From 26d204afa18f7df177f21bdb3759e0098ca8f7d5 Mon Sep 17 00:00:00 2001
From: "Pallipadi, Venkatesh" <venkatesh.pallipadi@intel.com>
Date: Wed, 29 Jul 2009 13:36:10 -0700
Subject: [CPUFREQ] Fix NULL pointer dereference regression in conservative
 governor

Commit ee88415caf736b89500f16e0a545614541a45005
introduced this regression when it removed enable bit in cpu_dbs_info_s.
That added a possibility of dbs_cpufreq_notifier getting called for a
CPU that is not yet managed by conservative governor. That will happen
as the transition notifier is set as soon as one CPU switches to
conservative governor and other CPUs can get a NULL pointer dereference
without the enable bit check. Add the enable bit back again.

Reported-by: Lermytte Christophe <Christophe.Lermytte@thomson.net>
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Dave Jones <davej@redhat.com>
---
 drivers/cpufreq/cpufreq_conservative.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/cpufreq/cpufreq_conservative.c b/drivers/cpufreq/cpufreq_conservative.c
index 57490502b21..bdea7e2f94b 100644
--- a/drivers/cpufreq/cpufreq_conservative.c
+++ b/drivers/cpufreq/cpufreq_conservative.c
@@ -63,6 +63,7 @@ struct cpu_dbs_info_s {
 	unsigned int down_skip;
 	unsigned int requested_freq;
 	int cpu;
+	unsigned int enable:1;
 	/*
 	 * percpu mutex that serializes governor limit change with
 	 * do_dbs_timer invocation. We do not want do_dbs_timer to run
@@ -141,6 +142,9 @@ dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
 
 	struct cpufreq_policy *policy;
 
+	if (!this_dbs_info->enable)
+		return 0;
+
 	policy = this_dbs_info->cur_policy;
 
 	/*
@@ -497,6 +501,7 @@ static inline void dbs_timer_init(struct cpu_dbs_info_s *dbs_info)
 	int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
 	delay -= jiffies % delay;
 
+	dbs_info->enable = 1;
 	INIT_DELAYED_WORK_DEFERRABLE(&dbs_info->work, do_dbs_timer);
 	queue_delayed_work_on(dbs_info->cpu, kconservative_wq, &dbs_info->work,
 				delay);
@@ -504,6 +509,7 @@ static inline void dbs_timer_init(struct cpu_dbs_info_s *dbs_info)
 
 static inline void dbs_timer_exit(struct cpu_dbs_info_s *dbs_info)
 {
+	dbs_info->enable = 0;
 	cancel_delayed_work_sync(&dbs_info->work);
 }
 
-- 
cgit v1.2.3-70-g09d2


From 42c74b84c64633dd3badbfc2abd2ef1728b64b30 Mon Sep 17 00:00:00 2001
From: Prarit Bhargava <prarit@redhat.com>
Date: Mon, 3 Aug 2009 10:58:11 -0400
Subject: [CPUFREQ] Do not set policy for offline cpus

Suspend/Resume fails on multi socket, multi core systems because the cpufreq
code erroneously sets the per_cpu policy_cpu value when a logical cpu is
offline.

This most notably results in missing sysfs files that are used to set the
cpu frequencies of the various cpus.

Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: Dave Jones <davej@redhat.com>
---
 drivers/cpufreq/cpufreq.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index b90eda8b344..120d236c0ff 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -924,6 +924,8 @@ static int cpufreq_add_dev(struct sys_device *sys_dev)
 
 	spin_lock_irqsave(&cpufreq_driver_lock, flags);
 	for_each_cpu(j, policy->cpus) {
+		if (!cpu_online(j))
+			continue;
 		per_cpu(cpufreq_cpu_data, j) = policy;
 		per_cpu(policy_cpu, j) = policy->cpu;
 	}
-- 
cgit v1.2.3-70-g09d2


From d5194decd0a6f792b2789eebd4ddf022a248f655 Mon Sep 17 00:00:00 2001
From: Thomas Renninger <trenn@suse.de>
Date: Wed, 29 Jul 2009 11:26:20 +0200
Subject: [CPUFREQ] Fix a kobject reference bug related to managed CPUs

The first offline/online cycle is successful, the second not.
Doing:
echo 0 >cpu1/online
echo 1 >cpu1/online
echo 0 >cpu1/online

The last command will trigger:
Jul 22 14:39:50 linux kernel: [  593.210125] ------------[ cut here ]------------
Jul 22 14:39:50 linux kernel: [  593.210139] WARNING: at lib/kref.c:43 kref_get+0x23/0x2b()
Jul 22 14:39:50 linux kernel: [  593.210144] Hardware name: To Be Filled By O.E.M.
Jul 22 14:39:50 linux kernel: [  593.210148] Modules linked in: powernow_k8
Jul 22 14:39:50 linux kernel: [  593.210158] Pid: 378, comm: kondemand/2 Tainted: G        W  2.6.31-rc2 #38
Jul 22 14:39:50 linux kernel: [  593.210163] Call Trace:
Jul 22 14:39:50 linux kernel: [  593.210171]  [<ffffffff812008e8>] ? kref_get+0x23/0x2b
Jul 22 14:39:50 linux kernel: [  593.210181]  [<ffffffff81041926>] warn_slowpath_common+0x77/0xa4
Jul 22 14:39:50 linux kernel: [  593.210190]  [<ffffffff81041962>] warn_slowpath_null+0xf/0x11
Jul 22 14:39:50 linux kernel: [  593.210198]  [<ffffffff812008e8>] kref_get+0x23/0x2b
Jul 22 14:39:50 linux kernel: [  593.210206]  [<ffffffff811ffa19>] kobject_get+0x1a/0x22
Jul 22 14:39:50 linux kernel: [  593.210214]  [<ffffffff813e815d>] cpufreq_cpu_get+0x8a/0xcb
Jul 22 14:39:50 linux kernel: [  593.210222]  [<ffffffff813e87d1>] __cpufreq_driver_getavg+0x1d/0x67
Jul 22 14:39:50 linux kernel: [  593.210231]  [<ffffffff813ea18f>] do_dbs_timer+0x158/0x27f
Jul 22 14:39:50 linux kernel: [  593.210240]  [<ffffffff810529ea>] worker_thread+0x200/0x313
...

