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Re: [Qemu-devel] [PATCH] vfio/pci: replace 1 with PCI_CAP_LIST_NEXT to m
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH] vfio/pci: replace 1 with PCI_CAP_LIST_NEXT to make code self-explain |
Date: |
Wed, 16 Mar 2016 12:52:52 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 |
On 16/03/2016 12:27, Michael Tokarev wrote:
>> > for (tmp = pdev->config[PCI_CAPABILITY_LIST]; tmp;
>> > - tmp = pdev->config[tmp + 1]) {
>> > + tmp = pdev->config[tmp + PCI_CAP_LIST_NEXT]) {
>> > - next = pdev->config[pos + 1];
>> > + next = pdev->config[pos + PCI_CAP_LIST_NEXT];
> Hmm. I'm not sure the new version is better, to me "+1" reads
> easier than the new symbolic constant variant.
>
> If it were something like pdev->config[PCI_CAP_LIST_NEXT], that'd be
> nice, but not "pos + PCI_CAP_LIST_NEXT".
>
> But again, I'm not pci config space expert and don't understand
> the basics :)
Each capability is a node of a linked list, and the position of the next
capability is at offset 1 inside the capability (here it is at offset 1
from the tmp or pos base). I think the patch is an improvement.
Paolo