hwmon: (pmbus) Use krealloc to allocate attribute memory

So far, attribute memory was allocated by pre-calculating the maximum possible
amount of attributes. Not only does this waste memory, it is also risky because
the calculation might be wrong. It also requires a lot of defines to specify
the maximum number of attributes per class.

Allocate attribute memory using krealloc() instead. That means we have to use
kfree(), since devm_krealloc() does not exist, but that is still less costly
and less risky than trying to predict the number of attributes at the beginning.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>

1 files changed, 31 insertions, 109 deletions

diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
index 3782fda21c8b..26b699a6abb9 100644
--- a/drivers/hwmon/pmbus/pmbus_core.c
+++ b/drivers/hwmon/pmbus/pmbus_core.c
@@ -31,39 +31,10 @@
 #include "pmbus.h"
 
 /*
- * Constants needed to determine number of sensors, booleans, and labels.
+ * Number of additional attribute pointers to allocate
+ * with each call to krealloc
  */
-#define PMBUS_MAX_INPUT_SENSORS         22      /* 10*volt, 7*curr, 5*power */
-#define PMBUS_VOUT_SENSORS_PER_PAGE     9       /* input, min, max, lcrit,
-                                                   crit, lowest, highest, avg,
-                                                   reset */
-#define PMBUS_IOUT_SENSORS_PER_PAGE     8       /* input, min, max, crit,
-                                                   lowest, highest, avg,
-                                                   reset */
-#define PMBUS_POUT_SENSORS_PER_PAGE     7       /* input, cap, max, crit,
-                                                 * highest, avg, reset
-                                                 */
-#define PMBUS_MAX_SENSORS_PER_FAN       1       /* input */
-#define PMBUS_MAX_SENSORS_PER_TEMP      9       /* input, min, max, lcrit,
-                                                 * crit, lowest, highest, avg,
-                                                 * reset
-                                                 */
-
-#define PMBUS_MAX_INPUT_BOOLEANS        7       /* v: min_alarm, max_alarm,
-                                                   lcrit_alarm, crit_alarm;
-                                                   c: alarm, crit_alarm;
-                                                   p: crit_alarm */
-#define PMBUS_VOUT_BOOLEANS_PER_PAGE    4       /* min_alarm, max_alarm,
-                                                   lcrit_alarm, crit_alarm */
-#define PMBUS_IOUT_BOOLEANS_PER_PAGE    3       /* alarm, lcrit_alarm,
-                                                   crit_alarm */
-#define PMBUS_POUT_BOOLEANS_PER_PAGE    3       /* cap_alarm, alarm, crit_alarm
-                                                 */
-#define PMBUS_MAX_BOOLEANS_PER_FAN      2       /* alarm, fault */
-#define PMBUS_MAX_BOOLEANS_PER_TEMP     4       /* min_alarm, max_alarm,
-                                                   lcrit_alarm, crit_alarm */
-
-#define PMBUS_MAX_INPUT_LABELS          4       /* vin, vcap, iin, pin */
+#define PMBUS_ATTR_ALLOC_SIZE   32
 
 /*
  * status, status_vout, status_iout, status_fans, status_fan34, and status_temp
@@ -127,7 +98,6 @@ struct pmbus_data {
 
         int max_attributes;
         int num_attributes;
-        struct attribute **attributes;
         struct attribute_group group;
 
         struct pmbus_sensor *sensors;
@@ -790,6 +760,22 @@ static ssize_t pmbus_show_label(struct device *dev,
         return snprintf(buf, PAGE_SIZE, "%s\n", label->label);
 }
 
+static int pmbus_add_attribute(struct pmbus_data *data, struct attribute *attr)
+{
+        if (data->num_attributes >= data->max_attributes - 1) {
+                data->max_attributes += PMBUS_ATTR_ALLOC_SIZE;
+                data->group.attrs = krealloc(data->group.attrs,
+                                             sizeof(struct attribute *) *
+                                             data->max_attributes, GFP_KERNEL);
+                if (data->group.attrs == NULL)
+                        return -ENOMEM;
+        }
+
+        data->group.attrs[data->num_attributes++] = attr;
+        data->group.attrs[data->num_attributes] = NULL;
+        return 0;
+}
+
 static void pmbus_dev_attr_init(struct device_attribute *dev_attr,
                                 const char *name,
                                 umode_t mode,
@@ -831,8 +817,6 @@ static int pmbus_add_boolean(struct pmbus_data *data,
         struct pmbus_boolean *boolean;
         struct sensor_device_attribute *a;
 
