lib/ringbuffer/ring_buffer_vfs.c

   1 /*
   2  * ring_buffer_vfs.c
   3  *
   4  * Ring Buffer VFS file operations.
   5  *
   6  * Copyright (C) 2010-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   7  *
   8  * This library is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; only
  11  * version 2.1 of the License.
  12  *
  13  * This library is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with this library; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 #include <linux/module.h>
  24 #include <linux/fs.h>
  25 #include <linux/compat.h>
  26
  27 #include "../../wrapper/ringbuffer/backend.h"
  28 #include "../../wrapper/ringbuffer/frontend.h"
  29 #include "../../wrapper/ringbuffer/vfs.h"
  30 #include "../../wrapper/poll.h"
  31
  32 static int put_ulong(unsigned long val, unsigned long arg)
  33 {
  34         return put_user(val, (unsigned long __user *)arg);
  35 }
  36
  37 #ifdef CONFIG_COMPAT
  38 static int compat_put_ulong(compat_ulong_t val, unsigned long arg)
  39 {
  40         return put_user(val, (compat_ulong_t __user *)compat_ptr(arg));
  41 }
  42 #endif
  43
  44 int lib_ring_buffer_open(struct inode *inode, struct file *file,
  45                 struct lib_ring_buffer *buf)
  46 {
  47         int ret;
  48
  49         if (!buf)
  50                 return -EINVAL;
  51
  52         ret = lib_ring_buffer_open_read(buf);
  53         if (ret)
  54                 return ret;
  55
  56         ret = nonseekable_open(inode, file);
  57         if (ret)
  58                 goto release_read;
  59         return 0;
  60
  61 release_read:
  62         lib_ring_buffer_release_read(buf);
  63         return ret;
  64 }
  65 EXPORT_SYMBOL_GPL(lib_ring_buffer_open);
  66
  67 /**
  68  *      vfs_lib_ring_buffer_open - ring buffer open file operation
  69  *      @inode: opened inode
  70  *      @file: opened file
  71  *
  72  *      Open implementation. Makes sure only one open instance of a buffer is
  73  *      done at a given moment.
  74  */
  75 static
  76 int vfs_lib_ring_buffer_open(struct inode *inode, struct file *file)
  77 {
  78         struct lib_ring_buffer *buf = inode->i_private;
  79
  80         file->private_data = buf;
  81         return lib_ring_buffer_open(inode, file, buf);
  82 }
  83
  84 int lib_ring_buffer_release(struct inode *inode, struct file *file,
  85                 struct lib_ring_buffer *buf)
  86 {
  87         lib_ring_buffer_release_read(buf);
  88
  89         return 0;
  90 }
  91 EXPORT_SYMBOL_GPL(lib_ring_buffer_release);
  92
  93 /**
  94  *      vfs_lib_ring_buffer_release - ring buffer release file operation
  95  *      @inode: opened inode
  96  *      @file: opened file
  97  *
  98  *      Release implementation.
  99  */
 100 static
 101 int vfs_lib_ring_buffer_release(struct inode *inode, struct file *file)
 102 {
 103         struct lib_ring_buffer *buf = file->private_data;
 104
 105         return lib_ring_buffer_release(inode, file, buf);
 106 }
 107
 108 unsigned int lib_ring_buffer_poll(struct file *filp, poll_table *wait,
 109                 struct lib_ring_buffer *buf)
 110 {
 111         unsigned int mask = 0;
 112         struct channel *chan = buf->backend.chan;
 113         const struct lib_ring_buffer_config *config = &chan->backend.config;
 114         int finalized, disabled;
 115
 116         if (filp->f_mode & FMODE_READ) {
 117                 poll_wait_set_exclusive(wait);
 118                 poll_wait(filp, &buf->read_wait, wait);
 119
 120                 finalized = lib_ring_buffer_is_finalized(config, buf);
 121                 disabled = lib_ring_buffer_channel_is_disabled(chan);
 122
 123                 /*
 124                  * lib_ring_buffer_is_finalized() contains a smp_rmb() ordering
 125                  * finalized load before offsets loads.
 126                  */
 127                 WARN_ON(atomic_long_read(&buf->active_readers) != 1);
 128 retry:
 129                 if (disabled)
 130                         return POLLERR;
 131
 132                 if (subbuf_trunc(lib_ring_buffer_get_offset(config, buf), chan)
 133                   - subbuf_trunc(lib_ring_buffer_get_consumed(config, buf), chan)
 134                   == 0) {
 135                         if (finalized)
 136                                 return POLLHUP;
 137                         else {
 138                                 /*
 139                                  * The memory barriers
 140                                  * __wait_event()/wake_up_interruptible() take
 141                                  * care of "raw_spin_is_locked" memory ordering.
