fs/sysfs/bin.c

   1 /*
   2  * fs/sysfs/bin.c - sysfs binary file implementation
   3  *
   4  * Copyright (c) 2003 Patrick Mochel
   5  * Copyright (c) 2003 Matthew Wilcox
   6  * Copyright (c) 2004 Silicon Graphics, Inc.
   7  * Copyright (c) 2007 SUSE Linux Products GmbH
   8  * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
   9  *
  10  * This file is released under the GPLv2.
  11  *
  12  * Please see Documentation/filesystems/sysfs.txt for more information.
  13  */
  14
  15 #undef DEBUG
  16
  17 #include <linux/errno.h>
  18 #include <linux/fs.h>
  19 #include <linux/kernel.h>
  20 #include <linux/kobject.h>
  21 #include <linux/module.h>
  22 #include <linux/slab.h>
  23 #include <linux/mutex.h>
  24
  25 #include <asm/uaccess.h>
  26
  27 #include "sysfs.h"
  28
  29 struct bin_buffer {
  30         struct mutex    mutex;
  31         void            *buffer;
  32         int             mmapped;
  33 };
  34
  35 static int
  36 fill_read(struct dentry *dentry, char *buffer, loff_t off, size_t count)
  37 {
  38         struct sysfs_dirent *attr_sd = dentry->d_fsdata;
  39         struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
  40         struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
  41         int rc;
  42
  43         /* need attr_sd for attr, its parent for kobj */
  44         if (!sysfs_get_active_two(attr_sd))
  45                 return -ENODEV;
  46
  47         rc = -EIO;
  48         if (attr->read)
  49                 rc = attr->read(kobj, attr, buffer, off, count);
  50
  51         sysfs_put_active_two(attr_sd);
  52
  53         return rc;
  54 }
  55
  56 static ssize_t
  57 read(struct file *file, char __user *userbuf, size_t bytes, loff_t *off)
  58 {
  59         struct bin_buffer *bb = file->private_data;
  60         struct dentry *dentry = file->f_path.dentry;
  61         int size = dentry->d_inode->i_size;
  62         loff_t offs = *off;
  63         int count = min_t(size_t, bytes, PAGE_SIZE);
  64         char *temp;
  65
  66         if (size) {
  67                 if (offs > size)
  68                         return 0;
  69                 if (offs + count > size)
  70                         count = size - offs;
  71         }
  72
  73         temp = kmalloc(count, GFP_KERNEL);
  74         if (!temp)
  75                 return -ENOMEM;
  76
  77         mutex_lock(&bb->mutex);
  78
  79         count = fill_read(dentry, bb->buffer, offs, count);
  80         if (count < 0) {
  81                 mutex_unlock(&bb->mutex);
  82                 goto out_free;
  83         }
  84
  85         memcpy(temp, bb->buffer, count);
  86
  87         mutex_unlock(&bb->mutex);
  88
  89         if (copy_to_user(userbuf, temp, count)) {
  90                 count = -EFAULT;
  91                 goto out_free;
  92         }
  93
  94         pr_debug("offs = %lld, *off = %lld, count = %d\n", offs, *off, count);
  95
  96         *off = offs + count;
  97
  98  out_free:
  99         kfree(temp);
 100         return count;
 101 }
 102
 103 static int
 104 flush_write(struct dentry *dentry, char *buffer, loff_t offset, size_t count)
 105 {
 106         struct sysfs_dirent *attr_sd = dentry->d_fsdata;
 107         struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
 108         struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
 109         int rc;
 110
 111         /* need attr_sd for attr, its parent for kobj */
 112         if (!sysfs_get_active_two(attr_sd))
 113                 return -ENODEV;
 114
 115         rc = -EIO;
 116         if (attr->write)
 117                 rc = attr->write(kobj, attr, buffer, offset, count);
 118
 119         sysfs_put_active_two(attr_sd);
 120
 121         return rc;
 122 }
 123
 124 static ssize_t write(struct file *file, const char __user *userbuf,
 125                      size_t bytes, loff_t *off)
 126 {
 127         struct bin_buffer *bb = file->private_data;
 128         struct dentry *dentry = file->f_path.dentry;
 129         int size = dentry->d_inode->i_size;
 130         loff_t offs = *off;
 131         int count = min_t(size_t, bytes, PAGE_SIZE);
 132         char *temp;
 133
 134         if (size) {
 135                 if (offs > size)
 136                         return 0;
 137                 if (offs + count > size)
 138                         count = size - offs;
 139         }
