/* * fs/sysfs/file.c - sysfs regular (text) file implementation * * Copyright (c) 2001-3 Patrick Mochel * Copyright (c) 2007 SUSE Linux Products GmbH * Copyright (c) 2007 Tejun Heo <teheo@suse.de> * * This file is released under the GPLv2. * * Please see Documentation/filesystems/sysfs.txt for more information. */ #include <linux/module.h> #include <linux/kobject.h> #include <linux/kallsyms.h> #include <linux/slab.h> #include <linux/list.h> #include <linux/mutex.h> #include <linux/seq_file.h> #include "sysfs.h" #include "../kernfs/kernfs-internal.h" /* * Determine ktype->sysfs_ops for the given kernfs_node. This function * must be called while holding an active reference. */ static const struct sysfs_ops *sysfs_file_ops(struct kernfs_node *kn) { struct kobject *kobj = kn->parent->priv; if (kn->flags & KERNFS_LOCKDEP) lockdep_assert_held(kn); return kobj->ktype ? kobj->ktype->sysfs_ops : NULL; } /* * Reads on sysfs are handled through seq_file, which takes care of hairy * details like buffering and seeking. The following function pipes * sysfs_ops->show() result through seq_file. */ static int sysfs_kf_seq_show(struct seq_file *sf, void *v) { struct kernfs_open_file *of = sf->private; struct kobject *kobj = of->kn->parent->priv; const struct sysfs_ops *ops = sysfs_file_ops(of->kn); ssize_t count; char *buf; /* acquire buffer and ensure that it's >= PAGE_SIZE */ count = seq_get_buf(sf, &buf); if (count < PAGE_SIZE) { seq_commit(sf, -1); return 0; } /* * Invoke show(). Control may reach here via seq file lseek even * if @ops->show() isn't implemented. */ if (ops->show) { count = ops->show(kobj, of->kn->priv, buf); if (count < 0) return count; } /* * The code works fine with PAGE_SIZE return but it's likely to * indicate truncated result or overflow in normal use cases. */ if (count >= (ssize_t)PAGE_SIZE) { print_symbol("fill_read_buffer: %s returned bad count\n", (unsigned long)ops->show); /* Try to struggle along */ count = PAGE_SIZE - 1; } seq_commit(sf, count); return 0; } static ssize_t sysfs_kf_bin_read(struct kernfs_open_file *of, char *buf, size_t count, loff_t pos) { struct bin_attribute *battr = of->kn->priv; struct kobject *kobj = of->kn->parent->priv; loff_t size = file_inode(of->file)->i_size; if (!count) return 0; if (size) { if (pos > size) return 0; if (pos + count > size) count = size - pos; } if (!battr->read) return -EIO; return battr->read(of->file, kobj, battr, buf, pos, count); } /* kernfs write callback for regular sysfs files */ static ssize_t sysfs_kf_write(struct kernfs_open_file *of, char *buf, size_t count, loff_t pos) { const struct sysfs_ops *ops = sysfs_file_ops(of->kn); struct kobject *kobj = of->kn->parent->priv; if (!count) return 0; return ops->store(kobj, of->kn->priv, buf, count); } /* kernfs write callback for bin sysfs files */ static ssize_t sysfs_kf_bin_write(struct kernfs_open_file *of, char *buf, size_t count, loff_t pos) { struct bin_attribute *battr = of->kn->priv; struct kobject *kobj = of->kn->parent->priv; loff_t size = file_inode(of->file)->i_size; if (size) { if (size <= pos) return 0; count = min_t(ssize_t, count, size - pos); } if (!count) return 0; if (!battr->write) return -EIO; return battr->write(of->file, kobj, battr, buf, pos, count); } static int sysfs_kf_bin_mmap(struct kernfs_open_file *of, struct vm_area_struct *vma) { struct bin_attribute *battr = of->kn->priv; struct kobject *kobj = of->kn->parent->priv; return battr->mmap(of->file, kobj, battr, vma); } void