linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Ido Schimmel <idosch@idosch.org>
Cc: x86 <x86@kernel.org>, LKML <linux-kernel@vger.kernel.org>,
	Len Brown <len.brown@intel.com>,
	Linux PM <linux-pm@vger.kernel.org>,
	Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
	Laura Abbott <labbott@fedoraproject.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@kernel.org>,
	Simon Schricker <sschricker@suse.de>,
	Borislav Petkov <bp@suse.de>, Hannes Reinecke <hare@suse.de>
Subject: Re: [PATCH 2/2] PM / arch: x86: MSR_IA32_ENERGY_PERF_BIAS sysfs interface
Date: Thu, 09 May 2019 19:18:28 +0200	[thread overview]
Message-ID: <1627338.1fd8ofggM8@kreacher> (raw)
In-Reply-To: <20190509102315.GA31824@splinter>

On Thursday, May 9, 2019 12:23:15 PM CEST Ido Schimmel wrote:
> On Thu, Mar 21, 2019 at 11:20:17PM +0100, Rafael J. Wysocki wrote:
> > +static struct attribute *intel_epb_attrs[] = {
> > +	&dev_attr_energy_perf_bias.attr,
> > +	NULL
> > +};
> > +
> > +static const struct attribute_group intel_epb_attr_group = {
> > +	.name = power_group_name,
> > +	.attrs =  intel_epb_attrs
> > +};
> > +
> >  static int intel_epb_online(unsigned int cpu)
> >  {
> > +	struct device *cpu_dev = get_cpu_device(cpu);
> > +
> >  	intel_epb_restore();
> > +	if (!cpuhp_tasks_frozen)
> > +		sysfs_merge_group(&cpu_dev->kobj, &intel_epb_attr_group);
> > +
> >  	return 0;
> >  }
> >  
> >  static int intel_epb_offline(unsigned int cpu)
> >  {
> > -	return intel_epb_save();
> > +	struct device *cpu_dev = get_cpu_device(cpu);
> > +
> > +	if (!cpuhp_tasks_frozen)
> > +		sysfs_unmerge_group(&cpu_dev->kobj, &intel_epb_attr_group);
> > +
> > +	intel_epb_save();
> > +	return 0;
> >  }
> 
> Hi,
> 
> I just booted net-next and got the following NULL pointer dereference
> [1] during boot. I believe it is caused by this patch.

I think you're right, sorry about this.

> CONFIG_PM is disabled in my config which means 'power_group_name' is
> defined as NULL. When I enable CONFIG_PM the issue is not reproduced.

So does the patch below fix it for you?

---
 arch/x86/kernel/cpu/intel_epb.c |   22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

Index: linux-pm/arch/x86/kernel/cpu/intel_epb.c
===================================================================
--- linux-pm.orig/arch/x86/kernel/cpu/intel_epb.c
+++ linux-pm/arch/x86/kernel/cpu/intel_epb.c
@@ -97,6 +97,7 @@ static void intel_epb_restore(void)
 	wrmsrl(MSR_IA32_ENERGY_PERF_BIAS, (epb & ~EPB_MASK) | val);
 }
 
+#ifdef CONFIG_PM
 static struct syscore_ops intel_epb_syscore_ops = {
 	.suspend = intel_epb_save,
 	.resume = intel_epb_restore,
@@ -193,6 +194,25 @@ static int intel_epb_offline(unsigned in
 	return 0;
 }
 
+static inline void register_intel_ebp_syscore_ops(void)
+{
+	register_syscore_ops(&intel_epb_syscore_ops);
+}
+#else /* !CONFIG_PM */
+static int intel_epb_online(unsigned int cpu)
+{
+	intel_epb_restore();
+	return 0;
+}
+
+static int intel_epb_offline(unsigned int cpu)
+{
+	return intel_epb_save();
+}
+
+static inline void register_intel_ebp_syscore_ops(void) {}
+#endif
+
 static __init int intel_epb_init(void)
 {
 	int ret;
@@ -206,7 +226,7 @@ static __init int intel_epb_init(void)
 	if (ret < 0)
 		goto err_out_online;
 
-	register_syscore_ops(&intel_epb_syscore_ops);
+	register_intel_ebp_syscore_ops();
 	return 0;
 
 err_out_online:




  reply	other threads:[~2019-05-09 17:18 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-21 22:12 [PATCH 0/2] PM / arch: x86: MSR_IA32_ENERGY_PERF_BIAS handling fixes and sysfs i/f Rafael J. Wysocki
2019-03-21 22:18 ` [PATCH 1/2] PM / arch: x86: Rework the MSR_IA32_ENERGY_PERF_BIAS handling Rafael J. Wysocki
2019-03-22  9:03   ` Hannes Reinecke
2019-03-22 14:28   ` Borislav Petkov
2019-03-22 14:31     ` Thomas Gleixner
2019-03-22 14:35       ` Borislav Petkov
2019-03-22 16:12         ` Thomas Gleixner
2019-03-22 16:52           ` Joe Perches
2019-03-25 10:06     ` Rafael J. Wysocki
2019-03-22 16:27   ` Thomas Renninger
2019-03-22 16:43     ` Borislav Petkov
2019-03-25 11:31   ` Borislav Petkov
2019-03-21 22:20 ` [PATCH 2/2] PM / arch: x86: MSR_IA32_ENERGY_PERF_BIAS sysfs interface Rafael J. Wysocki
2019-03-22  9:03   ` Hannes Reinecke
2019-03-22 14:46   ` Borislav Petkov
2019-03-25 10:01     ` Rafael J. Wysocki
2019-03-22 15:00   ` Peter Zijlstra
2019-03-25  9:56     ` Rafael J. Wysocki
2019-03-25 11:32   ` Borislav Petkov
2019-05-09 10:23   ` Ido Schimmel
2019-05-09 17:18     ` Rafael J. Wysocki [this message]
2019-05-09 17:43       ` Ido Schimmel
2019-05-09 21:28         ` [PATCH] x86: intel_epb: Take CONFIG_PM into account Rafael J. Wysocki
2019-05-10  6:01           ` Ingo Molnar
2019-05-27 10:56         ` [PATCH] x86: intel_epb: Do not build when CONFIG_PM is unset Rafael J. Wysocki
2019-05-30  7:47           ` Ingo Molnar

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=1627338.1fd8ofggM8@kreacher \
    --to=rjw@rjwysocki.net \
    --cc=bp@suse.de \
    --cc=hare@suse.de \
    --cc=idosch@idosch.org \
    --cc=labbott@fedoraproject.org \
    --cc=len.brown@intel.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-pm@vger.kernel.org \
    --cc=mingo@kernel.org \
    --cc=peterz@infradead.org \
    --cc=srinivas.pandruvada@linux.intel.com \
    --cc=sschricker@suse.de \
    --cc=tglx@linutronix.de \
    --cc=x86@kernel.org \
    --subject='Re: [PATCH 2/2] PM / arch: x86: MSR_IA32_ENERGY_PERF_BIAS sysfs interface' \
    /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

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).