[PATCH] PM / devfreq: Rework freq_table to be local to devfreq struct

From: Christian Marangi
Date: Sun Jun 19 2022 - 18:04:34 EST

Next message: Christian Marangi: "Re: [PATCH v4 2/4] PM / devfreq: Fix kernel warning with cpufreq passive register fail"
Previous message: kernel test robot: "[morse:mpam/snapshot/v5.18 128/146] drivers/platform/mpam/mpam_resctrl.c:309:25: warning: variable 'dom' is uninitialized when used here"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

On a devfreq PROBE_DEFER, the freq_table in the driver profile struct,
is never reset and may be leaved in an undefined state.

This comes from the fact that we store the freq_table in the driver
profile struct that is commonly defined as static and not reset on
PROBE_DEFER.
We currently skip the reinit of the freq_table if we found
it's already defined since a driver may declare his own freq_table.

This logic is flawed in the case devfreq core generate a freq_table, set
it in the profile struct and then PROBE_DEFER, freeing the freq_table.
In this case devfreq will found a NOT NULL freq_table that has been
freed, skip the freq_table generation and probe the driver based on the
wrong table.

To fix this and correctly handle PROBE_DEFER, use a local freq_table and
max_state in the devfreq struct and never modify the freq_table present
in the profile struct if it does provide it.

Fixes: 0ec09ac2cebe ("PM / devfreq: Set the freq_table of devfreq device")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Christian Marangi <ansuelsmth@xxxxxxxxx>
---
drivers/devfreq/devfreq.c | 71 ++++++++++++++----------------
drivers/devfreq/governor_passive.c | 14 +++---
include/linux/devfreq.h | 5 +++
3 files changed, 46 insertions(+), 44 deletions(-)

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index 01474daf4548..2e2b3b414d67 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -123,7 +123,7 @@ void devfreq_get_freq_range(struct devfreq *devfreq,
unsigned long *min_freq,
unsigned long *max_freq)
{
- unsigned long *freq_table = devfreq->profile->freq_table;
+ unsigned long *freq_table = devfreq->freq_table;
s32 qos_min_freq, qos_max_freq;

lockdep_assert_held(&devfreq->lock);
@@ -133,11 +133,11 @@ void devfreq_get_freq_range(struct devfreq *devfreq,
* The devfreq drivers can initialize this in either ascending or
* descending order and devfreq core supports both.
*/
- if (freq_table[0] < freq_table[devfreq->profile->max_state - 1]) {
+ if (freq_table[0] < freq_table[devfreq->max_state - 1]) {
*min_freq = freq_table[0];
- *max_freq = freq_table[devfreq->profile->max_state - 1];
+ *max_freq = freq_table[devfreq->max_state - 1];
} else {
- *min_freq = freq_table[devfreq->profile->max_state - 1];
+ *min_freq = freq_table[devfreq->max_state - 1];
*max_freq = freq_table[0];
}

@@ -169,8 +169,8 @@ static int devfreq_get_freq_level(struct devfreq *devfreq, unsigned long freq)
{
int lev;

- for (lev = 0; lev < devfreq->profile->max_state; lev++)
- if (freq == devfreq->profile->freq_table[lev])
+ for (lev = 0; lev < devfreq->max_state; lev++)
+ if (freq == devfreq->freq_table[lev])
return lev;

return -EINVAL;
@@ -178,7 +178,6 @@ static int devfreq_get_freq_level(struct devfreq *devfreq, unsigned long freq)

static int set_freq_table(struct devfreq *devfreq)
{
- struct devfreq_dev_profile *profile = devfreq->profile;
struct dev_pm_opp *opp;
unsigned long freq;
int i, count;
@@ -188,25 +187,22 @@ static int set_freq_table(struct devfreq *devfreq)
if (count <= 0)
return -EINVAL;

