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* [PATCH] PCI: uniphier: Serialize INTx masking/unmasking
@ 2021-08-23 11:18 Kunihiko Hayashi
  2021-08-23 15:09 ` Pali Rohár
  0 siblings, 1 reply; 6+ messages in thread
From: Kunihiko Hayashi @ 2021-08-23 11:18 UTC (permalink / raw)
  To: Lorenzo Pieralisi, Rob Herring, Krzysztof Wilczyński, Bjorn Helgaas
  Cc: Pali Rohár, Masami Hiramatsu, linux-pci, linux-arm-kernel,
	linux-kernel, Kunihiko Hayashi

The 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 a lock.
Add a lock into each callback 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(+)

The previous patch is as follows:
https://lore.kernel.org/linux-pci/1629370566-29984-1-git-send-email-hayashi.kunihiko@socionext.com/

Changes in the previous patch:
- Change the subject and commit message

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


^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH] PCI: uniphier: Serialize INTx masking/unmasking
  2021-08-23 11:18 [PATCH] PCI: uniphier: Serialize INTx masking/unmasking Kunihiko Hayashi
@ 2021-08-23 15:09 ` Pali Rohár
  2021-08-23 16:57   ` Marc Zyngier
  0 siblings, 1 reply; 6+ messages in thread
From: Pali Rohár @ 2021-08-23 15:09 UTC (permalink / raw)
  To: Kunihiko Hayashi
  Cc: Marc Zyngier, Lorenzo Pieralisi, Rob Herring,
	Krzysztof Wilczyński, Bjorn Helgaas, Masami Hiramatsu,
	linux-pci, linux-arm-kernel, linux-kernel

+ Marc (who originally reported this issue)

On Monday 23 August 2021 20:18:20 Kunihiko Hayashi wrote:
> The 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 a lock.
> Add a lock into each callback 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>

Acked-by: Pali Rohár <pali@kernel.org>

> ---
>  drivers/pci/controller/dwc/pcie-uniphier.c | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> The previous patch is as follows:
> https://lore.kernel.org/linux-pci/1629370566-29984-1-git-send-email-hayashi.kunihiko@socionext.com/
> 
> Changes in the previous patch:
> - Change the subject and commit message
> 
> 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
> 

^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH] PCI: uniphier: Serialize INTx masking/unmasking
  2021-08-23 15:09 ` Pali Rohár
@ 2021-08-23 16:57   ` Marc Zyngier
  2021-08-25  0:01     ` Kunihiko Hayashi
  0 siblings, 1 reply; 6+ messages in thread
From: Marc Zyngier @ 2021-08-23 16:57 UTC (permalink / raw)
  To: Pali Rohár, Kunihiko Hayashi
  Cc: Lorenzo Pieralisi, Rob Herring, Krzysztof Wilczyński,
	Bjorn Helgaas, Masami Hiramatsu, linux-pci, linux-arm-kernel,
	linux-kernel

On Mon, 23 Aug 2021 16:09:27 +0100,
Pali Rohár <pali@kernel.org> wrote:
> 
> + Marc (who originally reported this issue)
> 
> On Monday 23 August 2021 20:18:20 Kunihiko Hayashi wrote:
> > The 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 a lock.
> > Add a lock into each callback 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>
> 
> Acked-by: Pali Rohár <pali@kernel.org>
> 
> > ---
> >  drivers/pci/controller/dwc/pcie-uniphier.c | 15 +++++++++++++++
> >  1 file changed, 15 insertions(+)
> > 
> > The previous patch is as follows:
> > https://lore.kernel.org/linux-pci/1629370566-29984-1-git-send-email-hayashi.kunihiko@socionext.com/
> > 
> > Changes in the previous patch:
> > - Change the subject and commit message
> > 
> > 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);

This looks extremely suspicious. You clear all the INTX mask bits, and
only set the one you need. How about the pre-existing bits?

> >  	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);

And by the same token, this second line is totally useless.

I think masking/unmasking is broken in this driver, locking or not.

	M.

-- 
Without deviation from the norm, progress is not possible.