 140
 141         temp = kmalloc(count, GFP_KERNEL);
 142         if (!temp)
 143                 return -ENOMEM;
 144
 145         if (copy_from_user(temp, userbuf, count)) {
 146                 count = -EFAULT;
 147                 goto out_free;
 148         }
 149
 150         mutex_lock(&bb->mutex);
 151
 152         memcpy(bb->buffer, temp, count);
 153
 154         count = flush_write(dentry, bb->buffer, offs, count);
 155         mutex_unlock(&bb->mutex);
 156
 157         if (count > 0)
 158                 *off = offs + count;
 159
 160 out_free:
 161         kfree(temp);
 162         return count;
 163 }
 164
 165 static int mmap(struct file *file, struct vm_area_struct *vma)
 166 {
 167         struct bin_buffer *bb = file->private_data;
 168         struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
 169         struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
 170         struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
 171         int rc;
 172
 173         mutex_lock(&bb->mutex);
 174
 175         /* need attr_sd for attr, its parent for kobj */
 176         if (!sysfs_get_active_two(attr_sd))
 177                 return -ENODEV;
 178
 179         rc = -EINVAL;
 180         if (attr->mmap)
 181                 rc = attr->mmap(kobj, attr, vma);
 182
 183         if (rc == 0 && !bb->mmapped)
 184                 bb->mmapped = 1;
 185         else
 186                 sysfs_put_active_two(attr_sd);
 187
 188         mutex_unlock(&bb->mutex);
 189
 190         return rc;
 191 }
 192
 193 static int open(struct inode * inode, struct file * file)
 194 {
 195         struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
 196         struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
 197         struct bin_buffer *bb = NULL;
 198         int error;
 199
 200         /* binary file operations requires both @sd and its parent */
 201         if (!sysfs_get_active_two(attr_sd))
 202                 return -ENODEV;
 203
 204         error = -EACCES;
 205         if ((file->f_mode & FMODE_WRITE) && !(attr->write || attr->mmap))
 206                 goto err_out;
 207         if ((file->f_mode & FMODE_READ) && !(attr->read || attr->mmap))
 208                 goto err_out;
 209
 210         error = -ENOMEM;
 211         bb = kzalloc(sizeof(*bb), GFP_KERNEL);
 212         if (!bb)
 213                 goto err_out;
 214
 215         bb->buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
 216         if (!bb->buffer)
 217                 goto err_out;
 218
 219         mutex_init(&bb->mutex);
 220         file->private_data = bb;
 221
 222         /* open succeeded, put active references */
 223         sysfs_put_active_two(attr_sd);
 224         return 0;
 225
 226  err_out:
 227         sysfs_put_active_two(attr_sd);
 228         kfree(bb);
 229         return error;
 230 }
 231
 232 static int release(struct inode * inode, struct file * file)
 233 {
 234         struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
 235         struct bin_buffer *bb = file->private_data;
 236
 237         if (bb->mmapped)
 238                 sysfs_put_active_two(attr_sd);
 239         kfree(bb->buffer);
 240         kfree(bb);
 241         return 0;
 242 }
 243
 244 const struct file_operations bin_fops = {
 245         .read           = read,
 246         .write          = write,
 247         .mmap           = mmap,
 248         .llseek         = generic_file_llseek,
 249         .open           = open,
 250         .release        = release,
 251 };
 252
 253 /**
 254  *      sysfs_create_bin_file - create binary file for object.
 255  *      @kobj:  object.
 256  *      @attr:  attribute descriptor.
 257  */
 258
 259 int sysfs_create_bin_file(struct kobject * kobj, struct bin_attribute * attr)
 260 {
 261         BUG_ON(!kobj || !kobj->sd || !attr);
 262
 263         return sysfs_add_file(kobj->sd, &attr->attr, SYSFS_KOBJ_BIN_ATTR);
 264 }
 265
 266
 267 /**
 268  *      sysfs_remove_bin_file - remove binary file for object.
 269  *      @kobj:  object.
 270  *      @attr:  attribute descriptor.
 271  */
 272
 273 void sysfs_remove_bin_file(struct kobject * kobj, struct bin_attribute * attr)
 274 {
 275         sysfs_hash_and_remove(kobj->sd, attr->attr.name);
 276 }
 277
 278 EXPORT_SYMBOL_GPL(sysfs_create_bin_file);
 279 EXPORT_SYMBOL_GPL(sysfs_remove_bin_file);