[PATCH] sysfs: (rest) if show/store is missing return -EIO

sysfs: fix the rest of the kernel so if an attribute doesn't
       implement show or store method read/write will return
       -EIO instead of 0 or -EINVAL or -EPERM.

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/acpi/scan.c

@@ -65,14 +65,14 @@ static ssize_t acpi_device_attr_show(struct kobject *kobj,
 {
 	struct acpi_device *device = to_acpi_device(kobj);
 	struct acpi_device_attribute *attribute = to_handle_attr(attr);
-	return attribute->show ? attribute->show(device, buf) : 0;
+	return attribute->show ? attribute->show(device, buf) : -EIO;
 }
 static ssize_t acpi_device_attr_store(struct kobject *kobj,
 		struct attribute *attr, const char *buf, size_t len)
 {
 	struct acpi_device *device = to_acpi_device(kobj);
 	struct acpi_device_attribute *attribute = to_handle_attr(attr);
-	return attribute->store ? attribute->store(device, buf, len) : len;
+	return attribute->store ? attribute->store(device, buf, len) : -EIO;
 }
 
 static struct sysfs_ops acpi_device_sysfs_ops = {

drivers/cpufreq/cpufreq.c

@@ -521,7 +521,7 @@ static ssize_t show(struct kobject * kobj, struct attribute * attr ,char * buf)
 	policy = cpufreq_cpu_get(policy->cpu);
 	if (!policy)
 		return -EINVAL;
-	ret = fattr->show ? fattr->show(policy,buf) : 0;
+	ret = fattr->show ? fattr->show(policy,buf) : -EIO;
 	cpufreq_cpu_put(policy);
 	return ret;
 }
@@ -535,7 +535,7 @@ static ssize_t store(struct kobject * kobj, struct attribute * attr,
 	policy = cpufreq_cpu_get(policy->cpu);
 	if (!policy)
 		return -EINVAL;
-	ret = fattr->store ? fattr->store(policy,buf,count) : 0;
+	ret = fattr->store ? fattr->store(policy,buf,count) : -EIO;
 	cpufreq_cpu_put(policy);
 	return ret;
 }

drivers/firmware/edd.c

@@ -115,7 +115,7 @@ edd_attr_show(struct kobject * kobj, struct attribute *attr, char *buf)
 {
 	struct edd_device *dev = to_edd_device(kobj);
 	struct edd_attribute *edd_attr = to_edd_attr(attr);
-	ssize_t ret = 0;
+	ssize_t ret = -EIO;
 
 	if (edd_attr->show)
 		ret = edd_attr->show(dev, buf);

drivers/firmware/efivars.c

@@ -352,7 +352,7 @@ static ssize_t efivar_attr_show(struct kobject *kobj, struct attribute *attr,
 {
 	struct efivar_entry *var = to_efivar_entry(kobj);
 	struct efivar_attribute *efivar_attr = to_efivar_attr(attr);
-	ssize_t ret = 0;
+	ssize_t ret = -EIO;
 
 	if (!capable(CAP_SYS_ADMIN))
 		return -EACCES;
@@ -368,7 +368,7 @@ static ssize_t efivar_attr_store(struct kobject *kobj, struct attribute *attr,
 {
 	struct efivar_entry *var = to_efivar_entry(kobj);
 	struct efivar_attribute *efivar_attr = to_efivar_attr(attr);
-	ssize_t ret = 0;
+	ssize_t ret = -EIO;
 
 	if (!capable(CAP_SYS_ADMIN))
 		return -EACCES;

drivers/infiniband/core/sysfs.c

@@ -71,7 +71,7 @@ static ssize_t port_attr_show(struct kobject *kobj,
 	struct ib_port *p = container_of(kobj, struct ib_port, kobj);
 
 	if (!port_attr->show)
-		return 0;
+		return -EIO;
 
 	return port_attr->show(p, port_attr, buf);
 }

kernel/params.c

@@ -629,7 +629,7 @@ static ssize_t module_attr_show(struct kobject *kobj,
 	mk = to_module_kobject(kobj);
 
 	if (!attribute->show)
-		return -EPERM;
+		return -EIO;
 
 	if (!try_module_get(mk->mod))
 		return -ENODEV;
@@ -653,7 +653,7 @@ static ssize_t module_attr_store(struct kobject *kobj,
 	mk = to_module_kobject(kobj);
 
 	if (!attribute->store)
-		return -EPERM;
+		return -EIO;
 
 	if (!try_module_get(mk->mod))
 		return -ENODEV;

security/seclvl.c

@@ -155,7 +155,7 @@ seclvl_attr_store(struct kobject *kobj,
 	struct seclvl_obj *obj = container_of(kobj, struct seclvl_obj, kobj);
 	struct seclvl_attribute *attribute =
 	    container_of(attr, struct seclvl_attribute, attr);
-	return (attribute->store ? attribute->store(obj, buf, len) : 0);
+	return attribute->store ? attribute->store(obj, buf, len) : -EIO;
 }
 
 static ssize_t
@@ -164,7 +164,7 @@ seclvl_attr_show(struct kobject *kobj, struct attribute *attr, char *buf)
 	struct seclvl_obj *obj = container_of(kobj, struct seclvl_obj, kobj);
 	struct seclvl_attribute *attribute =
 	    container_of(attr, struct seclvl_attribute, attr);
-	return (attribute->show ? attribute->show(obj, buf) : 0);
+	return attribute->show ? attribute->show(obj, buf) : -EIO;
 }
 
 /**