add new system file

hc

2024-02-20 102a0743326a03cd1a1202ceda21e175b7d3575c

 kernel/drivers/base/class.c
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@@ -8,6 +8,7 @@
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  * Copyright (c) 2003-2004 IBM Corp.
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  */
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+#include <linux/device/class.h>
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 #include <linux/device.h>
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 #include <linux/module.h>
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 #include <linux/init.h>
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@@ -117,16 +118,22 @@
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 		kset_put(&cls->p->subsys);
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 }
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+static struct device *klist_class_to_dev(struct klist_node *n)
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+{
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+	struct device_private *p = to_device_private_class(n);
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+	return p->device;
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+}
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+
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 static void klist_class_dev_get(struct klist_node *n)
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 {
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-	struct device *dev = container_of(n, struct device, knode_class);
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+	struct device *dev = klist_class_to_dev(n);
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 	get_device(dev);
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 }
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 static void klist_class_dev_put(struct klist_node *n)
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 {
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-	struct device *dev = container_of(n, struct device, knode_class);
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+	struct device *dev = klist_class_to_dev(n);
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 	put_device(dev);
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 }
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@@ -185,6 +192,11 @@
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 	}
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 	error = class_add_groups(class_get(cls), cls->class_groups);
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 	class_put(cls);
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+	if (error) {
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+		kobject_del(&cp->subsys.kobj);
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+		kfree_const(cp->subsys.kobj.name);
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+		kfree(cp);
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+	}
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 	return error;
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 }
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 EXPORT_SYMBOL_GPL(__class_register);
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@@ -277,7 +289,7 @@
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 	struct klist_node *start_knode = NULL;
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 	if (start)
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-		start_knode = &start->knode_class;
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+		start_knode = &start->p->knode_class;
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 	klist_iter_init_node(&class->p->klist_devices, &iter->ki, start_knode);
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 	iter->type = type;
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 }
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@@ -304,7 +316,7 @@
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 		knode = klist_next(&iter->ki);
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 		if (!knode)
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 			return NULL;
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-		dev = container_of(knode, struct device, knode_class);
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+		dev = klist_class_to_dev(knode);
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 		if (!iter->type || iter->type == dev->type)
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 			return dev;
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 	}
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@@ -471,7 +483,7 @@
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 	struct class_attribute_string *cs;
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 	cs = container_of(attr, struct class_attribute_string, attr);
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-	return snprintf(buf, PAGE_SIZE, "%s\n", cs->str);
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+	return sysfs_emit(buf, "%s\n", cs->str);
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 }
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 EXPORT_SYMBOL_GPL(show_class_attr_string);