[PATCH v2 01/15] PCI/MSI: Forward MSI-X vector enable error code in pci_alloc_irq_vectors_affinity()

From: Piotr Stankiewicz <piotr.stankiewicz@intel.com>
To: Bjorn Helgaas <bhelgaas@google.com>, linux-pci@vger.kernel.org
Cc: Piotr Stankiewicz <piotr.stankiewicz@intel.com>,
	Andy Shevchenko <andriy.shevchenko@intel.com>,
	Logan Gunthorpe <logang@deltatee.com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
	Jian-Hong Pan <jian-hong@endlessm.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	linux-kernel@vger.kernel.org
Subject: [PATCH v2 01/15] PCI/MSI: Forward MSI-X vector enable error code in pci_alloc_irq_vectors_affinity()
Date: Wed,  3 Jun 2020 13:44:24 +0200	[thread overview]
Message-ID: <20200603114425.12734-1-piotr.stankiewicz@intel.com> (raw)
In-Reply-To: <20200603114212.12525-1-piotr.stankiewicz@intel.com>

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@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
---
 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);
-- 
2.17.2

