From: Paolo Bonzini <pbonzini@redhat.com>
To: Michael Tokarev <mjt@tls.msk.ru>,
Wei Yang <richard.weiyang@gmail.com>,
alex.williamson@redhat.com
Cc: qemu-trivial@nongnu.org, qemu-devel@nongnu.org
Subject: Re: [Qemu-trivial] [PATCH] vfio/pci: replace 1 with PCI_CAP_LIST_NEXT to make code self-explain
Date: Wed, 16 Mar 2016 12:52:52 +0100 [thread overview]
Message-ID: <56E94914.1040803@redhat.com> (raw)
In-Reply-To: <56E9433C.1040503@msgid.tls.msk.ru>
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
WARNING: multiple messages have this Message-ID (diff)
From: Paolo Bonzini <pbonzini@redhat.com>
To: Michael Tokarev <mjt@tls.msk.ru>,
Wei Yang <richard.weiyang@gmail.com>,
alex.williamson@redhat.com
Cc: qemu-trivial@nongnu.org, qemu-devel@nongnu.org
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 [thread overview]
Message-ID: <56E94914.1040803@redhat.com> (raw)
In-Reply-To: <56E9433C.1040503@msgid.tls.msk.ru>
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
next prev parent reply other threads:[~2016-03-16 11:53 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-11 0:54 [Qemu-trivial] [PATCH] vfio/pci: replace 1 with PCI_CAP_LIST_NEXT to make code self-explain Wei Yang
2016-02-11 0:54 ` [Qemu-devel] " Wei Yang
2016-03-16 11:27 ` [Qemu-trivial] " Michael Tokarev
2016-03-16 11:27 ` [Qemu-devel] " Michael Tokarev
2016-03-16 11:52 ` Paolo Bonzini [this message]
2016-03-16 11:52 ` Paolo Bonzini
2016-03-17 15:01 ` [Qemu-trivial] " Wei Yang
2016-03-17 15:01 ` [Qemu-devel] " Wei Yang
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