v4.19.13 snapshot.
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
new file mode 100644
index 0000000..0a7252a
--- /dev/null
+++ b/fs/sysfs/file.c
@@ -0,0 +1,558 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * 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>
+ *
+ * Please see Documentation/filesystems/sysfs.txt for more information.
+ */
+
+#include <linux/module.h>
+#include <linux/kobject.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 and clear */
+ count = seq_get_buf(sf, &buf);
+ if (count < PAGE_SIZE) {
+ seq_commit(sf, -1);
+ return 0;
+ }
+ memset(buf, 0, PAGE_SIZE);
+
+ /*
+ * 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) {
+ printk("fill_read_buffer: %pS returned bad count\n",
+ 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 read callback for regular sysfs files with pre-alloc */
+static ssize_t sysfs_kf_read(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;
+ ssize_t len;
+
+ /*
+ * If buf != of->prealloc_buf, we don't know how
+ * large it is, so cannot safely pass it to ->show
+ */
+ if (WARN_ON_ONCE(buf != of->prealloc_buf))
+ return 0;
+ len = ops->show(kobj, of->kn->priv, buf);
+ if (len < 0)
+ return len;
+ if (pos) {
+ if (len <= pos)
+ return 0;
+ len -= pos;
+ memmove(buf, buf + pos, len);
+ }
+ return min_t(ssize_t, count, len);
+}
+
+/* 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 -EFBIG;
+ 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_prealloc_kfops_ro = {
+ .read = sysfs_kf_read,
+ .prealloc = true,
+};
+
+static const struct kernfs_ops sysfs_prealloc_kfops_wo = {
+ .write = sysfs_kf_write,
+ .prealloc = true,
+};
+
+static const struct kernfs_ops sysfs_prealloc_kfops_rw = {
+ .read = sysfs_kf_read,
+ .write = sysfs_kf_write,
+ .prealloc = true,
+};
+
+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, kuid_t uid, kgid_t gid, 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) {
+ if (mode & SYSFS_PREALLOC)
+ ops = &sysfs_prealloc_kfops_rw;
+ else
+ ops = &sysfs_file_kfops_rw;
+ } else if (sysfs_ops->show) {
+ if (mode & SYSFS_PREALLOC)
+ ops = &sysfs_prealloc_kfops_ro;
+ else
+ ops = &sysfs_file_kfops_ro;
+ } else if (sysfs_ops->store) {
+ if (mode & SYSFS_PREALLOC)
+ ops = &sysfs_prealloc_kfops_wo;
+ else
+ 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 & 0777, uid, gid,
+ size, ops, (void *)attr, ns, key);
+ if (IS_ERR(kn)) {
+ if (PTR_ERR(kn) == -EEXIST)
+ sysfs_warn_dup(parent, attr->name);
+ return PTR_ERR(kn);
+ }
+ return 0;
+}
+
+/**
+ * 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)
+{
+ kuid_t uid;
+ kgid_t gid;
+
+ BUG_ON(!kobj || !kobj->sd || !attr);
+
+ kobject_get_ownership(kobj, &uid, &gid);
+ return sysfs_add_file_mode_ns(kobj->sd, attr, false, attr->mode,
+ uid, gid, 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;
+ kuid_t uid;
+ kgid_t gid;
+ int error;
+
+ if (group) {
+ parent = kernfs_find_and_get(kobj->sd, group);
+ } else {
+ parent = kobj->sd;
+ kernfs_get(parent);
+ }
+
+ if (!parent)
+ return -ENOENT;
+
+ kobject_get_ownership(kobj, &uid, &gid);
+ error = sysfs_add_file_mode_ns(parent, attr, false,
+ attr->mode, uid, gid, NULL);
+ 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_break_active_protection - break "active" protection
+ * @kobj: The kernel object @attr is associated with.
+ * @attr: The attribute to break the "active" protection for.
+ *
+ * With sysfs, just like kernfs, deletion of an attribute is postponed until
+ * all active .show() and .store() callbacks have finished unless this function
+ * is called. Hence this function is useful in methods that implement self
+ * deletion.
+ */
+struct kernfs_node *sysfs_break_active_protection(struct kobject *kobj,
+ const struct attribute *attr)
+{
+ struct kernfs_node *kn;
+
+ kobject_get(kobj);
+ kn = kernfs_find_and_get(kobj->sd, attr->name);
+ if (kn)
+ kernfs_break_active_protection(kn);
+ return kn;
+}
+EXPORT_SYMBOL_GPL(sysfs_break_active_protection);
+
+/**
+ * sysfs_unbreak_active_protection - restore "active" protection
+ * @kn: Pointer returned by sysfs_break_active_protection().
+ *
+ * Undo the effects of sysfs_break_active_protection(). Since this function
+ * calls kernfs_put() on the kernfs node that corresponds to the 'attr'
+ * argument passed to sysfs_break_active_protection() that attribute may have
+ * been removed between the sysfs_break_active_protection() and
+ * sysfs_unbreak_active_protection() calls, it is not safe to access @kn after
+ * this function has returned.
+ */
+void sysfs_unbreak_active_protection(struct kernfs_node *kn)
+{
+ struct kobject *kobj = kn->parent->priv;
+
+ kernfs_unbreak_active_protection(kn);
+ kernfs_put(kn);
+ kobject_put(kobj);
+}
+EXPORT_SYMBOL_GPL(sysfs_unbreak_active_protection);
+
+/**
+ * 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)
+{
+ kuid_t uid;
+ kgid_t gid;
+
+ BUG_ON(!kobj || !kobj->sd || !attr);
+
+ kobject_get_ownership(kobj, &uid, &gid);
+ return sysfs_add_file_mode_ns(kobj->sd, &attr->attr, true,
+ attr->attr.mode, uid, gid, NULL);
+}
+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);