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(I'm so sorry!) Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel os linux
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306// SPDX-License-Identifier: GPL-2.0/* * Sample kset and ktype implementation * * Copyright (C) 2004-2007 Greg Kroah-Hartman <greg@kroah.com> * Copyright (C) 2007 Novell Inc. */#include <linux/kobject.h>#include <linux/string.h>#include <linux/sysfs.h>#include <linux/slab.h>#include <linux/module.h>#include <linux/init.h>
/* * This module shows how to create a kset in sysfs called * /sys/kernel/kset_example * Then three kobjects are created and assigned to this kset, "foo", "baz", * and "bar". In those kobjects, attributes of the same name are also * created and if an integer is written to these files, it can be later * read out of it. */
/* * This is our "object" that we will create a few of and register them with * sysfs. */struct foo_obj { struct kobject kobj; int foo; int baz; int bar;};#define to_foo_obj(x) container_of(x, struct foo_obj, kobj)
/* a custom attribute that works just for a struct foo_obj. */struct foo_attribute { struct attribute attr; ssize_t (*show)(struct foo_obj *foo, const struct foo_attribute *attr, char *buf); ssize_t (*store)(struct foo_obj *foo, const struct foo_attribute *attr, const char *buf, size_t count);};#define to_foo_attr(x) container_of_const(x, struct foo_attribute, attr)
/* * The default show function that must be passed to sysfs. This will be * called by sysfs for whenever a show function is called by the user on a * sysfs file associated with the kobjects we have registered. We need to * transpose back from a "default" kobject to our custom struct foo_obj and * then call the show function for that specific object. */static ssize_t foo_attr_show(struct kobject *kobj, struct attribute *attr, char *buf){ const struct foo_attribute *attribute; struct foo_obj *foo;
attribute = to_foo_attr(attr); foo = to_foo_obj(kobj);
if (!attribute->show) return -EIO;
return attribute->show(foo, attribute, buf);}
/* * Just like the default show function above, but this one is for when the * sysfs "store" is requested (when a value is written to a file.) */static ssize_t foo_attr_store(struct kobject *kobj, struct attribute *attr, const char *buf, size_t len){ const struct foo_attribute *attribute; struct foo_obj *foo;
attribute = to_foo_attr(attr); foo = to_foo_obj(kobj);
if (!attribute->store) return -EIO;
return attribute->store(foo, attribute, buf, len);}
/* Our custom sysfs_ops that we will associate with our ktype later on */static const struct sysfs_ops foo_sysfs_ops = { .show = foo_attr_show, .store = foo_attr_store,};
/* * The release function for our object. This is REQUIRED by the kernel to * have. We free the memory held in our object here. * * NEVER try to get away with just a "blank" release function to try to be * smarter than the kernel. Turns out, no one ever is... */static void foo_release(struct kobject *kobj){ struct foo_obj *foo;
foo = to_foo_obj(kobj); kfree(foo);}
/* * The "foo" file where the .foo variable is read from and written to. */static ssize_t foo_show(struct foo_obj *foo_obj, const struct foo_attribute *attr, char *buf){ return sysfs_emit(buf, "%d\n", foo_obj->foo);}
static ssize_t foo_store(struct foo_obj *foo_obj, const struct foo_attribute *attr, const char *buf, size_t count){ int ret;
ret = kstrtoint(buf, 10, &foo_obj->foo); if (ret < 0) return ret;
return count;}
/* Sysfs attributes cannot be world-writable. */static const struct foo_attribute foo_attribute = __ATTR(foo, 0664, foo_show, foo_store);
/* * More complex function where we determine which variable is being accessed by * looking at the attribute for the "baz" and "bar" files. */static ssize_t b_show(struct foo_obj *foo_obj, const struct foo_attribute *attr, char *buf){ int var;
