Messages in this thread | ![/](/images/icornerl.gif) | | Subject | Re: [PATCH] PCI: uniphier: Serialize INTx masking/unmasking | From | Kunihiko Hayashi <> | Date | Wed, 25 Aug 2021 09:01:08 +0900 |
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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
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