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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: Nishanth Menon <nm@ti.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Nishanth Menon 2013-01-18 19:52:35 +00:00 committed by Rafael J. Wysocki
parent bcb27549f4
commit 8fa938acb3
1 changed files with 67 additions and 27 deletions
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94
drivers/devfreq/exynos4_bus.c
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@ -73,6 +73,16 @@ enum busclk_level_idx {
#define EX4210_LV_NUM (LV_2 + 1) #define EX4210_LV_NUM (LV_2 + 1)
#define EX4x12_LV_NUM (LV_4 + 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 { struct busfreq_data {
enum exynos4_busf_type type; enum exynos4_busf_type type;
struct device *dev; struct device *dev;
@ -80,7 +90,7 @@ struct busfreq_data {
bool disabled; bool disabled;
struct regulator *vdd_int; struct regulator *vdd_int;
struct regulator *vdd_mif; /* Exynos4412/4212 only */ struct regulator *vdd_mif; /* Exynos4412/4212 only */
struct opp *curr_opp; struct busfreq_opp_info curr_oppinfo;
struct exynos4_ppmu dmc[2]; struct exynos4_ppmu dmc[2];
struct notifier_block pm_notifier; 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 index;
unsigned int tmp; unsigned int tmp;
for (index = LV_0; index < EX4210_LV_NUM; index++) 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; break;
if (index == EX4210_LV_NUM) if (index == EX4210_LV_NUM)
@ -361,13 +372,14 @@ static int exynos4210_set_busclk(struct busfreq_data *data, struct opp *opp)
return 0; 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 index;
unsigned int tmp; unsigned int tmp;
for (index = LV_0; index < EX4x12_LV_NUM; index++) 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; break;
if (index == EX4x12_LV_NUM) if (index == EX4x12_LV_NUM)
@ -576,11 +588,12 @@ static int exynos4x12_get_intspec(unsigned long mifclk)
return -EINVAL; return -EINVAL;
} }
static int exynos4_bus_setvolt(struct busfreq_data *data, struct opp *opp, static int exynos4_bus_setvolt(struct busfreq_data *data,
struct opp *oldopp) struct busfreq_opp_info *oppi,
struct busfreq_opp_info *oldoppi)
{ {
int err = 0, tmp; int err = 0, tmp;
unsigned long volt = opp_get_voltage(opp); unsigned long volt = oppi->volt;
switch (data->type) { switch (data->type) {
case TYPE_BUSF_EXYNOS4210: case TYPE_BUSF_EXYNOS4210:
@ -595,11 +608,11 @@ static int exynos4_bus_setvolt(struct busfreq_data *data, struct opp *opp,
if (err) if (err)
break; break;
tmp = exynos4x12_get_intspec(opp_get_freq(opp)); tmp = exynos4x12_get_intspec(oppi->rate);
if (tmp < 0) { if (tmp < 0) {
err = tmp; err = tmp;
regulator_set_voltage(data->vdd_mif, regulator_set_voltage(data->vdd_mif,
opp_get_voltage(oldopp), oldoppi->volt,
MAX_SAFEVOLT); MAX_SAFEVOLT);
break; break;
} }
@ -609,7 +622,7 @@ static int exynos4_bus_setvolt(struct busfreq_data *data, struct opp *opp,
/* Try to recover */ /* Try to recover */
if (err) if (err)
regulator_set_voltage(data->vdd_mif, regulator_set_voltage(data->vdd_mif,
opp_get_voltage(oldopp), oldoppi->volt,
MAX_SAFEVOLT); MAX_SAFEVOLT);
break; break;
default: 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, struct platform_device *pdev = container_of(dev, struct platform_device,
dev); dev);
struct busfreq_data *data = platform_get_drvdata(pdev); struct busfreq_data *data = platform_get_drvdata(pdev);
struct opp *opp = devfreq_recommended_opp(dev, _freq, flags); struct opp *opp;