if (strcmp(attr->attr.name, "baz") == 0) var = foo_obj->baz; else var = foo_obj->bar; return sysfs_emit(buf, "%d\n", var);}
static ssize_t b_store(struct foo_obj *foo_obj, const struct foo_attribute *attr, const char *buf, size_t count){ int var, ret;
ret = kstrtoint(buf, 10, &var); if (ret < 0) return ret;
if (strcmp(attr->attr.name, "baz") == 0) foo_obj->baz = var; else foo_obj->bar = var; return count;}
static const struct foo_attribute baz_attribute = __ATTR(baz, 0664, b_show, b_store);static const struct foo_attribute bar_attribute = __ATTR(bar, 0664, b_show, b_store);
/* * Create a group of attributes so that we can create and destroy them all * at once. */static const struct attribute *const foo_default_attrs[] = { &foo_attribute.attr, &baz_attribute.attr, &bar_attribute.attr, NULL, /* need to NULL terminate the list of attributes */};
static umode_t foo_default_attrs_is_visible(struct kobject *kobj, const struct attribute *attr, int n){ /* Hide attributes with the same name as the kobject. */ if (strcmp(kobject_name(kobj), attr->name) == 0) return 0; return attr->mode;}
static const struct attribute_group foo_default_group = { .attrs_const = foo_default_attrs, .is_visible_const = foo_default_attrs_is_visible,};__ATTRIBUTE_GROUPS(foo_default);
/* * Our own ktype for our kobjects. Here we specify our sysfs ops, the * release function, and the set of default attributes we want created * whenever a kobject of this type is registered with the kernel. */static const struct kobj_type foo_ktype = { .sysfs_ops = &foo_sysfs_ops, .release = foo_release, .default_groups = foo_default_groups,};
static struct kset *example_kset;static struct foo_obj *foo_obj;static struct foo_obj *bar_obj;static struct foo_obj *baz_obj;
static struct foo_obj *create_foo_obj(const char *name){ struct foo_obj *foo; int retval;
/* allocate the memory for the whole object */ foo = kzalloc(sizeof(*foo), GFP_KERNEL); if (!foo) return NULL;
/* * As we have a kset for this kobject, we need to set it before calling * the kobject core. */ foo->kobj.kset = example_kset;
/* * Initialize and add the kobject to the kernel. All the default files * will be created here. As we have already specified a kset for this * kobject, we don't have to set a parent for the kobject, the kobject * will be placed beneath that kset automatically. */ retval = kobject_init_and_add(&foo->kobj, &foo_ktype, NULL, "%s", name); if (retval) { kobject_put(&foo->kobj); return NULL; }
/* * We are always responsible for sending the uevent that the kobject * was added to the system. */ kobject_uevent(&foo->kobj, KOBJ_ADD);
return foo;}
static void destroy_foo_obj(struct foo_obj *foo){ kobject_put(&foo->kobj);}
static int __init example_init(void){ /* * Create a kset with the name of "kset_example", * located under /sys/kernel/ */ example_kset = kset_create_and_add("kset_example", NULL, kernel_kobj); if (!example_kset) return -ENOMEM;
/* * Create three objects and register them with our kset */ foo_obj = create_foo_obj("foo"); if (!foo_obj) goto foo_error;
bar_obj = create_foo_obj("bar"); if (!bar_obj) goto bar_error;
baz_obj = create_foo_obj("baz"); if (!baz_obj) goto baz_error;
return 0;
baz_error: destroy_foo_obj(bar_obj);bar_error: destroy_foo_obj(foo_obj);foo_error: kset_unregister(example_kset); return -EINVAL;}
static void __exit example_exit(void){ destroy_foo_obj(baz_obj); destroy_foo_obj(bar_obj); destroy_foo_obj(foo_obj); kset_unregister(example_kset);}
module_init(example_init);module_exit(example_exit);MODULE_DESCRIPTION("Sample kset and ktype implementation");MODULE_LICENSE("GPL v2");MODULE_AUTHOR("Greg Kroah-Hartman <greg@kroah.com>");