linux/fs/sysfs/bin.c
Eric W. Biederman e72ceb8cca sysfs: Remove sysfs_get/put_active_two
It turns out that holding an active reference on a directory is
pointless.  The purpose of the active references are to allows us to
block when removing sysfs entries that have custom methods so we don't
remove modules while running modular code and to keep those custom
methods from accessing data structures after the files have been
removed.  Further sysfs_remove_dir remove all elements in the
directory before removing the directory itself, so there is no chance
we will remove a directory with active children.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2010-03-07 17:04:51 -08:00

509 lines
11 KiB
C

/*
* fs/sysfs/bin.c - sysfs binary file implementation
*
* Copyright (c) 2003 Patrick Mochel
* Copyright (c) 2003 Matthew Wilcox
* Copyright (c) 2004 Silicon Graphics, Inc.
* 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.
*/
#undef DEBUG
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/kobject.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/mutex.h>
#include <linux/mm.h>
#include <asm/uaccess.h>
#include "sysfs.h"
/*
* There's one bin_buffer for each open file.
*
* filp->private_data points to bin_buffer and
* sysfs_dirent->s_bin_attr.buffers points to a the bin_buffer s
* sysfs_dirent->s_bin_attr.buffers is protected by sysfs_bin_lock
*/
static DEFINE_MUTEX(sysfs_bin_lock);
struct bin_buffer {
struct mutex mutex;
void *buffer;
int mmapped;
const struct vm_operations_struct *vm_ops;
struct file *file;
struct hlist_node list;
};
static int
fill_read(struct dentry *dentry, char *buffer, loff_t off, size_t count)
{
struct sysfs_dirent *attr_sd = dentry->d_fsdata;
struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
int rc;
/* need attr_sd for attr, its parent for kobj */
if (!sysfs_get_active(attr_sd))
return -ENODEV;
rc = -EIO;
if (attr->read)
rc = attr->read(kobj, attr, buffer, off, count);
sysfs_put_active(attr_sd);
return rc;
}
static ssize_t
read(struct file *file, char __user *userbuf, size_t bytes, loff_t *off)
{
struct bin_buffer *bb = file->private_data;
struct dentry *dentry = file->f_path.dentry;
int size = dentry->d_inode->i_size;
loff_t offs = *off;
int count = min_t(size_t, bytes, PAGE_SIZE);
char *temp;
if (!bytes)
return 0;
if (size) {
if (offs > size)
return 0;
if (offs + count > size)
count = size - offs;
}
temp = kmalloc(count, GFP_KERNEL);
if (!temp)
return -ENOMEM;
mutex_lock(&bb->mutex);
count = fill_read(dentry, bb->buffer, offs, count);
if (count < 0) {
mutex_unlock(&bb->mutex);
goto out_free;
}
memcpy(temp, bb->buffer, count);
mutex_unlock(&bb->mutex);
if (copy_to_user(userbuf, temp, count)) {
count = -EFAULT;
goto out_free;
}
pr_debug("offs = %lld, *off = %lld, count = %d\n", offs, *off, count);
*off = offs + count;
out_free:
kfree(temp);
return count;
}
static int
flush_write(struct dentry *dentry, char *buffer, loff_t offset, size_t count)
{
struct sysfs_dirent *attr_sd = dentry->d_fsdata;
struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
int rc;
/* need attr_sd for attr, its parent for kobj */
if (!sysfs_get_active(attr_sd))
return -ENODEV;
rc = -EIO;
if (attr->write)
rc = attr->write(kobj, attr, buffer, offset, count);
sysfs_put_active(attr_sd);
return rc;
}
static ssize_t write(struct file *file, const char __user *userbuf,
size_t bytes, loff_t *off)
{
struct bin_buffer *bb = file->private_data;
struct dentry *dentry = file->f_path.dentry;
int size = dentry->d_inode->i_size;
loff_t offs = *off;
int count = min_t(size_t, bytes, PAGE_SIZE);
char *temp;
if (!bytes)
return 0;
if (size) {
if (offs > size)
return 0;
if (offs + count > size)
count = size - offs;
}
temp = memdup_user(userbuf, count);
if (IS_ERR(temp))
return PTR_ERR(temp);
mutex_lock(&bb->mutex);
memcpy(bb->buffer, temp, count);
count = flush_write(dentry, bb->buffer, offs, count);
mutex_unlock(&bb->mutex);
if (count > 0)
*off = offs + count;
kfree(temp);
return count;
}
static void bin_vma_open(struct vm_area_struct *vma)
{
struct file *file = vma->vm_file;
