ACPI: configfs: Make get_header() to return error pointer

Instead of duplicating error codes here and there,
make get_header() to return error pointer.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/acpi_configfs.c

@@ -70,7 +70,7 @@ static inline struct acpi_table_header *get_header(struct config_item *cfg)
 	if (!table->header)
 		pr_err("table not loaded\n");
 
-	return table->header;
+	return table->header ?: ERR_PTR(-EINVAL);
 }
 
 static ssize_t acpi_table_aml_read(struct config_item *cfg,
@@ -78,8 +78,8 @@ static ssize_t acpi_table_aml_read(struct config_item *cfg,
 {
 	struct acpi_table_header *h = get_header(cfg);
 
-	if (!h)
-		return -EINVAL;
+	if (IS_ERR(h))
+		return PTR_ERR(h);
 
 	if (data)
 		memcpy(data, h, h->length);
@@ -100,8 +100,8 @@ static ssize_t acpi_table_signature_show(struct config_item *cfg, char *str)
 {
 	struct acpi_table_header *h = get_header(cfg);
 
-	if (!h)
-		return -EINVAL;
+	if (IS_ERR(h))
+		return PTR_ERR(h);
 
 	return sysfs_emit(str, "%.*s\n", ACPI_NAMESEG_SIZE, h->signature);
 }
@@ -110,8 +110,8 @@ static ssize_t acpi_table_length_show(struct config_item *cfg, char *str)
 {
 	struct acpi_table_header *h = get_header(cfg);
 
-	if (!h)
-		return -EINVAL;
+	if (IS_ERR(h))
+		return PTR_ERR(h);
 
 	return sysfs_emit(str, "%d\n", h->length);
 }
@@ -120,8 +120,8 @@ static ssize_t acpi_table_revision_show(struct config_item *cfg, char *str)
 {
 	struct acpi_table_header *h = get_header(cfg);
 
-	if (!h)
-		return -EINVAL;
+	if (IS_ERR(h))
+		return PTR_ERR(h);
 
 	return sysfs_emit(str, "%d\n", h->revision);
 }
@@ -130,8 +130,8 @@ static ssize_t acpi_table_oem_id_show(struct config_item *cfg, char *str)
 {
 	struct acpi_table_header *h = get_header(cfg);
 
-	if (!h)
-		return -EINVAL;
+	if (IS_ERR(h))
+		return PTR_ERR(h);
 
 	return sysfs_emit(str, "%.*s\n", ACPI_OEM_ID_SIZE, h->oem_id);
 }
@@ -140,8 +140,8 @@ static ssize_t acpi_table_oem_table_id_show(struct config_item *cfg, char *str)
 {
 	struct acpi_table_header *h = get_header(cfg);
 
-	if (!h)
-		return -EINVAL;
+	if (IS_ERR(h))
+		return PTR_ERR(h);
 
 	return sysfs_emit(str, "%.*s\n", ACPI_OEM_TABLE_ID_SIZE, h->oem_table_id);
 }
@@ -150,8 +150,8 @@ static ssize_t acpi_table_oem_revision_show(struct config_item *cfg, char *str)
 {
 	struct acpi_table_header *h = get_header(cfg);
 
-	if (!h)
-		return -EINVAL;
+	if (IS_ERR(h))
+		return PTR_ERR(h);
 
 	return sysfs_emit(str, "%d\n", h->oem_revision);
 }
@@ -161,8 +161,8 @@ static ssize_t acpi_table_asl_compiler_id_show(struct config_item *cfg,
 {
 	struct acpi_table_header *h = get_header(cfg);
 
-	if (!h)
-		return -EINVAL;
+	if (IS_ERR(h))
+		return PTR_ERR(h);
 
 	return sysfs_emit(str, "%.*s\n", ACPI_NAMESEG_SIZE, h->asl_compiler_id);
 }
@@ -172,8 +172,8 @@ static ssize_t acpi_table_asl_compiler_revision_show(struct config_item *cfg,
 {
 	struct acpi_table_header *h = get_header(cfg);
 
-	if (!h)
-		return -EINVAL;
+	if (IS_ERR(h))
+		return PTR_ERR(h);
 
 	return sysfs_emit(str, "%d\n", h->asl_compiler_revision);
 }