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[tip:smp/hotplug] cpufreq: Convert to hotplug state machine

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  [tip:smp/hotplug] cpufreq: Convert to hotplug state machine tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2016-09-19 22:00 +0200
    [PATCH] cpufreq: fix up conversion to hotplug state machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-09-20 17:00 +0200
      [tip:smp/hotplug] cpufreq: Fix up conversion to hotplug state  machine tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2016-09-20 17:10 +0200
        Re: [tip:smp/hotplug] cpufreq: Fix up conversion to hotplug state  machine Borislav Petkov <bp@alien8.de> - 2016-09-20 18:10 +0200
      Re: [PATCH] cpufreq: fix up conversion to hotplug state machine "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-09-20 18:20 +0200

#1486823 — [tip:smp/hotplug] cpufreq: Convert to hotplug state machine

Commit-ID:  27622b061eb4bb4d16b5d61219ac10a792010321
Gitweb:     http://git.kernel.org/tip/27622b061eb4bb4d16b5d61219ac10a792010321
Author:     Sebastian Andrzej Siewior <bigeasy@linutronix.de>
AuthorDate: Tue, 6 Sep 2016 19:04:48 +0200
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Mon, 19 Sep 2016 21:44:29 +0200

cpufreq: Convert to hotplug state machine

Install the callbacks via the state machine.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: linux-pm@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Viresh Kumar <viresh.kumar@linaro.or
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160906170457.32393-13-bigeasy@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

---
 drivers/cpufreq/cpufreq.c | 38 ++++++++++++--------------------------
 1 file changed, 12 insertions(+), 26 deletions(-)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 3dd4884..e0bc632 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1358,7 +1358,7 @@ static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif)
 	return add_cpu_dev_symlink(policy, cpu);
 }
 
-static void cpufreq_offline(unsigned int cpu)
+static int cpufreq_offline(unsigned int cpu)
 {
 	struct cpufreq_policy *policy;
 	int ret;
@@ -1368,7 +1368,7 @@ static void cpufreq_offline(unsigned int cpu)
 	policy = cpufreq_cpu_get_raw(cpu);
 	if (!policy) {
 		pr_debug("%s: No cpu_data found\n", __func__);
-		return;
+		return 0;
 	}
 
 	down_write(&policy->rwsem);
@@ -1417,6 +1417,7 @@ static void cpufreq_offline(unsigned int cpu)
 
 unlock:
 	up_write(&policy->rwsem);
+	return 0;
 }
 
 /**
@@ -2332,28 +2333,6 @@ unlock:
 }
 EXPORT_SYMBOL(cpufreq_update_policy);
 
-static int cpufreq_cpu_callback(struct notifier_block *nfb,
-					unsigned long action, void *hcpu)
-{
-	unsigned int cpu = (unsigned long)hcpu;
-
-	switch (action & ~CPU_TASKS_FROZEN) {
-	case CPU_ONLINE:
-	case CPU_DOWN_FAILED:
-		cpufreq_online(cpu);
-		break;
-
-	case CPU_DOWN_PREPARE:
-		cpufreq_offline(cpu);
-		break;
-	}
-	return NOTIFY_OK;
-}
-
-static struct notifier_block __refdata cpufreq_cpu_notifier = {
-	.notifier_call = cpufreq_cpu_callback,
-};
-
 /*********************************************************************
  *               BOOST						     *
  *********************************************************************/
@@ -2455,6 +2434,7 @@ EXPORT_SYMBOL_GPL(cpufreq_boost_enabled);
 /*********************************************************************
  *               REGISTER / UNREGISTER CPUFREQ DRIVER                *
  *********************************************************************/
+static enum cpuhp_state hp_online;
 
 /**
  * cpufreq_register_driver - register a CPU Frequency driver
@@ -2517,7 +2497,13 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data)
 		goto err_if_unreg;
 	}
 
-	register_hotcpu_notifier(&cpufreq_cpu_notifier);
+	ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "cpufreq:online",
+					cpufreq_online,
+					cpufreq_offline);
+	if (ret < 0)
+		goto err_if_unreg;
+	hp_online = ret;
+
 	pr_debug("driver %s up and running\n", driver_data->name);
 	goto out;
 
@@ -2556,7 +2542,7 @@ int cpufreq_unregister_driver(struct cpufreq_driver *driver)
 	get_online_cpus();
 	subsys_interface_unregister(&cpufreq_interface);
 	remove_boost_sysfs_file();
-	unregister_hotcpu_notifier(&cpufreq_cpu_notifier);
+	cpuhp_remove_state_nocalls(hp_online);
 
 	write_lock_irqsave(&cpufreq_driver_lock, flags);
 

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#1487407 — [PATCH] cpufreq: fix up conversion to hotplug state machine

The function cpufreq_register_driver() returns zero on success and since
commit 27622b061eb4 ("cpufreq: Convert to hotplug state machine")
erroneously a positive number. Due to the "if (x) assume_error" construct
all callers assumed an error and things went south.
This patch resets the return value back to zero in the success case.

