/*
- * file.c - operations for regular (text) files.
+ * 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/fsnotify.h>
#include <linux/kobject.h>
#include <linux/namei.h>
#include <linux/poll.h>
#include <linux/list.h>
+#include <linux/mutex.h>
#include <asm/uaccess.h>
-#include <asm/semaphore.h>
#include "sysfs.h"
-#define to_sattr(a) container_of(a,struct subsys_attribute, attr)
-
/*
- * Subsystem file operations.
- * These operations allow subsystems to have files that can be
- * read/written.
+ * There's one sysfs_buffer for each open file and one
+ * sysfs_open_dirent for each sysfs_dirent with one or more open
+ * files.
+ *
+ * filp->private_data points to sysfs_buffer and
+ * sysfs_dirent->s_attr.open points to sysfs_open_dirent. s_attr.open
+ * is protected by sysfs_open_dirent_lock.
*/
-static ssize_t
-subsys_attr_show(struct kobject * kobj, struct attribute * attr, char * page)
-{
- struct kset *kset = to_kset(kobj);
- struct subsys_attribute * sattr = to_sattr(attr);
- ssize_t ret = -EIO;
-
- if (sattr->show)
- ret = sattr->show(kset, page);
- return ret;
-}
-
-static ssize_t
-subsys_attr_store(struct kobject * kobj, struct attribute * attr,
- const char * page, size_t count)
-{
- struct kset *kset = to_kset(kobj);
- struct subsys_attribute * sattr = to_sattr(attr);
- ssize_t ret = -EIO;
-
- if (sattr->store)
- ret = sattr->store(kset, page, count);
- return ret;
-}
+static DEFINE_SPINLOCK(sysfs_open_dirent_lock);
-static struct sysfs_ops subsys_sysfs_ops = {
- .show = subsys_attr_show,
- .store = subsys_attr_store,
+struct sysfs_open_dirent {
+ atomic_t refcnt;
+ atomic_t event;
+ wait_queue_head_t poll;
+ struct list_head buffers; /* goes through sysfs_buffer.list */
};
struct sysfs_buffer {
loff_t pos;
char * page;
struct sysfs_ops * ops;
- struct semaphore sem;
+ struct mutex mutex;
int needs_read_fill;
int event;
+ struct list_head list;
};
/**
static int fill_read_buffer(struct dentry * dentry, struct sysfs_buffer * buffer)
{
struct sysfs_dirent *attr_sd = dentry->d_fsdata;
- struct kobject *kobj = attr_sd->s_parent->s_elem.dir.kobj;
+ struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
struct sysfs_ops * ops = buffer->ops;
int ret = 0;
ssize_t count;
if (!sysfs_get_active_two(attr_sd))
return -ENODEV;
- buffer->event = atomic_read(&attr_sd->s_event);
- count = ops->show(kobj, attr_sd->s_elem.attr.attr, buffer->page);
+ buffer->event = atomic_read(&attr_sd->s_attr.open->event);
+ count = ops->show(kobj, attr_sd->s_attr.attr, buffer->page);
sysfs_put_active_two(attr_sd);
- BUG_ON(count > (ssize_t)PAGE_SIZE);
+ /*
+ * The code works fine with PAGE_SIZE return but it's likely to
+ * indicate truncated result or overflow in normal use cases.