 142                                  */
 143                                 if (raw_spin_is_locked(&buf->raw_tick_nohz_spinlock))
 144                                         goto retry;
 145                                 else
 146                                         return 0;
 147                         }
 148                 } else {
 149                         if (subbuf_trunc(lib_ring_buffer_get_offset(config, buf),
 150                                          chan)
 151                           - subbuf_trunc(lib_ring_buffer_get_consumed(config, buf),
 152                                          chan)
 153                           >= chan->backend.buf_size)
 154                                 return POLLPRI | POLLRDBAND;
 155                         else
 156                                 return POLLIN | POLLRDNORM;
 157                 }
 158         }
 159         return mask;
 160 }
 161 EXPORT_SYMBOL_GPL(lib_ring_buffer_poll);
 162
 163 /**
 164  *      vfs_lib_ring_buffer_poll - ring buffer poll file operation
 165  *      @filp: the file
 166  *      @wait: poll table
 167  *
 168  *      Poll implementation.
 169  */
 170 static
 171 unsigned int vfs_lib_ring_buffer_poll(struct file *filp, poll_table *wait)
 172 {
 173         struct lib_ring_buffer *buf = filp->private_data;
 174
 175         return lib_ring_buffer_poll(filp, wait, buf);
 176 }
 177
 178 long lib_ring_buffer_ioctl(struct file *filp, unsigned int cmd,
 179                 unsigned long arg, struct lib_ring_buffer *buf)
 180 {
 181         struct channel *chan = buf->backend.chan;
 182         const struct lib_ring_buffer_config *config = &chan->backend.config;
 183
 184         if (lib_ring_buffer_channel_is_disabled(chan))
 185                 return -EIO;
 186
 187         switch (cmd) {
 188         case RING_BUFFER_SNAPSHOT:
 189                 return lib_ring_buffer_snapshot(buf, &buf->cons_snapshot,
 190                                             &buf->prod_snapshot);
 191         case RING_BUFFER_SNAPSHOT_GET_CONSUMED:
 192                 return put_ulong(buf->cons_snapshot, arg);
 193         case RING_BUFFER_SNAPSHOT_GET_PRODUCED:
 194                 return put_ulong(buf->prod_snapshot, arg);
 195         case RING_BUFFER_GET_SUBBUF:
 196         {
 197                 unsigned long uconsume;
 198                 long ret;
 199
 200                 ret = get_user(uconsume, (unsigned long __user *) arg);
 201                 if (ret)
 202                         return ret; /* will return -EFAULT */
 203                 ret = lib_ring_buffer_get_subbuf(buf, uconsume);
 204                 if (!ret) {
 205                         /* Set file position to zero at each successful "get" */
 206                         filp->f_pos = 0;
 207                 }
 208                 return ret;
 209         }
 210         case RING_BUFFER_PUT_SUBBUF:
 211                 lib_ring_buffer_put_subbuf(buf);
 212                 return 0;
 213
 214         case RING_BUFFER_GET_NEXT_SUBBUF:
 215         {
 216                 long ret;
 217
 218                 ret = lib_ring_buffer_get_next_subbuf(buf);
 219                 if (!ret) {
 220                         /* Set file position to zero at each successful "get" */
 221                         filp->f_pos = 0;
 222                 }
 223                 return ret;
 224         }
 225         case RING_BUFFER_PUT_NEXT_SUBBUF:
 226                 lib_ring_buffer_put_next_subbuf(buf);
 227                 return 0;
 228         case RING_BUFFER_GET_SUBBUF_SIZE:
 229                 return put_ulong(lib_ring_buffer_get_read_data_size(config, buf),
 230                                  arg);
 231         case RING_BUFFER_GET_PADDED_SUBBUF_SIZE:
 232         {
 233                 unsigned long size;
 234
 235                 size = lib_ring_buffer_get_read_data_size(config, buf);
 236                 size = PAGE_ALIGN(size);
 237                 return put_ulong(size, arg);
 238         }
 239         case RING_BUFFER_GET_MAX_SUBBUF_SIZE:
 240                 return put_ulong(chan->backend.subbuf_size, arg);
 241         case RING_BUFFER_GET_MMAP_LEN:
 242         {
 243                 unsigned long mmap_buf_len;
 244
 245                 if (config->output != RING_BUFFER_MMAP)