- profile->max_state = count;
- profile->freq_table = devm_kcalloc(devfreq->dev.parent,
- profile->max_state,
- sizeof(*profile->freq_table),
- GFP_KERNEL);
- if (!profile->freq_table) {
- profile->max_state = 0;
+ devfreq->max_state = count;
+ devfreq->freq_table = devm_kcalloc(devfreq->dev.parent,
+ devfreq->max_state,
+ sizeof(*devfreq->freq_table),
+ GFP_KERNEL);
+ if (!devfreq->freq_table)
return -ENOMEM;
- }

- for (i = 0, freq = 0; i < profile->max_state; i++, freq++) {
+ for (i = 0, freq = 0; i < devfreq->max_state; i++, freq++) {
opp = dev_pm_opp_find_freq_ceil(devfreq->dev.parent, &freq);
if (IS_ERR(opp)) {
- devm_kfree(devfreq->dev.parent, profile->freq_table);
- profile->max_state = 0;
+ devm_kfree(devfreq->dev.parent, devfreq->freq_table);
return PTR_ERR(opp);
}
dev_pm_opp_put(opp);
- profile->freq_table[i] = freq;
+ devfreq->freq_table[i] = freq;
}

return 0;
@@ -246,7 +242,7 @@ int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)

if (lev != prev_lev) {
devfreq->stats.trans_table[
- (prev_lev * devfreq->profile->max_state) + lev]++;
+ (prev_lev * devfreq->max_state) + lev]++;
devfreq->stats.total_trans++;
}

@@ -835,6 +831,9 @@ struct devfreq *devfreq_add_device(struct device *dev,
if (err < 0)
goto err_dev;
mutex_lock(&devfreq->lock);
+ } else {
+ devfreq->freq_table = devfreq->profile->freq_table;
+ devfreq->max_state = devfreq->profile->max_state;
}

devfreq->scaling_min_freq = find_available_min_freq(devfreq);
@@ -870,8 +869,8 @@ struct devfreq *devfreq_add_device(struct device *dev,

devfreq->stats.trans_table = devm_kzalloc(&devfreq->dev,
array3_size(sizeof(unsigned int),
- devfreq->profile->max_state,
- devfreq->profile->max_state),
+ devfreq->max_state,
+ devfreq->max_state),
GFP_KERNEL);
if (!devfreq->stats.trans_table) {
mutex_unlock(&devfreq->lock);
@@ -880,7 +879,7 @@ struct devfreq *devfreq_add_device(struct device *dev,
}

devfreq->stats.time_in_state = devm_kcalloc(&devfreq->dev,
- devfreq->profile->max_state,
+ devfreq->max_state,
sizeof(*devfreq->stats.time_in_state),
GFP_KERNEL);
if (!devfreq->stats.time_in_state) {
@@ -1665,9 +1664,9 @@ static ssize_t available_frequencies_show(struct device *d,

mutex_lock(&df->lock);

- for (i = 0; i < df->profile->max_state; i++)
+ for (i = 0; i < df->max_state; i++)
count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
- "%lu ", df->profile->freq_table[i]);
+ "%lu ", df->freq_table[i]);

mutex_unlock(&df->lock);
/* Truncate the trailing space */
@@ -1690,7 +1689,7 @@ static ssize_t trans_stat_show(struct device *dev,

if (!df->profile)
return -EINVAL;
- max_state = df->profile->max_state;
+ max_state = df->max_state;

if (max_state == 0)
return sprintf(buf, "Not Supported.\n");
@@ -1707,19 +1706,17 @@ static ssize_t trans_stat_show(struct device *dev,
len += sprintf(buf + len, " :");
for (i = 0; i < max_state; i++)
len += sprintf(buf + len, "%10lu",
- df->profile->freq_table[i]);
+ df->freq_table[i]);

len += sprintf(buf + len, " time(ms)\n");