unsigned long freq = opp_get_freq(opp); unsigned long freq;
unsigned long old_freq = opp_get_freq(data->curr_opp); 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); 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) if (old_freq == freq)
return 0; 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); mutex_lock(&data->lock);
@ -644,17 +666,18 @@ static int exynos4_bus_target(struct device *dev, unsigned long *_freq,
goto out; goto out;
if (old_freq < freq) 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) if (err)
goto out; goto out;
if (old_freq != freq) { if (old_freq != freq) {
switch (data->type) { switch (data->type) {
case TYPE_BUSF_EXYNOS4210: case TYPE_BUSF_EXYNOS4210:
err = exynos4210_set_busclk(data, opp); err = exynos4210_set_busclk(data, &new_oppinfo);
break; break;
case TYPE_BUSF_EXYNOS4x12: case TYPE_BUSF_EXYNOS4x12:
err = exynos4x12_set_busclk(data, opp); err = exynos4x12_set_busclk(data, &new_oppinfo);
break; break;
default: default:
err = -EINVAL; err = -EINVAL;
@ -664,11 +687,12 @@ static int exynos4_bus_target(struct device *dev, unsigned long *_freq,
goto out; goto out;
if (old_freq > freq) 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) if (err)
goto out; goto out;
data->curr_opp = opp; data->curr_oppinfo = new_oppinfo;
out: out:
mutex_unlock(&data->lock); mutex_unlock(&data->lock);
return err; return err;
@ -702,7 +726,7 @@ static int exynos4_bus_get_dev_status(struct device *dev,
exynos4_read_ppmu(data); exynos4_read_ppmu(data);
busier_dmc = exynos4_get_busier_dmc(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) if (busier_dmc)
addr = S5P_VA_DMC1; 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, struct busfreq_data *data = container_of(this, struct busfreq_data,
pm_notifier); pm_notifier);
struct opp *opp; struct opp *opp;
struct busfreq_opp_info new_oppinfo;
unsigned long maxfreq = ULONG_MAX; unsigned long maxfreq = ULONG_MAX;
int err = 0; int err = 0;
@ -943,18 +968,29 @@ static int exynos4_busfreq_pm_notifier_event(struct notifier_block *this,
data->disabled = true; data->disabled = true;
rcu_read_lock();
opp = opp_find_freq_floor(data->dev, &maxfreq); 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) if (err)
goto unlock; goto unlock;
switch (data->type) { switch (data->type) {
case TYPE_BUSF_EXYNOS4210: case TYPE_BUSF_EXYNOS4210:
err = exynos4210_set_busclk(data, opp); err = exynos4210_set_busclk(data, &new_oppinfo);
break; break;
case TYPE_BUSF_EXYNOS4x12: case TYPE_BUSF_EXYNOS4x12:
err = exynos4x12_set_busclk(data, opp); err = exynos4x12_set_busclk(data, &new_oppinfo);
break; break;
default: default:
err = -EINVAL; err = -EINVAL;
@ -962,7 +998,7 @@ static int exynos4_busfreq_pm_notifier_event(struct notifier_block *this,
if (err) if (err)
goto unlock; goto unlock;
data->curr_opp = opp; data->curr_oppinfo = new_oppinfo;
unlock: unlock:
mutex_unlock(&data->lock); mutex_unlock(&data->lock);
if (err) 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); opp = opp_find_freq_floor(dev, &exynos4_devfreq_profile.initial_freq);
if (IS_ERR(opp)) { if (IS_ERR(opp)) {
rcu_read_unlock();
dev_err(dev, "Invalid initial frequency %lu kHz.\n", dev_err(dev, "Invalid initial frequency %lu kHz.\n",
exynos4_devfreq_profile.initial_freq); exynos4_devfreq_profile.initial_freq);
return PTR_ERR(opp); 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); platform_set_drvdata(pdev, data);