^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH] PCI: uniphier: Serialize INTx masking/unmasking
  2021-08-23 16:57   ` Marc Zyngier
@ 2021-08-25  0:01     ` Kunihiko Hayashi
  2021-08-25  9:07       ` Marc Zyngier
  0 siblings, 1 reply; 6+ messages in thread
From: Kunihiko Hayashi @ 2021-08-25  0:01 UTC (permalink / raw)
  To: Marc Zyngier, Pali Rohár
  Cc: Lorenzo Pieralisi, Rob Herring, Krzysztof Wilczyński,
	Bjorn Helgaas, Masami Hiramatsu, linux-pci, linux-arm-kernel,
	linux-kernel

Hi Marc,

On 2021/08/24 1:57, Marc Zyngier wrote:
> On Mon, 23 Aug 2021 16:09:27 +0100,
> Pali Rohár <pali@kernel.org> wrote:
>>
>> + Marc (who originally reported this issue)
>>
>> On Monday 23 August 2021 20:18:20 Kunihiko Hayashi wrote:
>>> The 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 a lock.
>>> Add a lock into each callback 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>
>>
>> Acked-by: Pali Rohár <pali@kernel.org>
>>
>>> ---
>>>   drivers/pci/controller/dwc/pcie-uniphier.c | 15 +++++++++++++++
>>>   1 file changed, 15 insertions(+)
>>>
>>> The previous patch is as follows:
>>> https://lore.kernel.org/linux-pci/1629370566-29984-1-git-send-email-hayashi.kunihiko@socionext.com/
>>>
>>> Changes in the previous patch:
>>> - Change the subject and commit message
>>>
>>> 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);
> 
> This looks extremely suspicious. You clear all the INTX mask bits, and
> only set the one you need. How about the pre-existing bits?

Thanks for pointing out. No need to clear all INTX mask bits.
The pre-existing bits should be preserved.

> 
>>>   	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);
> 
> And by the same token, this second line is totally useless.
> 
> I think masking/unmasking is broken in this driver, locking or not.

Yes, this second line should be removed, too.
I'll fix this bug and add mask locking.

Thank you,

---
Best Regards
Kunihiko Hayashi

^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH] PCI: uniphier: Serialize INTx masking/unmasking
  2021-08-25  0:01     ` Kunihiko Hayashi
@ 2021-08-25  9:07       ` Marc Zyngier
  2021-08-26 10:02         ` Kunihiko Hayashi
  0 siblings, 1 reply; 6+ messages in thread
From: Marc Zyngier @ 2021-08-25  9:07 UTC (permalink / raw)
  To: Kunihiko Hayashi
  Cc: Pali Rohár, Lorenzo Pieralisi, Rob Herring,
	Krzysztof Wilczyński, Bjorn Helgaas, Masami Hiramatsu,
	linux-pci, linux-arm-kernel, linux-kernel

On Wed, 25 Aug 2021 01:01:08 +0100,
Kunihiko Hayashi <hayashi.kunihiko@socionext.com> wrote:
> 
> Hi Marc,
> 
> On 2021/08/24 1:57, Marc Zyngier wrote:
> > On Mon, 23 Aug 2021 16:09:27 +0100,
> > Pali Rohár <pali@kernel.org> wrote:
> >> 
> >> + Marc (who originally reported this issue)
> >> 
> >> On Monday 23 August 2021 20:18:20 Kunihiko Hayashi wrote:
> >>> The 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 a lock.
> >>> Add a lock into each callback 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>
> >> 
> >> Acked-by: Pali Rohár <pali@kernel.org>
> >> 
> >>> ---
> >>>   drivers/pci/controller/dwc/pcie-uniphier.c | 15 +++++++++++++++
> >>>   1 file changed, 15 insertions(+)
> >>> 
> >>> The previous patch is as follows:
> >>> https://lore.kernel.org/linux-pci/1629370566-29984-1-git-send-email-hayashi.kunihiko@socionext.com/
> >>> 
> >>> Changes in the previous patch:
> >>> - Change the subject and commit message
> >>> 
> >>> 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);
> > 
> > This looks extremely suspicious. You clear all the INTX mask bits, and
> > only set the one you need. How about the pre-existing bits?
> 
> Thanks for pointing out. No need to clear all INTX mask bits.
> The pre-existing bits should be preserved.
> 
> > 
> >>>   	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);
> > 
> > And by the same token, this second line is totally useless.
> > 
> > I think masking/unmasking is broken in this driver, locking or not.
> 
> Yes, this second line should be removed, too.

