Re: [PATCH] x86 PCI: Do not use interrupt links for devices using MSI-X

Rafael J. Wysocki
2009-01-05T13:50:53Z

On Monday 05 January 2009, Ingo Molnar wrote:
>
> * Rafael J. Wysocki <rjw@sisk.pl> wrote:
>
> > From: Rafael J. Wysocki <rjw@sisk.pl>
> >
> > pcibios_enable_device() and pcibios_disable_device() don't handle
> > IRQs for devices that have MSI enabled and it should tread the
>
> s/tread/treat

Ah, thanks.

> > devices with MSI-X enabled in the same way.
> >
> > Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
> > ---
> > arch/x86/pci/common.c | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
>
> looks good - Jesse, what do you think?
>
> Rafael, i'm curious is this in response to some regression/bug? Did some
> box or driver get confused by us enabling/disabling the GSI? Some IRQ
> flood perhaps?

Well, I don't have any MSI-X capable boxes around. :-)

I was just reviewing the code and spotted this.

> btw., there's a small observation:
>
> > + if (!dev->msi_enabled && !dev->msix_enabled)
>
> maybe a "pci_has_gsi_irq()" wrapper would make these checks cleaner and
> would make things more robust, should there be any new IRQ delivery method
> be introduced in the future?

Well, perhaps something like the patch below?

Thanks,
Rafael

---
Subject: x86 PCI: Do not use interrupt links for devices using MSI-X (rev. 2)
From: Rafael J. Wysocki <rjw@sisk.pl>

pcibios_enable_device() and pcibios_disable_device() don't handle
IRQs for devices that have MSI enabled and it should treat the
devices with MSI-X enabled in the same way.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
---
arch/x86/pci/common.c | 4 ++--
include/linux/pci.h | 9 +++++++++
2 files changed, 11 insertions(+), 2 deletions(-)

Index: linux-2.6/arch/x86/pci/common.c
===================================================================
--- linux-2.6.orig/arch/x86/pci/common.c
+++ linux-2.6/arch/x86/pci/common.c
@@ -551,14 +551,14 @@ int pcibios_enable_device(struct pci_dev
if ((err = pci_enable_resources(dev, mask)) < 0)
return err;

- if (!dev->msi_enabled)
+ if (!pci_msi_enabled(dev))
return pcibios_enable_irq(dev);
return 0;
}

void pcibios_disable_device (struct pci_dev *dev)
{
- if (!dev->msi_enabled && pcibios_disable_irq)
+ if (!pci_msi_enabled(dev) && pcibios_disable_irq)
pcibios_disable_irq(dev);
}

Index: linux-2.6/include/linux/pci.h
===================================================================
--- linux-2.6.orig/include/linux/pci.h
+++ linux-2.6/include/linux/pci.h
@@ -274,6 +274,15 @@ static inline void pci_add_saved_cap(str
hlist_add_head(&new_cap->next, &pci_dev->saved_cap_space);
}

+#ifdef CONFIG_PCI_MSI
+static inline bool pci_msi_enabled(struct pci_dev *pci_dev)
+{
+ return dev->msi_enabled || dev->msix_enabled;
+}
+#else
+static inline bool pci_msi_enabled(struct pci_dev *pci_dev) { return false; }
+#endif
+
/*
* For PCI devices, the region numbers are assigned this way:
*