Re: [patch 29/37] PCI/MSI: Use __msi_get_virq() in pci_get_vector()

Thomas Gleixner
2021-11-28T21:02:35Z

On Sun, Nov 28 2021 at 19:37, Marc Zyngier wrote:
> On Sat, 27 Nov 2021 01:22:03 +0000,
> Thomas Gleixner <tglx@linutronix.de> wrote:
>
> I worked around it with the hack below, but I doubt this is the real
> thing. portdrv_core.c does complicated things, and I don't completely
> understand its logic.
>
> M.
>
> diff --git a/drivers/pci/msi/msi.c b/drivers/pci/msi/msi.c
> index 1f72bc734226..b15278a5fb4b 100644
> --- a/drivers/pci/msi/msi.c
> +++ b/drivers/pci/msi/msi.c
> @@ -1092,8 +1092,9 @@ int pci_irq_vector(struct pci_dev *dev, unsigned int nr)
> int irq = __msi_get_virq(&dev->dev, nr);
>
> switch (irq) {
> - case -ENODEV: return !nr ? dev->irq : -EINVAL;
> - case -ENOENT: return -EINVAL;
> + case -ENOENT:
> + case -ENODEV:
> + return !nr ? dev->irq : -EINVAL;

Hrm. ENODEV is returned when dev->msi.data == NULL, ENOENT when there is
no MSI entry. But yes, that goes south when the device tried to enable
MSI[X} and then ended up with INTx. It still has dev->msi.data, which
causes it to return -ENOENT, which makes the above go belly up.

Moo, what was I thinking?

Thanks,

tglx
---
--- a/drivers/pci/msi/msi.c
+++ b/drivers/pci/msi/msi.c
@@ -1032,13 +1032,13 @@ EXPORT_SYMBOL(pci_free_irq_vectors);
*/
int pci_irq_vector(struct pci_dev *dev, unsigned int nr)
{
- int irq = __msi_get_virq(&dev->dev, nr);
+ unsigned int irq;

- switch (irq) {
- case -ENODEV: return !nr ? dev->irq : -EINVAL;
- case -ENOENT: return -EINVAL;
- }
- return irq;
+ if (!dev->msi_enabled && !dev->msix_enabled)
+ return !nr ? dev->irq : -EINVAL;
+
+ irq = msi_get_virq(&dev->dev, nr);
+ return irq ? irq : -EINVAL;
}
EXPORT_SYMBOL(pci_irq_vector);

--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -169,21 +169,7 @@ static inline bool msi_device_has_proper
}
#endif

-int __msi_get_virq(struct device *dev, unsigned int index);
-
-/**
- * msi_get_virq - Return Linux interrupt number of a MSI interrupt
- * @dev: Device to operate on
- * @index: MSI interrupt index to look for (0-based)
- *
- * Return: The Linux interrupt number on success (> 0), 0 if not found
- */
-static inline unsigned int msi_get_virq(struct device *dev, unsigned int index)
-{
- int ret = __msi_get_virq(dev, index);
-
- return ret < 0 ? 0 : ret;
-}
+unsigned int msi_get_virq(struct device *dev, unsigned int index);

/* Helpers to hide struct msi_desc implementation details */
#define msi_desc_to_dev(desc) ((desc)->dev)
--- a/kernel/irq/msi.c
+++ b/kernel/irq/msi.c
@@ -119,21 +119,19 @@ int msi_setup_device_data(struct device
}

/**
- * __msi_get_virq - Return Linux interrupt number of a MSI interrupt
+ * msi_get_virq - Return Linux interrupt number of a MSI interrupt
* @dev: Device to operate on
* @index: MSI interrupt index to look for (0-based)
*
- * Return: The Linux interrupt number on success (> 0)
- * -ENODEV when the device is not using MSI
- * -ENOENT if no such entry exists
+ * Return: The Linux interrupt number on success (> 0), 0 if not found
*/
-int __msi_get_virq(struct device *dev, unsigned int index)
+unsigned int msi_get_virq(struct device *dev, unsigned int index)
{
struct msi_desc *desc;
bool pcimsi;

if (!dev->msi.data)
- return -ENODEV;
+ return 0;

pcimsi = msi_device_has_property(dev, MSI_PROP_PCI_MSI);

@@ -152,9 +150,9 @@ int __msi_get_virq(struct device *dev, u
if (desc->msi_index == index)
return desc->irq;
}
- return -ENOENT;
+ return 0;
}
-EXPORT_SYMBOL_GPL(__msi_get_virq);
+EXPORT_SYMBOL_GPL(msi_get_virq);

#ifdef CONFIG_SYSFS
static ssize_t msi_mode_show(struct device *dev, struct device_attribute *attr,