linux-kernel - [PATCH 02/15] PCI/MSI: forward MSIx vector enable error code in pci_alloc_irq_vectors

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Message-Id: <20200602091953.31739-1-piotr.stankiewicz@intel.com>
Date:   Tue,  2 Jun 2020 11:19:53 +0200
From:   Piotr Stankiewicz <piotr.stankiewicz@...el.com>
To:     Bjorn Helgaas <bhelgaas@...gle.com>
Cc:     linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        Piotr Stankiewicz <piotr.stankiewicz@...el.com>
Subject: [PATCH 02/15] PCI/MSI: forward MSIx vector enable error code in pci_alloc_irq_vectors_affinity

When debugging an issue where I was asking the PCI machinery to enable a
set of MSIx 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 MSIx 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@...el.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@...el.com>
---
 drivers/pci/msi.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 6b43a5455c7a..9db9ce5dddb3 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -1231,8 +1231,8 @@ 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_TYPES) == PCI_IRQ_MSIX)
+		return msix_vecs;
 	return msi_vecs;
 }
 EXPORT_SYMBOL(pci_alloc_irq_vectors_affinity);
-- 
2.17.2