Re: [PATCH] PCI:MSI Return -ENOSPC when requested vectors is not enough
From: Bjorn Helgaas <helgaas@kernel.org>
Date: 2017-02-10 22:16:17
Also in:
linux-arm-kernel, linux-pci
On Thu, Dec 01, 2016 at 10:15:04AM +0800, Dennis Chen wrote:
The __pci_enable_msi_range() should return -ENOSPC instead of -EINVAL
when the device doesn't have enough vectors as required, just as the
MSI-X vector allocator does in __pci_enable_msix_range(). Otherwise,
some drivers depending on that return value will probably fallback to
the legacy interrupt directly, for example, in commit 17a51f12cfbd2814
("ahci: only try to use multi-MSI mode if there is more than 1 port"), the
ahci driver will fallback to single MSI mode only when the return value
is -ENOSPC in case of required vectors is not enough, else the driver will
use legacy interrupt which has been observed on a x86 box with 6-port SATA
controller.
With this patch, when a MSI-capable device doesn't have enough MSI
vectors as requested, it will fallback to single MSI mode while not
legacy interrupt.
Signed-off-by: Dennis Chen <redacted>
Cc: Tejun Heo <tj@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Tom Long Nguyen <redacted>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Marc Zyngier <redacted>
Cc: Lorenzo Pieralisi <redacted>
Cc: Steve Capper <redacted>
Cc: linux-ide@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.orgApplied to pci/msi for v4.11, thanks, Dennis!
quoted hunk ↗ jump to hunk
--- drivers/pci/msi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c index ad70507..da37113 100644 --- a/drivers/pci/msi.c +++ b/drivers/pci/msi.c@@ -1084,7 +1084,7 @@ static int __pci_enable_msi_range(struct pci_dev *dev, int minvec, int maxvec, if (nvec < 0) return nvec; if (nvec < minvec) - return -EINVAL; + return -ENOSPC; if (nvec > maxvec) nvec = maxvec;-- 2.7.4 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel