Re: v3.13.5 intel_pstate: cpufreq: __cpufreq_add_dev: ->get() failed

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On Tuesday, March 11, 2014 01:55:23 PM Dirk Brandewie wrote:
> On 03/11/2014 01:57 PM, Rafael J. Wysocki wrote:
> > On Tuesday, March 11, 2014 09:52:42 PM Rafael J. Wysocki wrote:
> >> On Tuesday, March 11, 2014 01:17:20 PM Dirk Brandewie wrote:
> >>> On 03/11/2014 01:20 PM, Rafael J. Wysocki wrote:
> >>>> On Tuesday, March 11, 2014 10:58:59 AM Dirk Brandewie wrote:
> >>>>> Hi Patrick,
> >>>>>
> >>>>> Sorry for the slow response you caught me taking a few days off :-)
> >>>>>
> >>>>> On 03/07/2014 07:49 AM, Patrik Lundquist wrote:
> >>>>>> Hi,
> >>>>>>
> >>>>>> booting 3.13.5 on a dual socket Ivy Bridge-EP resulted in this error:
> >>>>>>
> >>>>>> [    0.194139] smpboot: CPU0: Intel(R) Xeon(R) CPU E5-2687W v2 @
> >>>>>> 3.40GHz (fam: 06, model: 3e, stepping: 04)
> >>>>>> ...
> >>>>>> [    0.246755] x86: Booting SMP configuration:
> >>>>>> [    0.250935] .... node  #0, CPUs:        #1  #2  #3  #4  #5  #6  #7
> >>>>>> [    0.357648] .... node  #1, CPUs:    #8  #9 #10 #11 #12 #13 #14 #15
> >>>>>> [    0.553293] x86: Booted up 2 nodes, 16 CPUs
> >>>>>> [    0.557666] smpboot: Total of 16 processors activated (108850.19 BogoMIPS)
> >>>>>> ...
> >>>>>> [    5.210204] Intel P-state driver initializing.
> >>>>>> [    5.232407] Intel pstate controlling: cpu 0
> >>>>>> [    5.253628] Intel pstate controlling: cpu 1
> >>>>>> [    5.274899] cpufreq: __cpufreq_add_dev: ->get() failed
> >>>>>> [    5.294856] Intel pstate controlling: cpu 2
> >>>>>> [    5.313553] Intel pstate controlling: cpu 3
> >>>>>> [    5.332526] Intel pstate controlling: cpu 4
> >>>>>> [    5.352347] Intel pstate controlling: cpu 5
> >>>>>> [    5.372112] Intel pstate controlling: cpu 6
> >>>>>> [    5.391097] Intel pstate controlling: cpu 7
> >>>>>> [    5.410272] Intel pstate controlling: cpu 8
> >>>>>> [    5.429092] Intel pstate controlling: cpu 9
> >>>>>> [    5.447714] Intel pstate controlling: cpu 10
> >>>>>> [    5.465872] Intel pstate controlling: cpu 11
> >>>>>> [    5.482942] Intel pstate controlling: cpu 12
> >>>>>> [    5.498414] Intel pstate controlling: cpu 13
> >>>>>> [    5.513586] Intel pstate controlling: cpu 14
> >>>>>> [    5.529200] Intel pstate controlling: cpu 15
> >>>>>>
> >>>>>> CPU 1 is alive and well but missing the cpufreq driver. The system is
> >>>>>> running fine otherwise.
> >>>>>
> >>>>> This is a regression introduced by commit
> >>>>> da60ce9f2fa cpufreq: call cpufreq_driver->get() after calling ->init()
> >>>>
> >>>> So the problem is that ->get() may return 0 in intel_pstate and that causes
> >>>> the core's _add function to abort?  That would mean sample->freq equal to 0,
> >>>> which shouldn't happen after intel_pstate_sample() called by intel_pstate_init_cpu().
> >>>>
> >>>> Or am I missing anything?
> >>>>
> >>>
> >>> The problem is that the core has been running less than 1% of the time based on
> >>> the absolute values of aperf/mperf and the second sample has not been taken to
> >>> get a more precise delta.
> >>>
> >>> I thought about running sample twice during init but didn't want to propose it
> >>> until I made sure I was not going to break anything else.
> >>
> >> Well, ->setpolicy drivers are a special case anyway, so we can simply skip the
> >> current frequency updates in __cpufreq_add_dev() and cpufreq_update_policy()
> >> for them.
> >
> > In other words, we can do something like in the patch below I suppose?
> >
> > Rafael
> >
> >
> > ---
> >   drivers/cpufreq/cpufreq.c |    4 ++--
> >   1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > Index: linux-pm/drivers/cpufreq/cpufreq.c
> > ===================================================================
> > --- linux-pm.orig/drivers/cpufreq/cpufreq.c
> > +++ linux-pm/drivers/cpufreq/cpufreq.c
> > @@ -1137,7 +1137,7 @@ static int __cpufreq_add_dev(struct devi
> >   		per_cpu(cpufreq_cpu_data, j) = policy;
> >   	write_unlock_irqrestore(&cpufreq_driver_lock, flags);
> >
> > -	if (cpufreq_driver->get) {
> > +	if (cpufreq_driver->get && !cpufreq_driver->setpolicy) {
> >   		policy->cur = cpufreq_driver->get(policy->cpu);
> >   		if (!policy->cur) {
> >   			pr_err("%s: ->get() failed\n", __func__);
> > @@ -2150,7 +2150,7 @@ int cpufreq_update_policy(unsigned int c
> >   	 * BIOS might change freq behind our back
> >   	 * -> ask driver for current freq and notify governors about a change
> >   	 */
> > -	if (cpufreq_driver->get) {
> > +	if (cpufreq_driver->get && !cpufreq_driver->setpolicy) {
> >   		new_policy.cur = cpufreq_driver->get(cpu);
> >   		if (WARN_ON(!new_policy.cur)) {
> >   			ret = -EIO;
> >
> or use has_target()

Yes.

Modified patch is appended.  Patrik, can you please check if it helps?

---
 drivers/cpufreq/cpufreq.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Index: linux-pm/drivers/cpufreq/cpufreq.c
===================================================================
--- linux-pm.orig/drivers/cpufreq/cpufreq.c
+++ linux-pm/drivers/cpufreq/cpufreq.c
@@ -1137,7 +1137,7 @@ static int __cpufreq_add_dev(struct devi
 		per_cpu(cpufreq_cpu_data, j) = policy;
 	write_unlock_irqrestore(&cpufreq_driver_lock, flags);
 
-	if (cpufreq_driver->get) {
+	if (cpufreq_driver->get && has_target()) {
 		policy->cur = cpufreq_driver->get(policy->cpu);
 		if (!policy->cur) {
 			pr_err("%s: ->get() failed\n", __func__);
@@ -2150,7 +2150,7 @@ int cpufreq_update_policy(unsigned int c
 	 * BIOS might change freq behind our back
 	 * -> ask driver for current freq and notify governors about a change
 	 */
-	if (cpufreq_driver->get) {
+	if (cpufreq_driver->get && has_target()) {
 		new_policy.cur = cpufreq_driver->get(cpu);
 		if (WARN_ON(!new_policy.cur)) {
 			ret = -EIO;

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