The output continues on every do_dbs_timer ondemand freq checking poll.
This regression was introduced by git commit:
3f4a782b5ce2698b1870b5a7b573cd721d4fce33

The policy is released when the cpufreq device is removed in:
__cpufreq_remove_dev():
	/* if this isn't the CPU which is the parent of the kobj, we
	 * only need to unlink, put and exit
	 */

Not creating the symlink is not sever at all.
As long as:
sysfs_remove_link(&sys_dev->kobj, "cpufreq");
handles it gracefully that the symlink did not exist.
Possibly no error should be returned at all, because ondemand
governor would still provide the same functionality.
Userspace in userspace gov case might be confused if the link
is missing.

Resolves http://bugzilla.kernel.org/show_bug.cgi?id=13903

CC: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
CC: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Thomas Renninger <trenn@suse.de>
Signed-off-by: Dave Jones <davej@redhat.com>
---
 drivers/cpufreq/cpufreq.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 120d236c0ff..bd74a0b1217 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -858,6 +858,8 @@ static int cpufreq_add_dev(struct sys_device *sys_dev)
 
 		/* Check for existing affected CPUs.
 		 * They may not be aware of it due to CPU Hotplug.
+		 * cpufreq_cpu_put is called when the device is removed
+		 * in __cpufreq_remove_dev()
 		 */
 		managed_policy = cpufreq_cpu_get(j);
 		if (unlikely(managed_policy)) {
@@ -884,7 +886,7 @@ static int cpufreq_add_dev(struct sys_device *sys_dev)
 			ret = sysfs_create_link(&sys_dev->kobj,
 						&managed_policy->kobj,
 						"cpufreq");
-			if (!ret)
+			if (ret)
 				cpufreq_cpu_put(managed_policy);
 			/*
 			 * Success. We only needed to be added to the mask.
-- 
cgit v1.2.3-70-g09d2


From 4bc5d34135039566b8d6efa2de7515b2be505da8 Mon Sep 17 00:00:00 2001
From: Dave Jones <davej@redhat.com>
Date: Tue, 4 Aug 2009 14:03:25 -0400
Subject: [CPUFREQ] Make cpufreq suspend code conditional on powerpc.

The suspend code runs with interrupts disabled, and the powerpc workaround we
do in the cpufreq suspend hook calls the drivers ->get method.

powernow-k8's ->get does an smp_call_function_single
which needs interrupts enabled

cpufreq's suspend/resume code was added in 42d4dc3f4e1e to work around
a hardware problem on ppc powerbooks.  If we make all this code
conditional on powerpc, we avoid the issue above.

Signed-off-by: Dave Jones <davej@redhat.com>
---
 drivers/cpufreq/cpufreq.c | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index bd74a0b1217..fd69086d08d 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1248,13 +1248,22 @@ EXPORT_SYMBOL(cpufreq_get);
 
 static int cpufreq_suspend(struct sys_device *sysdev, pm_message_t pmsg)
 {
-	int cpu = sysdev->id;
 	int ret = 0;
+
+#ifdef __powerpc__
+	int cpu = sysdev->id;
 	unsigned int cur_freq = 0;
 	struct cpufreq_policy *cpu_policy;
 
 	dprintk("suspending cpu %u\n", cpu);
 
+	/*
+	 * This whole bogosity is here because Powerbooks are made of fail.
+	 * No sane platform should need any of the code below to be run.
+	 * (it's entirely the wrong thing to do, as driver->get may
+	 *  reenable interrupts on some architectures).
+	 */
+
 	if (!cpu_online(cpu))
 		return 0;
 
@@ -1313,6 +1322,7 @@ static int cpufreq_suspend(struct sys_device *sysdev, pm_message_t pmsg)
 
 out:
 	cpufreq_cpu_put(cpu_policy);
+#endif	/* __powerpc__ */
 	return ret;
 }
 
@@ -1326,12 +1336,18 @@ out:
  */
 static int cpufreq_resume(struct sys_device *sysdev)
 {
-	int cpu = sysdev->id;
 	int ret = 0;
+
+#ifdef __powerpc__
+	int cpu = sysdev->id;
 	struct cpufreq_policy *cpu_policy;
 
 	dprintk("resuming cpu %u\n", cpu);
 
+	/* As with the ->suspend method, all the code below is
+	 * only necessary because Powerbooks suck.
+	 * See commit 42d4dc3f4e1e for jokes. */
+
 	if (!cpu_online(cpu))
 		return 0;
 
@@ -1395,6 +1411,7 @@ out:
 	schedule_work(&cpu_policy->update);
 fail:
 	cpufreq_cpu_put(cpu_policy);
+#endif	/* __powerpc__ */
 	return ret;
 }
 
-- 
cgit v1.2.3-70-g09d2