struct bin_buffer *bb = file->private_data;
struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
if (!bb->vm_ops || !bb->vm_ops->open)
return;
if (!sysfs_get_active(attr_sd))
return;
bb->vm_ops->open(vma);
sysfs_put_active(attr_sd);
}
static void bin_vma_close(struct vm_area_struct *vma)
{
struct file *file = vma->vm_file;
struct bin_buffer *bb = file->private_data;
struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
if (!bb->vm_ops || !bb->vm_ops->close)
return;
if (!sysfs_get_active(attr_sd))
return;
bb->vm_ops->close(vma);
sysfs_put_active(attr_sd);
}
static int bin_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
struct file *file = vma->vm_file;
struct bin_buffer *bb = file->private_data;
struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
int ret;
if (!bb->vm_ops || !bb->vm_ops->fault)
return VM_FAULT_SIGBUS;
if (!sysfs_get_active(attr_sd))
return VM_FAULT_SIGBUS;
ret = bb->vm_ops->fault(vma, vmf);
sysfs_put_active(attr_sd);
return ret;
}
static int bin_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
{
struct file *file = vma->vm_file;
struct bin_buffer *bb = file->private_data;
struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
int ret;
if (!bb->vm_ops)
return VM_FAULT_SIGBUS;
if (!bb->vm_ops->page_mkwrite)
return 0;
if (!sysfs_get_active(attr_sd))
return VM_FAULT_SIGBUS;
ret = bb->vm_ops->page_mkwrite(vma, vmf);
sysfs_put_active(attr_sd);
return ret;
}
static int bin_access(struct vm_area_struct *vma, unsigned long addr,
void *buf, int len, int write)
{
struct file *file = vma->vm_file;
struct bin_buffer *bb = file->private_data;
struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
int ret;
if (!bb->vm_ops || !bb->vm_ops->access)
return -EINVAL;
if (!sysfs_get_active(attr_sd))
return -EINVAL;
ret = bb->vm_ops->access(vma, addr, buf, len, write);
sysfs_put_active(attr_sd);
return ret;
}
#ifdef CONFIG_NUMA
static int bin_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
{
struct file *file = vma->vm_file;
struct bin_buffer *bb = file->private_data;
struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
int ret;
if (!bb->vm_ops || !bb->vm_ops->set_policy)
return 0;
if (!sysfs_get_active(attr_sd))
return -EINVAL;
ret = bb->vm_ops->set_policy(vma, new);
sysfs_put_active(attr_sd);
return ret;
}
static struct mempolicy *bin_get_policy(struct vm_area_struct *vma,
unsigned long addr)
{
struct file *file = vma->vm_file;
struct bin_buffer *bb = file->private_data;
struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
struct mempolicy *pol;
if (!bb->vm_ops || !bb->vm_ops->get_policy)
return vma->vm_policy;
if (!sysfs_get_active(attr_sd))
return vma->vm_policy;
pol = bb->vm_ops->get_policy(vma, addr);
sysfs_put_active(attr_sd);
return pol;
}
static int bin_migrate(struct vm_area_struct *vma, const nodemask_t *from,
const nodemask_t *to, unsigned long flags)
{
struct file *file = vma->vm_file;
struct bin_buffer *bb = file->private_data;
struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
int ret;
if (!bb->vm_ops || !bb->vm_ops->migrate)
return 0;
if (!sysfs_get_active(attr_sd))
return 0;
ret = bb->vm_ops->migrate(vma, from, to, flags);
sysfs_put_active(attr_sd);
return ret;
}
#endif
static const struct vm_operations_struct bin_vm_ops = {
.open = bin_vma_open,
.close = bin_vma_close,
.fault = bin_fault,
.page_mkwrite = bin_page_mkwrite,
.access = bin_access,
#ifdef CONFIG_NUMA
.set_policy = bin_set_policy,
.get_policy = bin_get_policy,
.migrate = bin_migrate,
#endif
};
static int mmap(struct file *file, struct vm_area_struct *vma)
{
struct bin_buffer *bb = file->private_data;
struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
int rc;
mutex_lock(&bb->mutex);
/* need attr_sd for attr, its parent for kobj */
rc = -ENODEV;
if (!sysfs_get_active(attr_sd))
goto out_unlock;
rc = -EINVAL;
if (!attr->mmap)
goto out_put;
rc = attr->mmap(kobj, attr, vma);
if (rc)
goto out_put;
/*
* PowerPC's pci_mmap of legacy_mem uses shmem_zero_setup()
* to satisfy versions of X which crash if the mmap fails: that
* substitutes a new vm_file, and we don't then want bin_vm_ops.