-        BUG_ON(data->num_attributes >= data->max_attributes);
-
         boolean = devm_kzalloc(data->dev, sizeof(*boolean), GFP_KERNEL);
         if (!boolean)
                 return -ENOMEM;
@@ -845,9 +829,8 @@ static int pmbus_add_boolean(struct pmbus_data *data,
         boolean->s2 = s2;
         pmbus_attr_init(a, boolean->name, S_IRUGO, pmbus_show_boolean, NULL,
                         (reg << 8) | mask);
-        data->attributes[data->num_attributes++] = &a->dev_attr.attr;
 
-        return 0;
+        return pmbus_add_attribute(data, &a->dev_attr.attr);
 }
 
 static struct pmbus_sensor *pmbus_add_sensor(struct pmbus_data *data,
@@ -859,8 +842,6 @@ static struct pmbus_sensor *pmbus_add_sensor(struct pmbus_data *data,
         struct pmbus_sensor *sensor;
         struct device_attribute *a;
 
-        BUG_ON(data->num_attributes >= data->max_attributes);
-
         sensor = devm_kzalloc(data->dev, sizeof(*sensor), GFP_KERNEL);
         if (!sensor)
                 return NULL;
@@ -876,7 +857,9 @@ static struct pmbus_sensor *pmbus_add_sensor(struct pmbus_data *data,
                             readonly ? S_IRUGO : S_IRUGO | S_IWUSR,
                             pmbus_show_sensor, pmbus_set_sensor);
 
-        data->attributes[data->num_attributes++] = &a->attr;
+        if (pmbus_add_attribute(data, &a->attr))
+                return NULL;
+
         sensor->next = data->sensors;
         data->sensors = sensor;
 
@@ -890,8 +873,6 @@ static int pmbus_add_label(struct pmbus_data *data,
         struct pmbus_label *label;
         struct device_attribute *a;
 
-        BUG_ON(data->num_attributes >= data->max_attributes);
-
         label = devm_kzalloc(data->dev, sizeof(*label), GFP_KERNEL);
         if (!label)
                 return -ENOMEM;
@@ -906,62 +887,7 @@ static int pmbus_add_label(struct pmbus_data *data,
                          index);
 