 246                         return -EINVAL;
 247                 mmap_buf_len = chan->backend.buf_size;
 248                 if (chan->backend.extra_reader_sb)
 249                         mmap_buf_len += chan->backend.subbuf_size;
 250                 if (mmap_buf_len > INT_MAX)
 251                         return -EFBIG;
 252                 return put_ulong(mmap_buf_len, arg);
 253         }
 254         case RING_BUFFER_GET_MMAP_READ_OFFSET:
 255         {
 256                 unsigned long sb_bindex;
 257
 258                 if (config->output != RING_BUFFER_MMAP)
 259                         return -EINVAL;
 260                 sb_bindex = subbuffer_id_get_index(config,
 261                                                    buf->backend.buf_rsb.id);
 262                 return put_ulong(buf->backend.array[sb_bindex]->mmap_offset,
 263                                  arg);
 264         }
 265         case RING_BUFFER_FLUSH:
 266                 lib_ring_buffer_switch_remote(buf);
 267                 return 0;
 268         default:
 269                 return -ENOIOCTLCMD;
 270         }
 271 }
 272 EXPORT_SYMBOL_GPL(lib_ring_buffer_ioctl);
 273
 274 /**
 275  *      vfs_lib_ring_buffer_ioctl - control ring buffer reader synchronization
 276  *
 277  *      @filp: the file
 278  *      @cmd: the command
 279  *      @arg: command arg
 280  *
 281  *      This ioctl implements commands necessary for producer/consumer
 282  *      and flight recorder reader interaction :
 283  *      RING_BUFFER_GET_NEXT_SUBBUF
 284  *              Get the next sub-buffer that can be read. It never blocks.
 285  *      RING_BUFFER_PUT_NEXT_SUBBUF
 286  *              Release the currently read sub-buffer.
 287  *      RING_BUFFER_GET_SUBBUF_SIZE
 288  *              returns the size of the current sub-buffer.
 289  *      RING_BUFFER_GET_MAX_SUBBUF_SIZE
 290  *              returns the maximum size for sub-buffers.
 291  *      RING_BUFFER_GET_NUM_SUBBUF
 292  *              returns the number of reader-visible sub-buffers in the per cpu
 293  *              channel (for mmap).
 294  *      RING_BUFFER_GET_MMAP_READ_OFFSET
 295  *              returns the offset of the subbuffer belonging to the reader.
 296  *              Should only be used for mmap clients.
 297  */
 298 static
 299 long vfs_lib_ring_buffer_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 300 {
 301         struct lib_ring_buffer *buf = filp->private_data;
 302
 303         return lib_ring_buffer_ioctl(filp, cmd, arg, buf);
 304 }
 305
 306 #ifdef CONFIG_COMPAT
 307 long lib_ring_buffer_compat_ioctl(struct file *filp, unsigned int cmd,
 308                 unsigned long arg, struct lib_ring_buffer *buf)
 309 {
 310         struct channel *chan = buf->backend.chan;
 311         const struct lib_ring_buffer_config *config = &chan->backend.config;
 312
 313         if (lib_ring_buffer_channel_is_disabled(chan))
 314                 return -EIO;
 315
 316         switch (cmd) {
 317         case RING_BUFFER_COMPAT_SNAPSHOT:
 318                 return lib_ring_buffer_snapshot(buf, &buf->cons_snapshot,
 319                                                 &buf->prod_snapshot);
 320         case RING_BUFFER_COMPAT_SNAPSHOT_GET_CONSUMED:
 321                 return compat_put_ulong(buf->cons_snapshot, arg);
 322         case RING_BUFFER_COMPAT_SNAPSHOT_GET_PRODUCED:
 323                 return compat_put_ulong(buf->prod_snapshot, arg);
 324         case RING_BUFFER_COMPAT_GET_SUBBUF:
 325         {
 326                 __u32 uconsume;
 327                 unsigned long consume;
 328                 long ret;
 329
 330                 ret = get_user(uconsume, (__u32 __user *) arg);
 331                 if (ret)
 332                         return ret; /* will return -EFAULT */
 333                 consume = buf->cons_snapshot;
 334                 consume &= ~0xFFFFFFFFL;
 335                 consume |= uconsume;
 336                 ret = lib_ring_buffer_get_subbuf(buf, consume);
 337                 if (!ret) {
 338                         /* Set file position to zero at each successful "get" */
 339                         filp->f_pos = 0;
 340                 }
 341                 return ret;
 342         }
 343         case RING_BUFFER_COMPAT_PUT_SUBBUF:
 344                 lib_ring_buffer_put_subbuf(buf);
 345                 return 0;
 346
 347         case RING_BUFFER_COMPAT_GET_NEXT_SUBBUF:
 348         {
 349                 long ret;
 350
 351                 ret = lib_ring_buffer_get_next_subbuf(buf);
 352                 if (!ret) {
 353                         /* Set file position to zero at each successful "get" */
 354                         filp->f_pos = 0;
 355                 }
 356                 return ret;
 357         }
 358         case RING_BUFFER_COMPAT_PUT_NEXT_SUBBUF:
 359                 lib_ring_buffer_put_next_subbuf(buf);
 360                 return 0;
 361         case RING_BUFFER_COMPAT_GET_SUBBUF_SIZE:
 362         {
 363                 unsigned long data_size;
 364
 365                 data_size = lib_ring_buffer_get_read_data_size(config, buf);
 366                 if (data_size > UINT_MAX)
 367                         return -EFBIG;
 368                 return compat_put_ulong(data_size, arg);
 369         }
 370         case RING_BUFFER_COMPAT_GET_PADDED_SUBBUF_SIZE:
 371         {
 372                 unsigned long size;
 373
 374                 size = lib_ring_buffer_get_read_data_size(config, buf);
 375                 size = PAGE_ALIGN(size);
 376                 if (size > UINT_MAX)
 377                         return -EFBIG;
 378                 return compat_put_ulong(size, arg);
 379         }
 380         case RING_BUFFER_COMPAT_GET_MAX_SUBBUF_SIZE:
 381                 if (chan->backend.subbuf_size > UINT_MAX)
 382                         return -EFBIG;
 383                 return compat_put_ulong(chan->backend.subbuf_size, arg);
 384         case RING_BUFFER_COMPAT_GET_MMAP_LEN:
 385         {
 386                 unsigned long mmap_buf_len;
 387
 388                 if (config->output != RING_BUFFER_MMAP)
 389                         return -EINVAL;
 390                 mmap_buf_len = chan->backend.buf_size;
 391                 if (chan->backend.extra_reader_sb)
 392                         mmap_buf_len += chan->backend.subbuf_size;
 393                 if (mmap_buf_len > UINT_MAX)
 394                         return -EFBIG;
 395                 return compat_put_ulong(mmap_buf_len, arg);
 396         }
 397         case RING_BUFFER_COMPAT_GET_MMAP_READ_OFFSET:
 398         {
 399                 unsigned long sb_bindex, read_offset;
 400
 401                 if (config->output != RING_BUFFER_MMAP)
 402                         return -EINVAL;
 403                 sb_bindex = subbuffer_id_get_index(config,
 404                                                    buf->backend.buf_rsb.id);
 405                 read_offset = buf->backend.array[sb_bindex]->mmap_offset;
 406                 if (read_offset > UINT_MAX)
 407                         return -EINVAL;
 408                 return compat_put_ulong(read_offset, arg);
 409         }
 410         case RING_BUFFER_COMPAT_FLUSH:
 411                 lib_ring_buffer_switch_remote(buf);
 412                 return 0;
 413         default:
 414                 return -ENOIOCTLCMD;
 415         }
 416 }
 417 EXPORT_SYMBOL_GPL(lib_ring_buffer_compat_ioctl);
 418
 419 static
 420 long vfs_lib_ring_buffer_compat_ioctl(struct file *filp, unsigned int cmd,
 421                                   unsigned long arg)
 422 {
 423         struct lib_ring_buffer *buf = filp->private_data;
 424
 425         return lib_ring_buffer_compat_ioctl(filp, cmd, arg, buf);
 426 }
 427 #endif
 428
 429 const struct file_operations lib_ring_buffer_file_operations = {
 430         .owner = THIS_MODULE,
 431         .open = vfs_lib_ring_buffer_open,
 432         .release = vfs_lib_ring_buffer_release,
 433         .poll = vfs_lib_ring_buffer_poll,
 434         .splice_read = vfs_lib_ring_buffer_splice_read,
 435         .mmap = vfs_lib_ring_buffer_mmap,
 436         .unlocked_ioctl = vfs_lib_ring_buffer_ioctl,
 437         .llseek = vfs_lib_ring_buffer_no_llseek,
 438 #ifdef CONFIG_COMPAT
 439         .compat_ioctl = vfs_lib_ring_buffer_compat_ioctl,
 440 #endif
 441 };
 442 EXPORT_SYMBOL_GPL(lib_ring_buffer_file_operations);
 443
 444 MODULE_LICENSE("GPL and additional rights");
 445 MODULE_AUTHOR("Mathieu Desnoyers");
 446 MODULE_DESCRIPTION("Ring Buffer Library VFS");