+ */
+ BUG_ON(count >= (ssize_t)PAGE_SIZE);
if (count >= 0) {
buffer->needs_read_fill = 0;
buffer->count = count;
struct sysfs_buffer * buffer = file->private_data;
ssize_t retval = 0;
- down(&buffer->sem);
+ mutex_lock(&buffer->mutex);
if (buffer->needs_read_fill) {
retval = fill_read_buffer(file->f_path.dentry,buffer);
if (retval)
retval = simple_read_from_buffer(buf, count, ppos, buffer->page,
buffer->count);
out:
- up(&buffer->sem);
+ mutex_unlock(&buffer->mutex);
return retval;
}
flush_write_buffer(struct dentry * dentry, struct sysfs_buffer * buffer, size_t count)
{
struct sysfs_dirent *attr_sd = dentry->d_fsdata;
- struct kobject *kobj = attr_sd->s_parent->s_elem.dir.kobj;
+ struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
struct sysfs_ops * ops = buffer->ops;
int rc;
if (!sysfs_get_active_two(attr_sd))
return -ENODEV;
- rc = ops->store(kobj, attr_sd->s_elem.attr.attr, buffer->page, count);
+ rc = ops->store(kobj, attr_sd->s_attr.attr, buffer->page, count);
sysfs_put_active_two(attr_sd);
struct sysfs_buffer * buffer = file->private_data;
ssize_t len;
- down(&buffer->sem);
+ mutex_lock(&buffer->mutex);
len = fill_write_buffer(buffer, buf, count);
if (len > 0)
len = flush_write_buffer(file->f_path.dentry, buffer, len);
if (len > 0)
*ppos += len;
- up(&buffer->sem);
+ mutex_unlock(&buffer->mutex);
return len;
}
+/**
+ * sysfs_get_open_dirent - get or create sysfs_open_dirent
+ * @sd: target sysfs_dirent
+ * @buffer: sysfs_buffer for this instance of open
+ *
+ * If @sd->s_attr.open exists, increment its reference count;
+ * otherwise, create one. @buffer is chained to the buffers
+ * list.
+ *
+ * LOCKING:
+ * Kernel thread context (may sleep).
+ *
+ * RETURNS:
+ * 0 on success, -errno on failure.
+ */
+static int sysfs_get_open_dirent(struct sysfs_dirent *sd,
+ struct sysfs_buffer *buffer)
+{
+ struct sysfs_open_dirent *od, *new_od = NULL;
+
+ retry:
+ spin_lock(&sysfs_open_dirent_lock);
+
+ if (!sd->s_attr.open && new_od) {
+ sd->s_attr.open = new_od;
+ new_od = NULL;
+ }
+
+ od = sd->s_attr.open;
+ if (od) {
+ atomic_inc(&od->refcnt);
+ list_add_tail(&buffer->list, &od->buffers);
+ }
+
+ spin_unlock(&sysfs_open_dirent_lock);
+
+ if (od) {
+ kfree(new_od);
+ return 0;
+ }
+
+ /* not there, initialize a new one and retry */
+ new_od = kmalloc(sizeof(*new_od), GFP_KERNEL);
+ if (!new_od)
+ return -ENOMEM;
+
+ atomic_set(&new_od->refcnt, 0);
+ atomic_set(&new_od->event, 1);
+ init_waitqueue_head(&new_od->poll);
+ INIT_LIST_HEAD(&new_od->buffers);
+ goto retry;
+}
+
+/**
+ * sysfs_put_open_dirent - put sysfs_open_dirent
+ * @sd: target sysfs_dirent
+ * @buffer: associated sysfs_buffer
+ *
+ * Put @sd->s_attr.open and unlink @buffer from the buffers list.
+ * If reference count reaches zero, disassociate and free it.
+ *
+ * LOCKING:
+ * None.
+ */
+static void sysfs_put_open_dirent(struct sysfs_dirent *sd,
+ struct sysfs_buffer *buffer)
+{
+ struct sysfs_open_dirent *od = sd->s_attr.open;
+
+ spin_lock(&sysfs_open_dirent_lock);
+
+ list_del(&buffer->list);
+ if (atomic_dec_and_test(&od->refcnt))
+ sd->s_attr.open = NULL;
+ else
+ od = NULL;
+
+ spin_unlock(&sysfs_open_dirent_lock);
+
+ kfree(od);
+}
+
static int sysfs_open_file(struct inode *inode, struct file *file)
{
struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
- struct kobject *kobj = attr_sd->s_parent->s_elem.dir.kobj;
- struct sysfs_buffer * buffer;
- struct sysfs_ops * ops = NULL;
- int error;
+ struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
+ struct sysfs_buffer *buffer;
+ struct sysfs_ops *ops;
+ int error = -EACCES;
/* need attr_sd for attr and ops, its parent for kobj */
if (!sysfs_get_active_two(attr_sd))
return -ENODEV;
- /* if the kobject has no ktype, then we assume that it is a subsystem
- * itself, and use ops for it.
