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Commit 8fa938ac authored by Nishanth Menon's avatar Nishanth Menon Committed by Rafael J. Wysocki
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PM / devfreq: exynos4_bus: honor RCU lock usage 



OPP pointers cannot be expected to be valid beyond the boundary
of rcu_read_lock and rcu_read_unlock. Unfortunately, the current
exynos4 busfreq driver does not honor the usage constraint and stores
the OPP pointer in struct busfreq_data. This could potentially
become invalid later such as: across devfreq opp change decisions,
resulting in unpredictable behavior.

To fix this, we introduce a busfreq specific busfreq_opp_info
structure which is used to handle OPP information. OPP information
is de-referenced to voltage and frequency pairs as needed into
busfreq_opp_info structure and used as needed.

Signed-off-by: default avatarNishanth Menon <nm@ti.com>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent bcb27549

drivers/devfreq/exynos4_bus.c

+67 −27
Original line number Diff line number Diff line
@@ -73,6 +73,16 @@ enum busclk_level_idx { 
#define EX4210_LV_NUM	(LV_2 + 1)

#define EX4x12_LV_NUM	(LV_4 + 1)



/**

 * struct busfreq_opp_info - opp information for bus

 * @rate:	Frequency in hertz

 * @volt:	Voltage in microvolts corresponding to this OPP

 */

struct busfreq_opp_info {

	unsigned long rate;

	unsigned long volt;

};



struct busfreq_data {

	enum exynos4_busf_type type;

	struct device *dev;
@@ -80,7 +90,7 @@ struct busfreq_data { 
	bool disabled;

	struct regulator *vdd_int;

	struct regulator *vdd_mif; /* Exynos4412/4212 only */

	struct opp *curr_opp;

	struct busfreq_opp_info curr_oppinfo;

	struct exynos4_ppmu dmc[2];



	struct notifier_block pm_notifier;
@@ -296,13 +306,14 @@ static unsigned int exynos4x12_clkdiv_sclkip[][3] = { 
};





static int exynos4210_set_busclk(struct busfreq_data *data, struct opp *opp)

static int exynos4210_set_busclk(struct busfreq_data *data,

				 struct busfreq_opp_info *oppi)

{

	unsigned int index;

	unsigned int tmp;



	for (index = LV_0; index < EX4210_LV_NUM; index++)

		if (opp_get_freq(opp) == exynos4210_busclk_table[index].clk)

		if (oppi->rate == exynos4210_busclk_table[index].clk)

			break;



	if (index == EX4210_LV_NUM)
@@ -361,13 +372,14 @@ static int exynos4210_set_busclk(struct busfreq_data *data, struct opp *opp) 
	return 0;

}



static int exynos4x12_set_busclk(struct busfreq_data *data, struct opp *opp)

static int exynos4x12_set_busclk(struct busfreq_data *data,

				 struct busfreq_opp_info *oppi)

{

	unsigned int index;

	unsigned int tmp;



	for (index = LV_0; index < EX4x12_LV_NUM; index++)

		if (opp_get_freq(opp) == exynos4x12_mifclk_table[index].clk)

		if (oppi->rate == exynos4x12_mifclk_table[index].clk)

			break;



	if (index == EX4x12_LV_NUM)
@@ -576,11 +588,12 @@ static int exynos4x12_get_intspec(unsigned long mifclk) 
	return -EINVAL;

}



static int exynos4_bus_setvolt(struct busfreq_data *data, struct opp *opp,

			       struct opp *oldopp)

static int exynos4_bus_setvolt(struct busfreq_data *data,

			       struct busfreq_opp_info *oppi,

			       struct busfreq_opp_info *oldoppi)

{

	int err = 0, tmp;

	unsigned long volt = opp_get_voltage(opp);

	unsigned long volt = oppi->volt;



	switch (data->type) {

	case TYPE_BUSF_EXYNOS4210:
@@ -595,11 +608,11 @@ static int exynos4_bus_setvolt(struct busfreq_data *data, struct opp *opp, 
		if (err)

			break;



		tmp = exynos4x12_get_intspec(opp_get_freq(opp));

		tmp = exynos4x12_get_intspec(oppi->rate);

		if (tmp < 0) {

			err = tmp;

			regulator_set_voltage(data->vdd_mif,

					      opp_get_voltage(oldopp),

					      oldoppi->volt,

					      MAX_SAFEVOLT);

			break;

		}
@@ -609,7 +622,7 @@ static int exynos4_bus_setvolt(struct busfreq_data *data, struct opp *opp, 
		/*  Try to recover */

		if (err)

			regulator_set_voltage(data->vdd_mif,

					      opp_get_voltage(oldopp),

					      oldoppi->volt,

					      MAX_SAFEVOLT);

		break;

	default:
@@ -626,17 +639,26 @@ static int exynos4_bus_target(struct device *dev, unsigned long *_freq, 
	struct platform_device *pdev = container_of(dev, struct platform_device,

						    dev);

	struct busfreq_data *data = platform_get_drvdata(pdev);

	struct opp *opp = devfreq_recommended_opp(dev, _freq, flags);

	unsigned long freq = opp_get_freq(opp);

	unsigned long old_freq = opp_get_freq(data->curr_opp);

	struct opp *opp;

	unsigned long freq;

	unsigned long old_freq = data->curr_oppinfo.rate;

	struct busfreq_opp_info	new_oppinfo;



	if (IS_ERR(opp))

	rcu_read_lock();

	opp = devfreq_recommended_opp(dev, _freq, flags);

	if (IS_ERR(opp)) {

		rcu_read_unlock();

		return PTR_ERR(opp);