You mean the *first* line, right? The one clearing all the INTx
bits. If you remove the second line, you won't fix anything.

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.

^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH] PCI: uniphier: Serialize INTx masking/unmasking
  2021-08-25  9:07       ` Marc Zyngier
@ 2021-08-26 10:02         ` Kunihiko Hayashi
  0 siblings, 0 replies; 6+ messages in thread
From: Kunihiko Hayashi @ 2021-08-26 10:02 UTC (permalink / raw)
  To: Marc Zyngier
  Cc: Pali Rohár, Lorenzo Pieralisi, Rob Herring,
	Krzysztof Wilczyński, Bjorn Helgaas, Masami Hiramatsu,
	linux-pci, linux-arm-kernel, linux-kernel

Hi Marc,

On 2021/08/25 18:07, Marc Zyngier wrote:
> On Wed, 25 Aug 2021 01:01:08 +0100,
> Kunihiko Hayashi <hayashi.kunihiko@socionext.com> wrote:
>>
>> Hi Marc,
>>
>> On 2021/08/24 1:57, Marc Zyngier wrote:
>>> On Mon, 23 Aug 2021 16:09:27 +0100,
>>> Pali Rohár <pali@kernel.org> wrote:
>>>>
>>>> + Marc (who originally reported this issue)
>>>>
>>>> On Monday 23 August 2021 20:18:20 Kunihiko Hayashi wrote:
>>>>> The 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 a lock.
>>>>> Add a lock into each callback 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>
>>>>
>>>> Acked-by: Pali Rohár <pali@kernel.org>
>>>>
>>>>> ---
>>>>>    drivers/pci/controller/dwc/pcie-uniphier.c | 15 +++++++++++++++
>>>>>    1 file changed, 15 insertions(+)
>>>>>
>>>>> The previous patch is as follows:
>>>>> https://lore.kernel.org/linux-pci/1629370566-29984-1-git-send-email-hayashi.kunihiko@socionext.com/
>>>>>
>>>>> Changes in the previous patch:
>>>>> - Change the subject and commit message
>>>>>
>>>>> 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);
>>>
>>> This looks extremely suspicious. You clear all the INTX mask bits, and
>>> only set the one you need. How about the pre-existing bits?
>>
>> Thanks for pointing out. No need to clear all INTX mask bits.
>> The pre-existing bits should be preserved.
>>
>>>
>>>>>    	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);
>>>
>>> And by the same token, this second line is totally useless.
>>>
>>> I think masking/unmasking is broken in this driver, locking or not.
>>
>> Yes, this second line should be removed, too.
> 
> You mean the *first* line, right? The one clearing all the INTx
> bits. If you remove the second line, you won't fix anything.
This is ambiguous. I mean that I will remove the following line:

     	val &= ~PCL_RCV_INTX_ALL_MASK;

So the fixed unmasking code is as follows.

     	val = readl(priv->base + PCL_RCV_INTX);
     	val &= ~BIT(irqd_to_hwirq(d) + PCL_RCV_INTX_STATUS_SHIFT);
     	writel(val, priv->base + PCL_RCV_INTX);

Thank you,

---
Best Regards
Kunihiko Hayashi

^ permalink raw reply	[flat|nested] 6+ messages in thread

end of thread, other threads:[~2021-08-26 10:02 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-08-23 11:18 [PATCH] PCI: uniphier: Serialize INTx masking/unmasking Kunihiko Hayashi
2021-08-23 15:09 ` Pali Rohár
2021-08-23 16:57   ` Marc Zyngier
2021-08-25  0:01     ` Kunihiko Hayashi
2021-08-25  9:07       ` Marc Zyngier
2021-08-26 10:02         ` Kunihiko Hayashi

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