All of lore.kernel.org
 help / color / mirror / Atom feed
From: "Oliver O'Halloran" <oohall@gmail.com>
To: Tyrel Datwyler <tyreld@linux.ibm.com>
Cc: Xu Wang <vulab@iscas.ac.cn>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Bjorn Helgaas <bhelgaas@google.com>,
	linux-pci <linux-pci@vger.kernel.org>,
	linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] pci/hotplug/pnv-php: Remove probable double put
Date: Wed, 8 Sep 2021 09:17:49 +1000	[thread overview]
Message-ID: <CAOSf1CGEAhXzqEU_-F39um8ri98r1Ww+AtsXJqZu4U7a_ODi9w@mail.gmail.com> (raw)
In-Reply-To: <0fa7ddfa-cd65-583e-a83f-4cbcd4e7337f@linux.ibm.com>

On Wed, Sep 8, 2021 at 8:02 AM Tyrel Datwyler <tyreld@linux.ibm.com> wrote:
>
> On 9/7/21 1:59 AM, Xu Wang wrote:
> > Device node iterators put the previous value of the index variable,
> > so an explicit put causes a double put.
> >
> > Signed-off-by: Xu Wang <vulab@iscas.ac.cn>
> > ---
> >  drivers/pci/hotplug/pnv_php.c | 1 -
> >  1 file changed, 1 deletion(-)
> >
> > diff --git a/drivers/pci/hotplug/pnv_php.c b/drivers/pci/hotplug/pnv_php.c
> > index 04565162a449..ed4d1a2c3f22 100644
> > --- a/drivers/pci/hotplug/pnv_php.c
> > +++ b/drivers/pci/hotplug/pnv_php.c
> > @@ -158,7 +158,6 @@ static void pnv_php_detach_device_nodes(struct device_node *parent)
> >       for_each_child_of_node(parent, dn) {
> >               pnv_php_detach_device_nodes(dn);
> >
> > -             of_node_put(dn);
> >               of_detach_node(dn);
>
> Are you sure this is a double put? This looks to me like its meant to drive tear
> down of the device by putting a long term reference and not the short term get
> that is part of the iterator.

Yeah, the put is there is to drop the initial ref so the node can be
released. It might be worth adding a comment.

WARNING: multiple messages have this Message-ID (diff)
From: "Oliver O'Halloran" <oohall@gmail.com>
To: Tyrel Datwyler <tyreld@linux.ibm.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Paul Mackerras <paulus@samba.org>, Xu Wang <vulab@iscas.ac.cn>,
	linux-pci <linux-pci@vger.kernel.org>,
	Bjorn Helgaas <bhelgaas@google.com>,
	linuxppc-dev <linuxppc-dev@lists.ozlabs.org>
Subject: Re: [PATCH] pci/hotplug/pnv-php: Remove probable double put
Date: Wed, 8 Sep 2021 09:17:49 +1000	[thread overview]
Message-ID: <CAOSf1CGEAhXzqEU_-F39um8ri98r1Ww+AtsXJqZu4U7a_ODi9w@mail.gmail.com> (raw)
In-Reply-To: <0fa7ddfa-cd65-583e-a83f-4cbcd4e7337f@linux.ibm.com>

On Wed, Sep 8, 2021 at 8:02 AM Tyrel Datwyler <tyreld@linux.ibm.com> wrote:
>
> On 9/7/21 1:59 AM, Xu Wang wrote:
> > Device node iterators put the previous value of the index variable,
> > so an explicit put causes a double put.
> >
> > Signed-off-by: Xu Wang <vulab@iscas.ac.cn>
> > ---
> >  drivers/pci/hotplug/pnv_php.c | 1 -
> >  1 file changed, 1 deletion(-)
> >
> > diff --git a/drivers/pci/hotplug/pnv_php.c b/drivers/pci/hotplug/pnv_php.c
> > index 04565162a449..ed4d1a2c3f22 100644
> > --- a/drivers/pci/hotplug/pnv_php.c
> > +++ b/drivers/pci/hotplug/pnv_php.c
> > @@ -158,7 +158,6 @@ static void pnv_php_detach_device_nodes(struct device_node *parent)
> >       for_each_child_of_node(parent, dn) {
> >               pnv_php_detach_device_nodes(dn);
> >
> > -             of_node_put(dn);
> >               of_detach_node(dn);
>
> Are you sure this is a double put? This looks to me like its meant to drive tear
> down of the device by putting a long term reference and not the short term get
> that is part of the iterator.

Yeah, the put is there is to drop the initial ref so the node can be
released. It might be worth adding a comment.

  reply	other threads:[~2021-09-07 23:18 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-07  8:59 [PATCH] pci/hotplug/pnv-php: Remove probable double put Xu Wang
2021-09-07  8:59 ` Xu Wang
2021-09-07 11:24 ` Bjorn Helgaas
2021-09-07 11:24   ` Bjorn Helgaas
2021-09-07 22:01 ` Tyrel Datwyler
2021-09-07 22:01   ` Tyrel Datwyler
2021-09-07 23:17   ` Oliver O'Halloran [this message]
2021-09-07 23:17     ` Oliver O'Halloran

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=CAOSf1CGEAhXzqEU_-F39um8ri98r1Ww+AtsXJqZu4U7a_ODi9w@mail.gmail.com \
    --to=oohall@gmail.com \
    --cc=benh@kernel.crashing.org \
    --cc=bhelgaas@google.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-pci@vger.kernel.org \
    --cc=linuxppc-dev@lists.ozlabs.org \
    --cc=mpe@ellerman.id.au \
    --cc=paulus@samba.org \
    --cc=tyreld@linux.ibm.com \
    --cc=vulab@iscas.ac.cn \
    /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.