	}

	new_oppinfo.rate = opp_get_freq(opp);

	new_oppinfo.volt = opp_get_voltage(opp);

	rcu_read_unlock();

	freq = new_oppinfo.rate;



	if (old_freq == freq)

		return 0;



	dev_dbg(dev, "targetting %lukHz %luuV\n", freq, opp_get_voltage(opp));

	dev_dbg(dev, "targetting %lukHz %luuV\n", freq, new_oppinfo.volt);



	mutex_lock(&data->lock);
@@ -644,17 +666,18 @@ static int exynos4_bus_target(struct device *dev, unsigned long *_freq, 
		goto out;



	if (old_freq < freq)

		err = exynos4_bus_setvolt(data, opp, data->curr_opp);

		err = exynos4_bus_setvolt(data, &new_oppinfo,

					  &data->curr_oppinfo);

	if (err)

		goto out;



	if (old_freq != freq) {

		switch (data->type) {

		case TYPE_BUSF_EXYNOS4210:

			err = exynos4210_set_busclk(data, opp);

			err = exynos4210_set_busclk(data, &new_oppinfo);

			break;

		case TYPE_BUSF_EXYNOS4x12:

			err = exynos4x12_set_busclk(data, opp);

			err = exynos4x12_set_busclk(data, &new_oppinfo);

			break;

		default:

			err = -EINVAL;
@@ -664,11 +687,12 @@ static int exynos4_bus_target(struct device *dev, unsigned long *_freq, 
		goto out;



	if (old_freq > freq)

		err = exynos4_bus_setvolt(data, opp, data->curr_opp);

		err = exynos4_bus_setvolt(data, &new_oppinfo,

					  &data->curr_oppinfo);

	if (err)

		goto out;



	data->curr_opp = opp;

	data->curr_oppinfo = new_oppinfo;

out:

	mutex_unlock(&data->lock);

	return err;
@@ -702,7 +726,7 @@ static int exynos4_bus_get_dev_status(struct device *dev, 


	exynos4_read_ppmu(data);

	busier_dmc = exynos4_get_busier_dmc(data);

	stat->current_frequency = opp_get_freq(data->curr_opp);

	stat->current_frequency = data->curr_oppinfo.rate;



	if (busier_dmc)

		addr = S5P_VA_DMC1;
@@ -933,6 +957,7 @@ static int exynos4_busfreq_pm_notifier_event(struct notifier_block *this, 
	struct busfreq_data *data = container_of(this, struct busfreq_data,

						 pm_notifier);

	struct opp *opp;

	struct busfreq_opp_info	new_oppinfo;

	unsigned long maxfreq = ULONG_MAX;

	int err = 0;
@@ -943,18 +968,29 @@ static int exynos4_busfreq_pm_notifier_event(struct notifier_block *this, 


		data->disabled = true;



		rcu_read_lock();

		opp = opp_find_freq_floor(data->dev, &maxfreq);

		if (IS_ERR(opp)) {

			rcu_read_unlock();

			dev_err(data->dev, "%s: unable to find a min freq\n",

				__func__);

			return PTR_ERR(opp);

		}

		new_oppinfo.rate = opp_get_freq(opp);

		new_oppinfo.volt = opp_get_voltage(opp);

		rcu_read_unlock();



		err = exynos4_bus_setvolt(data, opp, data->curr_opp);

		err = exynos4_bus_setvolt(data, &new_oppinfo,

					  &data->curr_oppinfo);

		if (err)

			goto unlock;



		switch (data->type) {

		case TYPE_BUSF_EXYNOS4210:

			err = exynos4210_set_busclk(data, opp);

			err = exynos4210_set_busclk(data, &new_oppinfo);

			break;

		case TYPE_BUSF_EXYNOS4x12:

			err = exynos4x12_set_busclk(data, opp);

			err = exynos4x12_set_busclk(data, &new_oppinfo);

			break;

		default:

			err = -EINVAL;
@@ -962,7 +998,7 @@ static int exynos4_busfreq_pm_notifier_event(struct notifier_block *this, 
		if (err)

			goto unlock;



		data->curr_opp = opp;

		data->curr_oppinfo = new_oppinfo;

unlock:

		mutex_unlock(&data->lock);

		if (err)
@@ -1027,13 +1063,17 @@ static int exynos4_busfreq_probe(struct platform_device *pdev) 
		}

	}



	rcu_read_lock();

	opp = opp_find_freq_floor(dev, &exynos4_devfreq_profile.initial_freq);

	if (IS_ERR(opp)) {

		rcu_read_unlock();

		dev_err(dev, "Invalid initial frequency %lu kHz.\n",

			exynos4_devfreq_profile.initial_freq);

		return PTR_ERR(opp);

	}

	data->curr_opp = opp;

	data->curr_oppinfo.rate = opp_get_freq(opp);

	data->curr_oppinfo.volt = opp_get_voltage(opp);

	rcu_read_unlock();



	platform_set_drvdata(pdev, data);