for (i = 0; i < max_state; i++) {
- if (df->profile->freq_table[i]
- == df->previous_freq) {
+ if (df->freq_table[i] == df->previous_freq)
len += sprintf(buf + len, "*");
- } else {
+ else
len += sprintf(buf + len, " ");
- }
- len += sprintf(buf + len, "%10lu:",
- df->profile->freq_table[i]);
+
+ len += sprintf(buf + len, "%10lu:", df->freq_table[i]);
for (j = 0; j < max_state; j++)
len += sprintf(buf + len, "%10u",
df->stats.trans_table[(i * max_state) + j]);
@@ -1743,7 +1740,7 @@ static ssize_t trans_stat_store(struct device *dev,
if (!df->profile)
return -EINVAL;

- if (df->profile->max_state == 0)
+ if (df->max_state == 0)
return count;

err = kstrtoint(buf, 10, &value);
@@ -1751,11 +1748,11 @@ static ssize_t trans_stat_store(struct device *dev,
return -EINVAL;

mutex_lock(&df->lock);
- memset(df->stats.time_in_state, 0, (df->profile->max_state *
+ memset(df->stats.time_in_state, 0, (df->max_state *
sizeof(*df->stats.time_in_state)));
memset(df->stats.trans_table, 0, array3_size(sizeof(unsigned int),
- df->profile->max_state,
- df->profile->max_state));
+ df->max_state,
+ df->max_state));
df->stats.total_trans = 0;
df->stats.last_update = get_jiffies_64();
mutex_unlock(&df->lock);
diff --git a/drivers/devfreq/governor_passive.c b/drivers/devfreq/governor_passive.c
index 72c67979ebe1..ce24a262aa16 100644
--- a/drivers/devfreq/governor_passive.c
+++ b/drivers/devfreq/governor_passive.c
@@ -131,18 +131,18 @@ static int get_target_freq_with_devfreq(struct devfreq *devfreq,
goto out;

/* Use interpolation if required opps is not available */
- for (i = 0; i < parent_devfreq->profile->max_state; i++)
- if (parent_devfreq->profile->freq_table[i] == *freq)
+ for (i = 0; i < parent_devfreq->max_state; i++)
+ if (parent_devfreq->freq_table[i] == *freq)
break;

- if (i == parent_devfreq->profile->max_state)
+ if (i == parent_devfreq->max_state)
return -EINVAL;

- if (i < devfreq->profile->max_state) {
- child_freq = devfreq->profile->freq_table[i];
+ if (i < devfreq->max_state) {
+ child_freq = devfreq->freq_table[i];
} else {
- count = devfreq->profile->max_state;
- child_freq = devfreq->profile->freq_table[count - 1];
+ count = devfreq->max_state;
+ child_freq = devfreq->freq_table[count - 1];
}

out:
diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
index dc10bee75a72..34aab4dd336c 100644
--- a/include/linux/devfreq.h
+++ b/include/linux/devfreq.h
@@ -148,6 +148,8 @@ struct devfreq_stats {
* reevaluate operable frequencies. Devfreq users may use
* devfreq.nb to the corresponding register notifier call chain.
* @work: delayed work for load monitoring.
+ * @freq_table: current frequency table used by the devfreq driver.
+ * @max_state: count of entry present in the frequency table.
* @previous_freq: previously configured frequency value.
* @last_status: devfreq user device info, performance statistics
* @data: Private data of the governor. The devfreq framework does not
@@ -185,6 +187,9 @@ struct devfreq {
struct notifier_block nb;
struct delayed_work work;

+ unsigned long *freq_table;
+ unsigned int max_state;
+
unsigned long previous_freq;
struct devfreq_dev_status last_status;

--
2.36.1

Next message: Christian Marangi: "Re: [PATCH v4 2/4] PM / devfreq: Fix kernel warning with cpufreq passive register fail"
Previous message: kernel test robot: "[morse:mpam/snapshot/v5.18 128/146] drivers/platform/mpam/mpam_resctrl.c:309:25: warning: variable 'dom' is uninitialized when used here"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]