sysfs_notify(struct kobject *kobj, const char *dir, const char *attr) { struct kernfs_node *kn = kobj->sd, *tmp; if (kn && dir) kn = kernfs_find_and_get(kn, dir); else kernfs_get(kn); if (kn && attr) { tmp = kernfs_find_and_get(kn, attr); kernfs_put(kn); kn = tmp; } if (kn) { kernfs_notify(kn); kernfs_put(kn); } } EXPORT_SYMBOL_GPL(sysfs_notify); static const struct kernfs_ops sysfs_file_kfops_empty = { }; static const struct kernfs_ops sysfs_file_kfops_ro = { .seq_show = sysfs_kf_seq_show, }; static const struct kernfs_ops sysfs_file_kfops_wo = { .write = sysfs_kf_write, }; static const struct kernfs_ops sysfs_file_kfops_rw = { .seq_show = sysfs_kf_seq_show, .write = sysfs_kf_write, }; static const struct kernfs_ops sysfs_bin_kfops_ro = { .read = sysfs_kf_bin_read, }; static const struct kernfs_ops sysfs_bin_kfops_wo = { .write = sysfs_kf_bin_write, }; static const struct kernfs_ops sysfs_bin_kfops_rw = { .read = sysfs_kf_bin_read, .write = sysfs_kf_bin_write, }; static const struct kernfs_ops sysfs_bin_kfops_mmap = { .read = sysfs_kf_bin_read, .write = sysfs_kf_bin_write, .mmap = sysfs_kf_bin_mmap, }; int sysfs_add_file_mode_ns(struct kernfs_node *parent, const struct attribute *attr, bool is_bin, umode_t mode, const void *ns) { struct lock_class_key *key = NULL; const struct kernfs_ops *ops; struct kernfs_node *kn; loff_t size; if (!is_bin) { struct kobject *kobj = parent->priv; const struct sysfs_ops *sysfs_ops = kobj->ktype->sysfs_ops; /* every kobject with an attribute needs a ktype assigned */ if (WARN(!sysfs_ops, KERN_ERR "missing sysfs attribute operations for kobject: %s\n", kobject_name(kobj))) return -EINVAL; if (sysfs_ops->show && sysfs_ops->store) ops = &sysfs_file_kfops_rw; else if (sysfs_ops->show) ops = &sysfs_file_kfops_ro; else if (sysfs_ops->store) ops = &sysfs_file_kfops_wo; else ops = &sysfs_file_kfops_empty; size = PAGE_SIZE; } else { struct bin_attribute *battr = (void *)attr; if (battr->mmap) ops = &sysfs_bin_kfops_mmap; else if (battr->read && battr->write) ops = &sysfs_bin_kfops_rw; else if (battr->read) ops = &sysfs_bin_kfops_ro; else if (battr->write) ops = &sysfs_bin_kfops_wo; else ops = &sysfs_file_kfops_empty; size = battr->size; } #ifdef CONFIG_DEBUG_LOCK_ALLOC if (!attr->ignore_lockdep) key = attr->key ?: (struct lock_class_key *)&attr->skey; #endif kn = __kernfs_create_file(parent, attr->name, mode, size, ops, (void *)attr, ns, true, key); if (IS_ERR(kn)) { if (PTR_ERR(kn) == -EEXIST) sysfs_warn_dup(parent, attr->name); return PTR_ERR(kn); } return 0; } int sysfs_add_file(struct kernfs_node *parent, const struct attribute *attr, bool is_bin) { return sysfs_add_file_mode_ns(parent, attr, is_bin, attr->mode, NULL); } /** * sysfs_create_file_ns - create an attribute file for an object with custom ns * @kobj: object we're creating for * @attr: attribute descriptor * @ns: namespace the new file should belong to */ int sysfs_create_file_ns(struct kobject *kobj, const struct attribute *attr, const void *ns) { BUG_ON(!kobj || !kobj->sd || !attr); return sysfs_add_file_mode_ns(kobj->sd, attr, false, attr->mode, ns); } EXPORT_SYMBOL_GPL(sysfs_create_file_ns); int sysfs_create_files(struct kobject *kobj, const struct attribute **ptr) { int err = 0; int i; for (i = 0; ptr[i] && !err; i++) err = sysfs_create_file(kobj, ptr[i]); if (err) while (--i >= 0) sysfs_remove_file(kobj, ptr[i]); return err; } EXPORT_SYMBOL_GPL(sysfs_create_files); /** * sysfs_add_file_to_group - add an attribute file to a pre-existing group. * @kobj: object we're acting for. * @attr: attribute descriptor. * @group: group name. */ int sysfs_add_file_to_group(struct kobject *kobj, const struct attribute *attr, const char *group) { struct kernfs_node *parent; int error; if (group) { parent = kernfs_find_and_get(kobj->sd, group); } else { parent = kobj->sd; kernfs_get(parent); } if (!parent) return -ENOENT; error = sysfs_add_file(parent, attr, false); kernfs_put(parent); return error; } EXPORT_SYMBOL_GPL(sysfs_add_file_to_group); /** * sysfs_chmod_file - update the modified mode value on an object attribute. * @kobj: object we're acting for. * @attr: attribute descriptor. * @mode: file permissions. * */ int sysfs_chmod_file(struct kobject *kobj, const struct attribute *attr, umode_t mode) { struct kernfs_node *kn; struct iattr newattrs; int rc; kn = kernfs_find_and_get(kobj->sd, attr->name); if (!kn) return -ENOENT; newattrs.ia_mode = (mode & S_IALLUGO) | (kn->mode & ~S_IALLUGO); newattrs.ia_valid = ATTR_MODE; rc = kernfs_setattr(kn, &newattrs); kernfs_put(kn); return rc; } EXPORT_SYMBOL_GPL(sysfs_chmod_file); /** * sysfs_remove_file_ns - remove an object attribute with a custom ns tag * @kobj: object we're acting for * @attr: attribute descriptor * @ns: namespace tag of the file to remove * * Hash the attribute name and namespace tag and kill the victim. */ void sysfs_remove_file_ns(struct kobject *kobj, const struct attribute *attr, const void *ns) { struct kernfs_node *parent = kobj->sd; kernfs_remove_by_name_ns(parent, attr->name, ns); } EXPORT_SYMBOL_GPL(sysfs_remove_file_ns); /** * sysfs_remove_file_self - remove an object attribute from its own method * @kobj: object we're acting for * @attr: attribute descriptor * * See kernfs_remove_self() for details. */ bool sysfs_remove_file_self(struct kobject *kobj, const struct attribute *attr) { struct kernfs_node *parent = kobj->sd; struct kernfs_node *kn; bool ret; kn = kernfs_find_and_get(parent, attr->name); if (WARN_ON_ONCE(!kn)) return false; ret = kernfs_remove_self(kn); kernfs_put(kn); return ret; } void sysfs_remove_files(struct kobject *kobj, const struct attribute **ptr) { int i; for (i = 0; ptr[i]; i++) sysfs_remove_file(kobj, ptr[i]); } EXPORT_SYMBOL_GPL(sysfs_remove_files); /** * sysfs_remove_file_from_group - remove an attribute file from a group. * @kobj: object we're acting for. * @attr: attribute descriptor. * @group: group name. */ void sysfs_remove_file_from_group(struct kobject *kobj, const struct attribute *attr, const char *group) { struct kernfs_node *parent; if (group) { parent = kernfs_find_and_get(kobj->sd, group); } else { parent = kobj->sd; kernfs_get(parent); } if (parent) { kernfs_remove_by_name(parent, attr->name); kernfs_put(parent); } } EXPORT_SYMBOL_GPL(sysfs_remove_file_from_group); /** * sysfs_create_bin_file - create binary file for object. * @kobj: object. * @attr: attribute descriptor. */ int sysfs_create_bin_file(struct kobject *kobj, const struct bin_attribute *attr) { BUG_ON(!kobj || !kobj->sd || !attr); return sysfs_add_file(kobj->sd, &attr->attr, true); } EXPORT_SYMBOL_GPL(sysfs_create_bin_file); /** * sysfs_remove_bin_file - remove binary file for object. * @kobj: object. * @attr: attribute descriptor. */ void sysfs_remove_bin_file(struct kobject *kobj, const struct bin_attribute *attr) { kernfs_remove_by_name(kobj->sd, attr->attr.name); } EXPORT_SYMBOL_GPL(sysfs_remove_bin_file);