- */
- if (kobj->kset && kobj->kset->ktype)
- ops = kobj->kset->ktype->sysfs_ops;
- else if (kobj->ktype)
+ /* every kobject with an attribute needs a ktype assigned */
+ if (kobj->ktype && kobj->ktype->sysfs_ops)
ops = kobj->ktype->sysfs_ops;
- else
- ops = &subsys_sysfs_ops;
-
- error = -EACCES;
-
- /* No sysfs operations, either from having no subsystem,
- * or the subsystem have no operations.
- */
- if (!ops)
+ else {
+ printk(KERN_ERR "missing sysfs attribute operations for "
+ "kobject: %s\n", kobject_name(kobj));
+ WARN_ON(1);
goto err_out;
+ }
/* File needs write support.
* The inode's perms must say it's ok,
if (!buffer)
goto err_out;
- init_MUTEX(&buffer->sem);
+ mutex_init(&buffer->mutex);
buffer->needs_read_fill = 1;
buffer->ops = ops;
file->private_data = buffer;
- /* open succeeded, put active references and pin attr_sd */
+ /* make sure we have open dirent struct */
+ error = sysfs_get_open_dirent(attr_sd, buffer);
+ if (error)
+ goto err_free;
+
+ /* open succeeded, put active references */
sysfs_put_active_two(attr_sd);
- sysfs_get(attr_sd);
return 0;
+ err_free:
+ kfree(buffer);
err_out:
sysfs_put_active_two(attr_sd);
return error;
}
-static int sysfs_release(struct inode * inode, struct file * filp)
+static int sysfs_release(struct inode *inode, struct file *filp)
{
- struct sysfs_dirent *attr_sd = filp->f_path.dentry->d_fsdata;
+ struct sysfs_dirent *sd = filp->f_path.dentry->d_fsdata;
struct sysfs_buffer *buffer = filp->private_data;
- sysfs_put(attr_sd);
+ sysfs_put_open_dirent(sd, buffer);
+
+ if (buffer->page)
+ free_page((unsigned long)buffer->page);
+ kfree(buffer);
- if (buffer) {
- if (buffer->page)
- free_page((unsigned long)buffer->page);
- kfree(buffer);
- }
return 0;
}
* again will not get new data, or reset the state of 'poll'.
* Reminder: this only works for attributes which actively support
* it, and it is not possible to test an attribute from userspace
- * to see if it supports poll (Nether 'poll' or 'select' return
+ * to see if it supports poll (Neither 'poll' nor 'select' return
* an appropriate error code). When in doubt, set a suitable timeout value.
