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

[Kunihiko Hayashi]

Hi Bjorn,
Thank you for checking.

On 2021/08/19 20:29, Bjorn Helgaas wrote:
> Possibly update subject to be more descriptive, along lines of:
> 
>    Serialize INTx masking/unmasking

Okay, I'll apply it to the subject.

> 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.

I see. I'll rewrite the message to convey it more directly.

Thank you,

---
Best Regards
Kunihiko Hayashi