*/
if (vma->vm_file != file)
goto out_put;
rc = -EINVAL;
if (bb->mmapped && bb->vm_ops != vma->vm_ops)
goto out_put;
rc = 0;
bb->mmapped = 1;
bb->vm_ops = vma->vm_ops;
vma->vm_ops = &bin_vm_ops;
out_put:
sysfs_put_active(attr_sd);
out_unlock:
mutex_unlock(&bb->mutex);
return rc;
}
static int open(struct inode * inode, struct file * file)
{
struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
struct bin_buffer *bb = NULL;
int error;
/* binary file operations requires both @sd and its parent */
if (!sysfs_get_active(attr_sd))
return -ENODEV;
error = -EACCES;
if ((file->f_mode & FMODE_WRITE) && !(attr->write || attr->mmap))
goto err_out;
if ((file->f_mode & FMODE_READ) && !(attr->read || attr->mmap))
goto err_out;
error = -ENOMEM;
bb = kzalloc(sizeof(*bb), GFP_KERNEL);
if (!bb)
goto err_out;
bb->buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
if (!bb->buffer)
goto err_out;
mutex_init(&bb->mutex);
bb->file = file;
file->private_data = bb;
mutex_lock(&sysfs_bin_lock);
hlist_add_head(&bb->list, &attr_sd->s_bin_attr.buffers);
mutex_unlock(&sysfs_bin_lock);
/* open succeeded, put active references */
sysfs_put_active(attr_sd);
return 0;
err_out:
sysfs_put_active(attr_sd);
kfree(bb);
return error;
}
static int release(struct inode * inode, struct file * file)
{
struct bin_buffer *bb = file->private_data;
mutex_lock(&sysfs_bin_lock);
hlist_del(&bb->list);
mutex_unlock(&sysfs_bin_lock);
kfree(bb->buffer);
kfree(bb);
return 0;
}
const struct file_operations bin_fops = {
.read = read,
.write = write,
.mmap = mmap,
.llseek = generic_file_llseek,
.open = open,
.release = release,
};
void unmap_bin_file(struct sysfs_dirent *attr_sd)
{
struct bin_buffer *bb;
struct hlist_node *tmp;
if (sysfs_type(attr_sd) != SYSFS_KOBJ_BIN_ATTR)
return;
mutex_lock(&sysfs_bin_lock);
hlist_for_each_entry(bb, tmp, &attr_sd->s_bin_attr.buffers, list) {
struct inode *inode = bb->file->f_path.dentry->d_inode;
unmap_mapping_range(inode->i_mapping, 0, 0, 1);
}
mutex_unlock(&sysfs_bin_lock);
}
/**
* 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, SYSFS_KOBJ_BIN_ATTR);
}
/**
* 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)
{
sysfs_hash_and_remove(kobj->sd, attr->attr.name);
}
EXPORT_SYMBOL_GPL(sysfs_create_bin_file);
EXPORT_SYMBOL_GPL(sysfs_remove_bin_file);