diff --git a/drivers/s390/cio/ccwgroup.c b/drivers/s390/cio/ccwgroup.c
index fe1ad1722158..85b2e51a42ae 100644
--- a/drivers/s390/cio/ccwgroup.c
+++ b/drivers/s390/cio/ccwgroup.c
@@ -318,7 +318,7 @@ ccwgroup_online_store (struct device *dev, struct device_attribute *attr, const
 {
 	struct ccwgroup_device *gdev;
 	struct ccwgroup_driver *gdrv;
-	unsigned int value;
+	unsigned long value;
 	int ret;
 
 	gdev = to_ccwgroupdev(dev);
@@ -329,7 +329,9 @@ ccwgroup_online_store (struct device *dev, struct device_attribute *attr, const
 	if (!try_module_get(gdrv->owner))
 		return -EINVAL;
 
-	value = simple_strtoul(buf, NULL, 0);
+	ret = strict_strtoul(buf, 0, &value);
+	if (ret)
+		goto out;
 	ret = count;
 	if (value == 1)
 		ccwgroup_set_online(gdev);
@@ -337,6 +339,7 @@ ccwgroup_online_store (struct device *dev, struct device_attribute *attr, const
 		ccwgroup_set_offline(gdev);
 	else
 		ret = -EINVAL;
+out:
 	module_put(gdrv->owner);
 	return ret;
 }
diff --git a/drivers/s390/cio/cmf.c b/drivers/s390/cio/cmf.c
index f4c132ab39ed..2808b6833b9e 100644
--- a/drivers/s390/cio/cmf.c
+++ b/drivers/s390/cio/cmf.c
@@ -1219,16 +1219,21 @@ static ssize_t cmb_enable_store(struct device *dev,
 {
 	struct ccw_device *cdev;
 	int ret;
+	unsigned long val;
+
+	ret = strict_strtoul(buf, 16, &val);
+	if (ret)
+		return ret;
 
 	cdev = to_ccwdev(dev);
 
-	switch (buf[0]) {
-	case '0':
+	switch (val) {
+	case 0:
 		ret = disable_cmf(cdev);
 		if (ret)
 			dev_info(&cdev->dev, "disable_cmf failed (%d)\n", ret);
 		break;
-	case '1':
+	case 1:
 		ret = enable_cmf(cdev);
 		if (ret && ret != -EBUSY)
 			dev_info(&cdev->dev, "enable_cmf failed (%d)\n", ret);
diff --git a/drivers/s390/cio/css.c b/drivers/s390/cio/css.c
index c1afab5f72d6..595e327d2f76 100644
--- a/drivers/s390/cio/css.c
+++ b/drivers/s390/cio/css.c
@@ -705,13 +705,17 @@ css_cm_enable_store(struct device *dev, struct device_attribute *attr,
 {
 	struct channel_subsystem *css = to_css(dev);
 	int ret;
+	unsigned long val;
 
+	ret = strict_strtoul(buf, 16, &val);
+	if (ret)
+		return ret;
 	mutex_lock(&css->mutex);
-	switch (buf[0]) {
-	case '0':
+	switch (val) {
+	case 0:
 		ret = css->cm_enabled ? chsc_secm(css, 0) : 0;
 		break;
-	case '1':
+	case 1:
 		ret = css->cm_enabled ? 0 : chsc_secm(css, 1);
 		break;
 	default:
diff --git a/drivers/s390/cio/device.c b/drivers/s390/cio/device.c
index e0c7adb8958e..abfd601d237a 100644
--- a/drivers/s390/cio/device.c
+++ b/drivers/s390/cio/device.c
@@ -512,8 +512,8 @@ static ssize_t online_store (struct device *dev, struct device_attribute *attr,
 			     const char *buf, size_t count)
 {
 	struct ccw_device *cdev = to_ccwdev(dev);
-	int i, force;
-	char *tmp;
+	int force, ret;
+	unsigned long i;
 
 	if (atomic_cmpxchg(&cdev->private->onoff, 0, 1) != 0)
 		return -EAGAIN;
@@ -525,25 +525,30 @@ static ssize_t online_store (struct device *dev, struct device_attribute *attr,
 	if (!strncmp(buf, "force\n", count)) {
 		force = 1;
 		i = 1;
+		ret = 0;
 	} else {
 		force = 0;
-		i = simple_strtoul(buf, &tmp, 16);
+		ret = strict_strtoul(buf, 16, &i);
 	}
-
+	if (ret)
+		goto out;
 	switch (i) {
 	case 0:
 		online_store_handle_offline(cdev);
+		ret = count;
 		break;
 	case 1:
 		online_store_handle_online(cdev, force);
+		ret = count;
 		break;
 	default:
-		count = -EINVAL;
+		ret = -EINVAL;
 	}
+out:
 	if (cdev->drv)
 		module_put(cdev->drv->owner);
 	atomic_set(&cdev->private->onoff, 0);
-	return count;
+	return ret;
 }
 
 static ssize_t
diff --git a/drivers/s390/cio/qdio.c b/drivers/s390/cio/qdio.c
index 43876e287370..445cf364e461 100644
--- a/drivers/s390/cio/qdio.c
+++ b/drivers/s390/cio/qdio.c
@@ -3663,11 +3663,11 @@ qdio_performance_stats_show(struct bus_type *bus, char *buf)
 static ssize_t
 qdio_performance_stats_store(struct bus_type *bus, const char *buf, size_t count)
 {
-	char *tmp;
-	int i;
+	unsigned long i;
+	int ret;
 
-	i = simple_strtoul(buf, &tmp, 16);
-	if ((i == 0) || (i == 1)) {
+	ret = strict_strtoul(buf, 16, &i);
+	if (!ret && ((i == 0) || (i == 1))) {
 		if (i == qdio_performance_stats)
 			return count;
 		qdio_performance_stats = i;