All of lore.kernel.org
 help / color / mirror / Atom feed
From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: Tony Lindgren <tony@atomide.com>
Cc: Liang He <windhl@126.com>,
	andre.przywara@arm.com, thierry.reding@gmail.com,
	jonathanh@nvidia.com, linux-arm-kernel@lists.infradead.org,
	linux-omap@vger.kernel.org, linux-tegra@vger.kernel.org,
	Krzysztof Kozlowski <krzk@kernel.org>
Subject: Re: [PATCH] arm/mach: Hold reference returned by of_find_xxx APIs
Date: Tue, 28 Jun 2022 17:16:04 +0100	[thread overview]
Message-ID: <YrspRE+g7QvzOvgr@shell.armlinux.org.uk> (raw)
In-Reply-To: <Yrp8sUMdmfYsiUsD@atomide.com>

On Tue, Jun 28, 2022 at 06:59:45AM +0300, Tony Lindgren wrote:
> * Liang He <windhl@126.com> [220621 12:14]:
> > diff --git a/arch/arm/mach-omap2/pmic-cpcap.c b/arch/arm/mach-omap2/pmic-cpcap.c
> > index 668dc84fd31e..a7368d657aa8 100644
> > --- a/arch/arm/mach-omap2/pmic-cpcap.c
> > +++ b/arch/arm/mach-omap2/pmic-cpcap.c
> > @@ -238,8 +238,11 @@ static struct omap_voltdm_pmic omap4_fan_iva = {
> >  int __init omap4_cpcap_init(void)
> >  {
> >  	struct voltagedomain *voltdm;
> > +	struct device_node *np;
> >  
> > -	if (!of_find_compatible_node(NULL, NULL, "motorola,cpcap"))
> > +	np = of_find_compatible_node(NULL, NULL, "motorola,cpcap");
> > +	of_node_put(np);
> > +	if (!np)
> >  		return -ENODEV;
> 
> Hmm so here you are checking for !np after of_node_put()?

This is permissible, because the value of the _pointer_ is being
checked without dereferencing the pointer. So the fact that the
node may have been freed is actually immaterial.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!

WARNING: multiple messages have this Message-ID (diff)
From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: Tony Lindgren <tony@atomide.com>
Cc: Liang He <windhl@126.com>,
	andre.przywara@arm.com, thierry.reding@gmail.com,
	jonathanh@nvidia.com, linux-arm-kernel@lists.infradead.org,
	linux-omap@vger.kernel.org, linux-tegra@vger.kernel.org,
	Krzysztof Kozlowski <krzk@kernel.org>
Subject: Re: [PATCH] arm/mach: Hold reference returned by of_find_xxx APIs
Date: Tue, 28 Jun 2022 17:16:04 +0100	[thread overview]
Message-ID: <YrspRE+g7QvzOvgr@shell.armlinux.org.uk> (raw)
In-Reply-To: <Yrp8sUMdmfYsiUsD@atomide.com>

On Tue, Jun 28, 2022 at 06:59:45AM +0300, Tony Lindgren wrote:
> * Liang He <windhl@126.com> [220621 12:14]:
> > diff --git a/arch/arm/mach-omap2/pmic-cpcap.c b/arch/arm/mach-omap2/pmic-cpcap.c
> > index 668dc84fd31e..a7368d657aa8 100644
> > --- a/arch/arm/mach-omap2/pmic-cpcap.c
> > +++ b/arch/arm/mach-omap2/pmic-cpcap.c
> > @@ -238,8 +238,11 @@ static struct omap_voltdm_pmic omap4_fan_iva = {
> >  int __init omap4_cpcap_init(void)
> >  {
> >  	struct voltagedomain *voltdm;
> > +	struct device_node *np;
> >  
> > -	if (!of_find_compatible_node(NULL, NULL, "motorola,cpcap"))
> > +	np = of_find_compatible_node(NULL, NULL, "motorola,cpcap");
> > +	of_node_put(np);
> > +	if (!np)
> >  		return -ENODEV;
> 
> Hmm so here you are checking for !np after of_node_put()?

This is permissible, because the value of the _pointer_ is being
checked without dereferencing the pointer. So the fact that the
node may have been freed is actually immaterial.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2022-06-28 16:25 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-21  9:19 [PATCH] arm/mach: Hold reference returned by of_find_xxx APIs Liang He
2022-06-21  9:19 ` Liang He
2022-06-22  8:51 ` Krzysztof Kozlowski
2022-06-22  8:51   ` Krzysztof Kozlowski
2022-06-28  3:59 ` Tony Lindgren
2022-06-28  3:59   ` Tony Lindgren
2022-06-28  4:05   ` Liang He
2022-06-28  4:05     ` Liang He
2022-06-28 16:16   ` Russell King (Oracle) [this message]
2022-06-28 16:16     ` Russell King (Oracle)
2022-06-29  8:37     ` Tony Lindgren
2022-06-29  8:37       ` Tony Lindgren

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=YrspRE+g7QvzOvgr@shell.armlinux.org.uk \
    --to=linux@armlinux.org.uk \
    --cc=andre.przywara@arm.com \
    --cc=jonathanh@nvidia.com \
    --cc=krzk@kernel.org \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-omap@vger.kernel.org \
    --cc=linux-tegra@vger.kernel.org \
    --cc=thierry.reding@gmail.com \
    --cc=tony@atomide.com \
    --cc=windhl@126.com \
    /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.