openwrt/target/linux/ipq806x/patches-5.15/113-v5.19-03-PM-devfreq-Rework-freq_table-to-be-local-to-devfr.patch

From 46d05776a1a5dd8eb479e868f5ff4f4b97d68238 Mon Sep 17 00:00:00 2001
From: Christian 'Ansuel' Marangi <ansuelsmth@gmail.com>
Date: Mon, 6 Jun 2022 12:39:19 +0200
Subject: [PATCH v4 3/4] PM / devfreq: Rework freq_table to be local to devfreq
 struct

Currently we reference the freq_table to the profile defined one and we
make changes on it. Devfreq never supported PROBE_DEFER before the cpu
based scaling support to the passive governor and assumed that a devfreq
device could only had error and be done with it.
Now that a device can PROBE_DEFER a rework to the freq_table logic is
required.

If a device PROBE_DEFER on the GOV_START, the freq_table is already set
in the device profile struct and its init is skipped. This is due to the
fact that it's common for devs to declare this kind of struct static.
This cause the devfreq logic to find a freq table declared (freq_table
not NULL) with random data and poiting to the old addrs freed by devm.

This problem CAN be solved by devs by clearing the freq_table in their
profile struct on driver exit path but it should not be trusted and it
looks to use a flawed logic.

A better solution is to move the freq_table and max_state to the
devfreq struct and never change the profile struct.
This permit to correctly handle PROBE_DEFER since the devfreq struct is
reallocated and contains new values.
Also the profile struct should only be used to init the driver and should
not be used by the devfreq to write the freq_table if it's not provided
by the driver.

Fixes: a03dacb0316f ("PM / devfreq: Add cpu based scaling support to passive governor")
Signed-off-by: Christian 'Ansuel' Marangi <ansuelsmth@gmail.com>
---
 drivers/devfreq/devfreq.c          | 71 ++++++++++++++----------------
 drivers/devfreq/governor_passive.c | 14 +++---
 include/linux/devfreq.h            |  4 ++
 3 files changed, 45 insertions(+), 44 deletions(-)

--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -123,7 +123,7 @@ void devfreq_get_freq_range(struct devfr
 			    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 devfr
 	 * 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
 {
 	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
 
 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
 	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
 
 	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++;
 	}
 
@@ -855,6 +851,9 @@ struct devfreq *devfreq_add_device(struc
 		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);
@@ -890,8 +889,8 @@ struct devfreq *devfreq_add_device(struc
 
 	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);
@@ -900,7 +899,7 @@ struct devfreq *devfreq_add_device(struc
 	}
 
 	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) {
@@ -1658,9 +1657,9 @@ static ssize_t available_frequencies_sho
 
 	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 */
@@ -1683,7 +1682,7 @@ static ssize_t trans_stat_show(struct de
 
 	if (!df->profile)
 		return -EINVAL;
-	max_state = df->profile->max_state;
+	max_state = df->max_state;
 
 	if (max_state == 0)
 		return scnprintf(buf, PAGE_SIZE, "Not Supported.\n");
@@ -1702,7 +1701,7 @@ static ssize_t trans_stat_show(struct de
 		if (len >= PAGE_SIZE - 1)
 			break;
 		len += scnprintf(buf + len, PAGE_SIZE - len, "%10lu",
-				 df->profile->freq_table[i]);
+				 df->freq_table[i]);
 	}
 	if (len >= PAGE_SIZE - 1)
 		return PAGE_SIZE - 1;
@@ -1712,7 +1711,7 @@ static ssize_t trans_stat_show(struct de
 	for (i = 0; i < max_state; i++) {
 		if (len >= PAGE_SIZE - 1)
 			break;
-		if (df->profile->freq_table[i]
+		if (df->freq_table[i]
 					== df->previous_freq) {
 			len += scnprintf(buf + len, PAGE_SIZE - len, "*");
 		} else {
@@ -1722,7 +1721,7 @@ static ssize_t trans_stat_show(struct de
 			break;
 
 		len += scnprintf(buf + len, PAGE_SIZE - len, "%10lu:",
-				 df->profile->freq_table[i]);
+				 df->freq_table[i]);
 		for (j = 0; j < max_state; j++) {
 			if (len >= PAGE_SIZE - 1)
 				break;
@@ -1757,7 +1756,7 @@ static ssize_t trans_stat_store(struct d
 	if (!df->profile)
 		return -EINVAL;
 
-	if (df->profile->max_state == 0)
+	if (df->max_state == 0)
 		return count;
 
 	err = kstrtoint(buf, 10, &value);
@@ -1765,11 +1764,11 @@ static ssize_t trans_stat_store(struct d
 		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);
--- a/drivers/devfreq/governor_passive.c
+++ b/drivers/devfreq/governor_passive.c
@@ -145,18 +145,18 @@ static int get_target_freq_with_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:
--- a/include/linux/devfreq.h
+++ b/include/linux/devfreq.h
@@ -185,6 +185,10 @@ struct devfreq {
 	struct notifier_block nb;
 	struct delayed_work work;
 
+	/* devfreq local freq_table */
+	unsigned long *freq_table;
+	unsigned int max_state;
+
 	unsigned long previous_freq;
 	struct devfreq_dev_status last_status;