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Subject[PATCH 4.9 244/271] hwmon: (core) Simplify sysfs attribute name allocation
Date
From: Guenter Roeck <linux@roeck-us.net>

commit 3a412d5e4a1c831723d0aaf305f1cf9a78ad9c90 upstream.

Allocating the sysfs attribute name only if needed and only with the
required minimum length looks optimal, but does not take the additional
overhead for both devm_ data structures and the allocation header itself
into account. This also results in unnecessary memory fragmentation.
Move the sysfs name string into struct hwmon_device_attribute and give it
a sufficient length to reduce this overhead.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/hwmon/hwmon.c | 17 +++++++++--------
1 file changed, 9 insertions(+), 8 deletions(-)

--- a/drivers/hwmon/hwmon.c
+++ b/drivers/hwmon/hwmon.c
@@ -38,12 +38,15 @@ struct hwmon_device {

#define to_hwmon_device(d) container_of(d, struct hwmon_device, dev)

+#define MAX_SYSFS_ATTR_NAME_LENGTH 32
+
struct hwmon_device_attribute {
struct device_attribute dev_attr;
const struct hwmon_ops *ops;
enum hwmon_sensor_types type;
u32 attr;
int index;
+ char name[MAX_SYSFS_ATTR_NAME_LENGTH];
};

#define to_hwmon_attr(d) \
@@ -232,20 +235,18 @@ static struct attribute *hwmon_genattr(s
if ((mode & S_IWUGO) && !ops->write)
return ERR_PTR(-EINVAL);

+ hattr = devm_kzalloc(dev, sizeof(*hattr), GFP_KERNEL);
+ if (!hattr)
+ return ERR_PTR(-ENOMEM);
+
if (type == hwmon_chip) {
name = (char *)template;
} else {
- name = devm_kzalloc(dev, strlen(template) + 16, GFP_KERNEL);
- if (!name)
- return ERR_PTR(-ENOMEM);
- scnprintf(name, strlen(template) + 16, template,
+ scnprintf(hattr->name, sizeof(hattr->name), template,
index + hwmon_attr_base(type));
+ name = hattr->name;
}

- hattr = devm_kzalloc(dev, sizeof(*hattr), GFP_KERNEL);
- if (!hattr)
- return ERR_PTR(-ENOMEM);
-
hattr->type = type;
hattr->attr = attr;
hattr->index = index;

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