*/
static unsigned int sysfs_poll(struct file *filp, poll_table *wait)
{
struct sysfs_buffer * buffer = filp->private_data;
struct sysfs_dirent *attr_sd = filp->f_path.dentry->d_fsdata;
- struct kobject *kobj = attr_sd->s_parent->s_elem.dir.kobj;
+ struct sysfs_open_dirent *od = attr_sd->s_attr.open;
/* need parent for the kobj, grab both */
if (!sysfs_get_active_two(attr_sd))
goto trigger;
- poll_wait(filp, &kobj->poll, wait);
+ poll_wait(filp, &od->poll, wait);
sysfs_put_active_two(attr_sd);
- if (buffer->event != atomic_read(&attr_sd->s_event))
+ if (buffer->event != atomic_read(&od->event))
goto trigger;
return 0;
if (sd && attr)
sd = sysfs_find_dirent(sd, attr);
if (sd) {
- atomic_inc(&sd->s_event);
- wake_up_interruptible(&k->poll);
+ struct sysfs_open_dirent *od;
+
+ spin_lock(&sysfs_open_dirent_lock);
+
+ od = sd->s_attr.open;
+ if (od) {
+ atomic_inc(&od->event);
+ wake_up_interruptible(&od->poll);
+ }
+
+ spin_unlock(&sysfs_open_dirent_lock);
}
mutex_unlock(&sysfs_mutex);
umode_t mode = (attr->mode & S_IALLUGO) | S_IFREG;
struct sysfs_addrm_cxt acxt;
struct sysfs_dirent *sd;
+ int rc;
sd = sysfs_new_dirent(attr->name, mode, type);
if (!sd)
return -ENOMEM;
- sd->s_elem.attr.attr = (void *)attr;
+ sd->s_attr.attr = (void *)attr;
sysfs_addrm_start(&acxt, dir_sd);
+ rc = sysfs_add_one(&acxt, sd);
+ sysfs_addrm_finish(&acxt);
- if (!sysfs_find_dirent(dir_sd, attr->name)) {
- sysfs_add_one(&acxt, sd);
- sysfs_link_sibling(sd);
- }
-
- if (!sysfs_addrm_finish(&acxt)) {
+ if (rc)
sysfs_put(sd);
- return -EEXIST;
- }
- return 0;
+ return rc;
}
/**
* sysfs_create_file - create an attribute file for an object.
* @kobj: object we're creating for.
- * @attr: atrribute descriptor.
+ * @attr: attribute descriptor.
*/
int sysfs_create_file(struct kobject * kobj, const struct attribute * attr)
}
EXPORT_SYMBOL_GPL(sysfs_add_file_to_group);
-
-/**
- * sysfs_update_file - update the modified timestamp on an object attribute.
- * @kobj: object we're acting for.
- * @attr: attribute descriptor.
- */
-int sysfs_update_file(struct kobject * kobj, const struct attribute * attr)
-{
- struct sysfs_dirent *victim_sd = NULL;
- struct dentry *victim = NULL;
- int rc;
-
- rc = -ENOENT;
- victim_sd = sysfs_get_dirent(kobj->sd, attr->name);
- if (!victim_sd)
- goto out;
-
- victim = sysfs_get_dentry(victim_sd);
- if (IS_ERR(victim)) {
- rc = PTR_ERR(victim);
- victim = NULL;
- goto out;
- }
-
- mutex_lock(&victim->d_inode->i_mutex);
- victim->d_inode->i_mtime = CURRENT_TIME;
- fsnotify_modify(victim);
- mutex_unlock(&victim->d_inode->i_mutex);
- rc = 0;
- out:
- dput(victim);
- sysfs_put(victim_sd);
- return rc;
-}
-
-
/**
* sysfs_chmod_file - update the modified mode value on an object attribute.
* @kobj: object we're acting for.
if (!victim_sd)
goto out;
+ mutex_lock(&sysfs_rename_mutex);
victim = sysfs_get_dentry(victim_sd);
+ mutex_unlock(&sysfs_rename_mutex);
if (IS_ERR(victim)) {
rc = PTR_ERR(victim);
victim = NULL;
}
inode = victim->d_inode;
+
mutex_lock(&inode->i_mutex);
+
newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
rc = notify_change(victim, &newattrs);
+
+ if (rc == 0) {
+ mutex_lock(&sysfs_mutex);
+ victim_sd->s_mode = newattrs.ia_mode;
+ mutex_unlock(&sysfs_mutex);
+ }
+
mutex_unlock(&inode->i_mutex);
out:
dput(victim);
EXPORT_SYMBOL_GPL(sysfs_create_file);
EXPORT_SYMBOL_GPL(sysfs_remove_file);
-EXPORT_SYMBOL_GPL(sysfs_update_file);
projects / linux-2.6-omap-h63xx.git / blobdiff