From: Logan Gunthorpe <logang@deltatee.com>
To: "Stankiewicz, Piotr" <piotr.stankiewicz@intel.com>,
Bjorn Helgaas <bhelgaas@google.com>,
"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>
Cc: "Shevchenko, Andriy" <andriy.shevchenko@intel.com>,
"Wysocki, Rafael J" <rafael.j.wysocki@intel.com>,
Jian-Hong Pan <jian-hong@endlessm.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 01/15] PCI/MSI: Forward MSI-X vector enable error code in pci_alloc_irq_vectors_affinity()
Date: Wed, 3 Jun 2020 10:22:16 -0600 [thread overview]
Message-ID: <6bfeb14e-b2b7-3843-f417-1a2858859869@deltatee.com> (raw)
In-Reply-To: <CY4PR11MB152819A4C01C524E06A48EBFF9880@CY4PR11MB1528.namprd11.prod.outlook.com>
On 2020-06-03 10:04 a.m., Stankiewicz, Piotr wrote:
>> -----Original Message-----
>> From: Logan Gunthorpe <logang@deltatee.com>
>> 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@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);
>>>
>>
>> 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.
That does look very odd, but ok... Then, couldn't we just set msi_vecs
to msix_vecs after calling __pci_enable_msix_range() such that if
__pci_enable_msi_range() doesn't get called we will return the same
error without needing the messy second conditional?
Logan
next prev parent reply other threads:[~2020-06-03 16:22 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20200603114212.12525-1-piotr.stankiewicz@intel.com>
2020-06-03 11:44 ` [PATCH v2 01/15] PCI/MSI: Forward MSI-X vector enable error code in pci_alloc_irq_vectors_affinity() Piotr Stankiewicz
2020-06-03 15:48 ` Logan Gunthorpe
2020-06-03 16:04 ` Stankiewicz, Piotr
2020-06-03 16:22 ` Logan Gunthorpe [this message]
2020-06-09 9:27 ` Stankiewicz, Piotr
2020-06-03 11:46 ` [PATCH v2 03/15] PCI: Use PCI_IRQ_MSI_TYPES where appropriate Piotr Stankiewicz
2020-06-03 11:47 ` [PATCH v2 04/15] ahci: " Piotr Stankiewicz
2020-06-03 11:47 ` [PATCH v2 05/15] crypto: inside-secure - " Piotr Stankiewicz
2020-06-03 13:30 ` kernel test robot
2020-06-03 11:47 ` [PATCH v2 06/15] dmaengine: dw-edma: " Piotr Stankiewicz
2020-06-03 11:54 ` Gustavo Pimentel
2020-06-03 11:47 ` [PATCH v2 07/15] drm/amdgpu: " Piotr Stankiewicz
2020-06-03 13:43 ` Alex Deucher
2020-06-03 11:48 ` [PATCH v2 08/15] IB/qib: " Piotr Stankiewicz
2020-06-03 11:48 ` [PATCH v2 09/15] media: ddbridge: " Piotr Stankiewicz
2020-06-03 11:48 ` [PATCH v2 10/15] vmw_vmci: Use PCI_IRQ_ALL_TYPES " Piotr Stankiewicz
2020-06-03 11:49 ` [PATCH v2 11/15] mmc: sdhci: Use PCI_IRQ_MSI_TYPES " Piotr Stankiewicz
2020-06-03 11:49 ` [PATCH v2 12/15] amd-xgbe: " Piotr Stankiewicz
2020-06-03 11:49 ` [PATCH v2 13/15] aquantia: atlantic: Use PCI_IRQ_ALL_TYPES " Piotr Stankiewicz
2020-06-03 11:49 ` [PATCH v2 14/15] net: hns3: Use PCI_IRQ_MSI_TYPES " Piotr Stankiewicz
2020-06-03 11:50 ` [PATCH v2 15/15] scsi: Use PCI_IRQ_MSI_TYPES and PCI_IRQ_ALL_TYPES " Piotr Stankiewicz
2020-06-09 9:11 ` [PATCH v3 00/15] Forward MSI-X vector enable error code in pci_alloc_irq_vectors_affinity() Piotr Stankiewicz
2020-06-09 9:14 ` [PATCH v3 01/15] PCI/MSI: " Piotr Stankiewicz
2020-06-09 15:49 ` Logan Gunthorpe
2020-06-09 15:49 ` Christoph Hellwig
2020-06-09 9:16 ` [PATCH v3 03/15] PCI: Use PCI_IRQ_MSI_TYPES where appropriate Piotr Stankiewicz
2020-06-09 15:51 ` Christoph Hellwig
2020-06-09 16:31 ` Stankiewicz, Piotr
2020-06-09 16:35 ` Logan Gunthorpe
2020-06-09 9:17 ` [PATCH v3 04/15] ahci: " Piotr Stankiewicz
2020-06-09 9:17 ` [PATCH v3 05/15] crypto: inside-secure - " Piotr Stankiewicz
2020-06-09 9:17 ` [PATCH v3 06/15] dmaengine: dw-edma: " Piotr Stankiewicz
2020-06-09 10:01 ` Andy Shevchenko
2020-06-09 9:18 ` [PATCH v3 07/15] drm/amdgpu: " Piotr Stankiewicz
2020-06-09 20:23 ` Alex Deucher
2020-06-16 7:49 ` Stankiewicz, Piotr
2020-06-16 8:42 ` [PATCH] drm/amdgpu: Simplify IRQ vector request logic Piotr Stankiewicz
2020-06-09 9:18 ` [PATCH v3 08/15] IB/qib: Use PCI_IRQ_MSI_TYPES where appropriate Piotr Stankiewicz
2020-06-11 13:17 ` Ruhl, Michael J
2020-06-09 9:18 ` [PATCH v3 09/15] media: ddbridge: " Piotr Stankiewicz
2020-06-09 9:19 ` [PATCH v3 10/15] vmw_vmci: Use PCI_IRQ_ALL_TYPES " Piotr Stankiewicz
2020-06-09 9:19 ` [PATCH v3 11/15] mmc: sdhci: Use PCI_IRQ_MSI_TYPES " Piotr Stankiewicz
2020-06-09 9:19 ` [PATCH v3 12/15] amd-xgbe: " Piotr Stankiewicz
2020-06-09 9:19 ` [PATCH v3 13/15] aquantia: atlantic: Use PCI_IRQ_ALL_TYPES " Piotr Stankiewicz
2020-06-09 9:20 ` [PATCH v3 14/15] net: hns3: Use PCI_IRQ_MSI_TYPES " Piotr Stankiewicz
2020-06-09 9:20 ` [PATCH v3 15/15] scsi: Use PCI_IRQ_MSI_TYPES and PCI_IRQ_ALL_TYPES " Piotr Stankiewicz
2020-06-09 16:22 ` [PATCH v3 02/15] PCI: Add macro for message signalled interrupt types Piotr Stankiewicz
2020-06-10 7:08 ` Christoph Hellwig
2020-06-16 7:39 ` Stankiewicz, Piotr
2020-06-16 7:33 ` [PATCH v4] PCI/MSI: Forward MSI-X vector enable error code in pci_alloc_irq_vectors_affinity() Piotr Stankiewicz
2020-06-30 22:04 ` Bjorn Helgaas
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