From: Matthew Wilcox <matthew@wil.cx>
To: kernel-janitors@vger.kernel.org
Subject: Re: [KJ] question about pci_dev_put
Date: Thu, 18 May 2006 02:47:53 +0000 [thread overview]
Message-ID: <20060518024753.GH1604@parisc-linux.org> (raw)
In-Reply-To: <446BAEC6.9080907@yahoo.fr>
[-- Attachment #1: Type: text/plain, Size: 1905 bytes --]
On Wed, May 17, 2006 at 06:20:16PM -0700, Nishanth Aravamudan wrote:
> > if ((dev = pci_get_device(PCI_VENDOR_ID_VIA,
> > PCI_DEVICE_ID_VIA_82C586_2,
> > NULL))) {
> > dev->irq = 10;
> > pci_write_config_byte(dev, PCI_INTERRUPT_LINE, 10);
> > pci_dev_put(dev);
> > }
> >
> > if ((dev = pci_get_device(PCI_VENDOR_ID_VIA,
> > PCI_DEVICE_ID_VIA_82C586_2, dev))) {
> > dev->irq = 11;
> > pci_write_config_byte(dev, PCI_INTERRUPT_LINE, 11);
> > pci_dev_put(dev);
> > }
> >
> > So, if I don't mistake, this code is buggy, the counter is decremented
> > twice in the second if.
> > One in the pci_get_device and one in pci_dev_put. I'm on the right way ?
>
> /me knows nothing about the PCI space, but looking at the comments for
> pci_get_device() and tracing what pci_dev_put() does, it seems like you
> are right.
>
> It seems like the correct method is to remove the pci_dev_put(dev); from
> the first if above and change the second one to
>
> if ((dev = pci_get_device(PCI_VENDOR_ID_VIA,
> PCI_DEVICE_ID_VIA_82C586_2, dev))) {
> dev->irq = 11;
> pci_write_config_byte(dev, PCI_INTERRUPT_LINE, 11);
> pci_dev_put(dev);
> } else
> pci_dev_put(dev);
>
> In the if case, pci_get_device will call pci_dev_put() on the old
> dev before returning the next dev. In the else case, there are no more
> devices, so we drop the refcount with an explicit pci_dev_put(). In both
> cases, we drop the refcount on the old dev.
>
> Does that seem right?
No. pci_get_device unconditionally does pci_dev_put(). So if should
just be:
if ((dev = pci_get_device(PCI_VENDOR_ID_VIA,
PCI_DEVICE_ID_VIA_82C586_2, dev))) {
dev->irq = 11;
pci_write_config_byte(dev, PCI_INTERRUPT_LINE, 11);
pci_dev_put(dev);
}
[-- Attachment #2: Type: text/plain, Size: 168 bytes --]
_______________________________________________
Kernel-janitors mailing list
Kernel-janitors@lists.osdl.org
https://lists.osdl.org/mailman/listinfo/kernel-janitors
next prev parent reply other threads:[~2006-05-18 2:47 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-05-17 23:16 [KJ] question about pci_dev_put trem
2006-05-18 1:20 ` Nishanth Aravamudan
2006-05-18 1:43 ` Mark Hollomon
2006-05-18 2:00 ` Nishanth Aravamudan
2006-05-18 2:47 ` Matthew Wilcox [this message]
2006-05-18 3:39 ` Nishanth Aravamudan
2006-05-18 11:59 ` Matthew Wilcox
2006-05-18 12:57 ` Mark Hollomon
2006-05-18 17:36 ` Greg KH
2006-05-18 17:37 ` Greg KH
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20060518024753.GH1604@parisc-linux.org \
--to=matthew@wil.cx \
--cc=kernel-janitors@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.