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From: Logan Gunthorpe <logang@deltatee.com>
To: James Sewart <jamessewart@arista.com>, linux-pci@vger.kernel.org
Cc: Dmitry Safonov <dima@arista.com>,
	Dmitry Safonov <0x7f454c46@gmail.com>,
	iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
	Alex Williamson <alex.williamson@redhat.com>,
	Bjorn Helgaas <helgaas@kernel.org>
Subject: Re: [PATCH v3 1/2] PCI: Add parameter nr_devfns to pci_add_dma_alias
Date: Wed, 27 Nov 2019 10:38:42 -0700	[thread overview]
Message-ID: <9c54c5dd-702c-a19b-38ba-55ab73b24729@deltatee.com> (raw)
In-Reply-To: <547214A9-9FD0-4DD5-80E1-1F5A467A0913@arista.com>



On 2019-11-27 6:27 a.m., James Sewart wrote:
>   * This helper encodes an 8-bit devfn as a bit number in dma_alias_mask
>   * which is used to program permissible bus-devfn source addresses for DMA
> @@ -5873,8 +5874,12 @@ int pci_set_vga_state(struct pci_dev *dev, bool decode,
>   * cannot be left as a userspace activity).  DMA aliases should therefore
>   * be configured via quirks, such as the PCI fixup header quirk.
>   */
> -void pci_add_dma_alias(struct pci_dev *dev, u8 devfn)
> +void pci_add_dma_alias(struct pci_dev *dev, u8 devfn_from, int nr_devfns)
>  {
> +	int devfn_to = devfn_from + nr_devfns - 1;
> +
> +	BUG_ON(nr_devfns < 1);

Why not just make nr_devfns unsigned and do nothing if it's zero? It
might also be worth checking that nr_devfns + devfn_from is less than
U8_MAX... But I'd probably avoid the BUG_ON and just truncate it.

Logan
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  parent reply	other threads:[~2019-11-27 17:38 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-24 12:52 [PATCH] Ensure pci transactions coming from PLX NTB are handled when IOMMU is turned on James Sewart via iommu
2019-11-05 12:17 ` James Sewart via iommu
2019-11-20 17:48   ` Dmitry Safonov
2019-11-20 19:30     ` Logan Gunthorpe
2019-11-20 19:49       ` Bjorn Helgaas
2019-11-20 19:32     ` Bjorn Helgaas
2019-11-26 17:03       ` [PATCH v2] PCI: Add DMA alias quirk for PLX PEX NTB James Sewart via iommu
2019-11-26 17:06         ` Logan Gunthorpe
2019-11-26 17:36           ` [PATCH v3 1/2] PCI: Add helper pci_add_dma_alias_range James Sewart via iommu
2019-11-26 17:37             ` [PATCH v3 2/2] PCI: Add DMA alias quirk for PLX PEX NTB James Sewart via iommu
2019-11-26 17:38         ` [PATCH v2] " Christoph Hellwig
2019-11-27 13:27           ` [PATCH v3 1/2] PCI: Add parameter nr_devfns to pci_add_dma_alias James Sewart via iommu
2019-11-27 13:28             ` [PATCH v3 2/2] PCI: Add DMA alias quirk for PLX PEX NTB James Sewart via iommu
2019-11-27 17:38             ` Logan Gunthorpe [this message]
2019-11-29 12:49               ` [PATCH v4 1/2] PCI: Add parameter nr_devfns to pci_add_dma_alias James Sewart via iommu
2019-11-29 12:49                 ` [PATCH v4 2/2] PCI: Add DMA alias quirk for PLX PEX NTB James Sewart via iommu
2019-11-29 16:50                 ` [PATCH v4 1/2] PCI: Add parameter nr_devfns to pci_add_dma_alias Logan Gunthorpe
2019-11-29 17:19                   ` James Sewart via iommu
2019-11-29 17:26                     ` Logan Gunthorpe
2019-11-29 17:56                       ` [PATCH v5 1/3] PCI: Fix off by one in dma_alias_mask allocation size James Sewart via iommu
2019-11-29 17:56                         ` [PATCH v5 2/3] PCI: Add parameter nr_devfns to pci_add_dma_alias James Sewart via iommu
2019-11-29 17:57                           ` [PATCH v5 3/3] PCI: Add DMA alias quirk for PLX PEX NTB James Sewart via iommu
2019-12-02 17:03                           ` [PATCH v5 2/3] PCI: Add parameter nr_devfns to pci_add_dma_alias Christoph Hellwig
2019-11-29 17:58                         ` [PATCH v5 1/3] PCI: Fix off by one in dma_alias_mask allocation size Logan Gunthorpe
2019-12-02 17:03                         ` Christoph Hellwig

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