Fixes: 27622b061eb4 ("cpufreq: Convert to hotplug state machine")
Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 drivers/cpufreq/cpufreq.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index e0bc632a259e..8b44de4d7438 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -2503,6 +2503,7 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data)
 	if (ret < 0)
 		goto err_if_unreg;
 	hp_online = ret;
+	ret = 0;
 
 	pr_debug("driver %s up and running\n", driver_data->name);
 	goto out;
-- 
2.9.3

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#1487418 — [tip:smp/hotplug] cpufreq: Fix up conversion to hotplug state machine

Commit-ID:  5372e054a1928fe704cf0a5e2e139645a777b50a
Gitweb:     http://git.kernel.org/tip/5372e054a1928fe704cf0a5e2e139645a777b50a
Author:     Sebastian Andrzej Siewior <bigeasy@linutronix.de>
AuthorDate: Tue, 20 Sep 2016 16:56:28 +0200
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Tue, 20 Sep 2016 16:59:21 +0200

cpufreq: Fix up conversion to hotplug state machine

The function cpufreq_register_driver() returns zero on success and since
commit 27622b061eb4 ("cpufreq: Convert to hotplug state machine")
erroneously a positive number. Due to the "if (x) assume_error" construct
all callers assumed an error and as a consequence the cpu freq kworker
crashes with a NULL pointer dereference.

Reset the return value back to zero in the success case.

Fixes: 27622b061eb4 ("cpufreq: Convert to hotplug state machine")
Reported-by: Borislav Petkov <bp@alien8.de>
Reported-and-tested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: peterz@infradead.org
Cc: rjw@rjwysocki.net
Link: http://lkml.kernel.org/r/20160920145628.lp2bmq72ip3oiash@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

---
 drivers/cpufreq/cpufreq.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index e0bc632..8b44de4 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -2503,6 +2503,7 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data)
 	if (ret < 0)
 		goto err_if_unreg;
 	hp_online = ret;
+	ret = 0;
 
 	pr_debug("driver %s up and running\n", driver_data->name);
 	goto out;

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#1487481 — Re: [tip:smp/hotplug] cpufreq: Fix up conversion to hotplug state machine

On Tue, Sep 20, 2016 at 08:07:08AM -0700, tip-bot for Sebastian Andrzej Siewior wrote:
> Commit-ID:  5372e054a1928fe704cf0a5e2e139645a777b50a
> Gitweb:     http://git.kernel.org/tip/5372e054a1928fe704cf0a5e2e139645a777b50a
> Author:     Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> AuthorDate: Tue, 20 Sep 2016 16:56:28 +0200
> Committer:  Thomas Gleixner <tglx@linutronix.de>
> CommitDate: Tue, 20 Sep 2016 16:59:21 +0200
> 
> cpufreq: Fix up conversion to hotplug state machine
> 
> The function cpufreq_register_driver() returns zero on success and since
> commit 27622b061eb4 ("cpufreq: Convert to hotplug state machine")
> erroneously a positive number. Due to the "if (x) assume_error" construct
> all callers assumed an error and as a consequence the cpu freq kworker
> crashes with a NULL pointer dereference.
> 
> Reset the return value back to zero in the success case.
> 
> Fixes: 27622b061eb4 ("cpufreq: Convert to hotplug state machine")
> Reported-by: Borislav Petkov <bp@alien8.de>

	-and-tested-by: me.

Thanks!

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.

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#1487503 — Re: [PATCH] cpufreq: fix up conversion to hotplug state machine

On Tuesday, September 20, 2016 04:56:28 PM Sebastian Andrzej Siewior wrote:
> The function cpufreq_register_driver() returns zero on success and since
> commit 27622b061eb4 ("cpufreq: Convert to hotplug state machine")
> erroneously a positive number. Due to the "if (x) assume_error" construct
> all callers assumed an error and things went south.
> This patch resets the return value back to zero in the success case.
> 
> Fixes: 27622b061eb4 ("cpufreq: Convert to hotplug state machine")
> Reported-by: Borislav Petkov <bp@alien8.de>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

ACK

> ---
>  drivers/cpufreq/cpufreq.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index e0bc632a259e..8b44de4d7438 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -2503,6 +2503,7 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data)
>  	if (ret < 0)
>  		goto err_if_unreg;
>  	hp_online = ret;
> +	ret = 0;
>  
>  	pr_debug("driver %s up and running\n", driver_data->name);
>  	goto out;
> 

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