From mboxrd@z Thu Jan 1 00:00:00 1970 From: ming.lei@redhat.com (Ming Lei) Date: Thu, 3 Jan 2019 09:31:06 +0800 Subject: [PATCH] PCI/MSI: preference to returning -ENOSPC from pci_alloc_irq_vectors_affinity Message-ID: <20190103013106.26452-1-ming.lei@redhat.com> The API of pci_alloc_irq_vectors_affinity() requires to return -ENOSPC if fewer than @min_vecs interrupt vectors are available for @dev. However, if a device supports MSI-X but not MSI and a caller requests @min_vecs that can't be satisfied by MSI-X, we previously returned -EINVAL (from the failed attempt to enable MSI), not -ENOSPC. Users of pci_alloc_irq_vectors_affinity() may try to reduce irq vectors and allocate vectors again in case that -ENOSPC is returned, such as NVMe, so we need to respect the current interface and give preference to -ENOSPC. Especially the min/max vecs doesn't work correctly when using the irq_affinity nr_sets because rebalancing the set counts is driver specific. To get around that, drivers using nr_sets have to set min and max to the same value and handle the "reduce and try again". Cc: Jens Axboe Cc: Keith Busch Cc: linux-nvme at lists.infradead.org Cc: Bjorn Helgaas Cc: Christoph Hellwig Signed-off-by: Ming Lei --- drivers/pci/msi.c | 22 +++++++++++++--------- 1 file changed, 13 insertions(+), 9 deletions(-) diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c index 7a1c8a09efa5..4c0b47867258 100644 --- a/drivers/pci/msi.c +++ b/drivers/pci/msi.c @@ -1168,7 +1168,8 @@ int pci_alloc_irq_vectors_affinity(struct pci_dev *dev, unsigned int min_vecs, const struct irq_affinity *affd) { static const struct irq_affinity msi_default_affd; - int vecs = -ENOSPC; + int msix_vecs = -ENOSPC; + int msi_vecs = -ENOSPC; if (flags & PCI_IRQ_AFFINITY) { if (!affd) @@ -1179,16 +1180,17 @@ int pci_alloc_irq_vectors_affinity(struct pci_dev *dev, unsigned int min_vecs, } if (flags & PCI_IRQ_MSIX) { - vecs = __pci_enable_msix_range(dev, NULL, min_vecs, max_vecs, - affd); - if (vecs > 0) - return vecs; + msix_vecs = __pci_enable_msix_range(dev, NULL, min_vecs, + max_vecs, affd); + if (msix_vecs > 0) + return msix_vecs; } if (flags & PCI_IRQ_MSI) { - vecs = __pci_enable_msi_range(dev, min_vecs, max_vecs, affd); - if (vecs > 0) - return vecs; + msi_vecs = __pci_enable_msi_range(dev, min_vecs, max_vecs, + affd); + if (msi_vecs > 0) + return msi_vecs; } /* use legacy irq if allowed */ @@ -1199,7 +1201,9 @@ int pci_alloc_irq_vectors_affinity(struct pci_dev *dev, unsigned int min_vecs, } } - return vecs; + if (msix_vecs == -ENOSPC) + return -ENOSPC; + return msi_vecs; } EXPORT_SYMBOL(pci_alloc_irq_vectors_affinity); -- 2.9.5