         pmbus_dev_attr_init(a, label->name, S_IRUGO, pmbus_show_label, NULL);
-        data->attributes[data->num_attributes++] = &a->attr;
-        return 0;
-}
-
-/*
- * Determine maximum number of sensors, booleans, and labels.
- * To keep things simple, only make a rough high estimate.
- */
-static void pmbus_find_max_attr(struct i2c_client *client,
-                                struct pmbus_data *data)
-{
-        const struct pmbus_driver_info *info = data->info;
-        int page, max_sensors, max_booleans, max_labels;
-
-        max_sensors = PMBUS_MAX_INPUT_SENSORS;
-        max_booleans = PMBUS_MAX_INPUT_BOOLEANS;
-        max_labels = PMBUS_MAX_INPUT_LABELS;
-
-        for (page = 0; page < info->pages; page++) {
-                if (info->func[page] & PMBUS_HAVE_VOUT) {
-                        max_sensors += PMBUS_VOUT_SENSORS_PER_PAGE;
-                        max_booleans += PMBUS_VOUT_BOOLEANS_PER_PAGE;
-                        max_labels++;
-                }
-                if (info->func[page] & PMBUS_HAVE_IOUT) {
-                        max_sensors += PMBUS_IOUT_SENSORS_PER_PAGE;
-                        max_booleans += PMBUS_IOUT_BOOLEANS_PER_PAGE;
-                        max_labels++;
-                }
-                if (info->func[page] & PMBUS_HAVE_POUT) {
-                        max_sensors += PMBUS_POUT_SENSORS_PER_PAGE;
-                        max_booleans += PMBUS_POUT_BOOLEANS_PER_PAGE;
-                        max_labels++;
-                }
-                if (info->func[page] & PMBUS_HAVE_FAN12) {
-                        max_sensors += 2 * PMBUS_MAX_SENSORS_PER_FAN;
-                        max_booleans += 2 * PMBUS_MAX_BOOLEANS_PER_FAN;
-                }
-                if (info->func[page] & PMBUS_HAVE_FAN34) {
-                        max_sensors += 2 * PMBUS_MAX_SENSORS_PER_FAN;
-                        max_booleans += 2 * PMBUS_MAX_BOOLEANS_PER_FAN;
-                }
-                if (info->func[page] & PMBUS_HAVE_TEMP) {
-                        max_sensors += PMBUS_MAX_SENSORS_PER_TEMP;
-                        max_booleans += PMBUS_MAX_BOOLEANS_PER_TEMP;
-                }
-                if (info->func[page] & PMBUS_HAVE_TEMP2) {
-                        max_sensors += PMBUS_MAX_SENSORS_PER_TEMP;
-                        max_booleans += PMBUS_MAX_BOOLEANS_PER_TEMP;
-                }
-                if (info->func[page] & PMBUS_HAVE_TEMP3) {
-                        max_sensors += PMBUS_MAX_SENSORS_PER_TEMP;
-                        max_booleans += PMBUS_MAX_BOOLEANS_PER_TEMP;
-                }
-        }
-        data->max_attributes = max_sensors + max_booleans + max_labels;
+        return pmbus_add_attribute(data, &a->attr);
 }
 
 /*
@@ -1709,8 +1635,6 @@ static int pmbus_identify_common(struct i2c_client *client,
                 }
         }
 
-        /* Determine maximum number of sensors, booleans, and labels */
-        pmbus_find_max_attr(client, data);
         pmbus_clear_fault_page(client, 0);
         return 0;
 }
@@ -1770,14 +1694,9 @@ int pmbus_do_probe(struct i2c_client *client, const struct i2c_device_id *id,
                 return ret;
         }
 
-        data->attributes = devm_kzalloc(dev, sizeof(struct attribute *)
-                                        * data->max_attributes, GFP_KERNEL);
-        if (!data->attributes)
-                return -ENOMEM;
-
         ret = pmbus_find_attributes(client, data);
         if (ret)
-                return ret;
+                goto out_kfree;
 
         /*
          * If there are no attributes, something is wrong.
@@ -1785,15 +1704,15 @@ int pmbus_do_probe(struct i2c_client *client, const struct i2c_device_id *id,
          */
         if (!data->num_attributes) {
                 dev_err(dev, "No attributes found\n");
-                return -ENODEV;
+                ret = -ENODEV;
+                goto out_kfree;
         }
 
         /* Register sysfs hooks */
-        data->group.attrs = data->attributes;
         ret = sysfs_create_group(&dev->kobj, &data->group);
         if (ret) {
                 dev_err(dev, "Failed to create sysfs entries\n");
-                return ret;
+                goto out_kfree;
         }
         data->hwmon_dev = hwmon_device_register(dev);
         if (IS_ERR(data->hwmon_dev)) {
@@ -1805,6 +1724,8 @@ int pmbus_do_probe(struct i2c_client *client, const struct i2c_device_id *id,
 
 out_hwmon_device_register:
         sysfs_remove_group(&dev->kobj, &data->group);
+out_kfree:
+        kfree(data->group.attrs);
         return ret;
 }
 EXPORT_SYMBOL_GPL(pmbus_do_probe);
@@ -1814,6 +1735,7 @@ int pmbus_do_remove(struct i2c_client *client)
         struct pmbus_data *data = i2c_get_clientdata(client);
         hwmon_device_unregister(data->hwmon_dev);
         sysfs_remove_group(&client->dev.kobj, &data->group);
+        kfree(data->group.attrs);
         return 0;
 }
 EXPORT_SYMBOL_GPL(pmbus_do_remove);