> -----Original Message----- > From: Logan Gunthorpe <logang@xxxxxxxxxxxx> > Sent: Wednesday, June 3, 2020 5:48 PM > > > > On 2020-06-03 5:44 a.m., Piotr Stankiewicz wrote: > > When debugging an issue where I was asking the PCI machinery to enable a > > set of MSI-X vectors, without falling back on MSI, I ran across a > > behaviour which seems odd. The pci_alloc_irq_vectors_affinity() will > > always return -ENOSPC on failure, when allocating MSI-X vectors only, > > whereas with MSI fallback it will forward any error returned by > > __pci_enable_msi_range(). This is a confusing behaviour, so have the > > pci_alloc_irq_vectors_affinity() forward the error code from > > __pci_enable_msix_range() when appropriate. > > > > Signed-off-by: Piotr Stankiewicz <piotr.stankiewicz@xxxxxxxxx> > > Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxx> > > --- > > drivers/pci/msi.c | 5 +++-- > > 1 file changed, 3 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c > > index 6b43a5455c7a..443cc324b196 100644 > > --- a/drivers/pci/msi.c > > +++ b/drivers/pci/msi.c > > @@ -1231,8 +1231,9 @@ int pci_alloc_irq_vectors_affinity(struct pci_dev > *dev, unsigned int min_vecs, > > } > > } > > > > - if (msix_vecs == -ENOSPC) > > - return -ENOSPC; > > + if (msix_vecs == -ENOSPC || > > + (flags & (PCI_IRQ_MSI | PCI_IRQ_MSIX)) == PCI_IRQ_MSIX) > > + return msix_vecs; > > return msi_vecs; > > } > > EXPORT_SYMBOL(pci_alloc_irq_vectors_affinity); > > > > It occurs to me that we could clean this function up a bit more... I > don't see any need to have two variables for msi_vecs and msix_vecs and > then have a complicated bit of logic at the end to decide which to return. > > Why not instead just have one variable which is set by > __pci_enable_msix_range(), then __pci_enable_msi_range(), then returned > if they both fail? > That wouldn't preserve the original bit of logic where -ENOSPC is returned any time __pci_enable_msix_range() fails with -ENOSPC, irrespective of whether MSI fallback was requested. Though I don't know if that is desired behaviour. BR, Piotr
