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 #include <lttng-tracer.h>
  32
  33 static int put_ulong(unsigned long val, unsigned long arg)
  34 {
  35         return put_user(val, (unsigned long __user *)arg);
  36 }
  37
  38 #ifdef CONFIG_COMPAT
  39 static int compat_put_ulong(compat_ulong_t val, unsigned long arg)
  40 {
  41         return put_user(val, (compat_ulong_t __user *)compat_ptr(arg));
  42 }
  43 #endif
  44
  45 /*
  46  * This is not used by anonymous file descriptors. This code is left
  47  * there if we ever want to implement an inode with open() operation.
  48  */
  49 int lib_ring_buffer_open(struct inode *inode, struct file *file,
  50                 struct lib_ring_buffer *buf)
  51 {
  52         int ret;
  53
  54         if (!buf)
  55                 return -EINVAL;
  56
  57         ret = lib_ring_buffer_open_read(buf);
  58         if (ret)
  59                 return ret;
  60
  61         ret = nonseekable_open(inode, file);
  62         if (ret)
  63                 goto release_read;
  64         return 0;
  65
  66 release_read:
  67         lib_ring_buffer_release_read(buf);
  68         return ret;
  69 }
  70 EXPORT_SYMBOL_GPL(lib_ring_buffer_open);
  71
  72 /**
  73  *      vfs_lib_ring_buffer_open - ring buffer open file operation
  74  *      @inode: opened inode
  75  *      @file: opened file
  76  *
  77  *      Open implementation. Makes sure only one open instance of a buffer is
  78  *      done at a given moment.
  79  */
  80 static
  81 int vfs_lib_ring_buffer_open(struct inode *inode, struct file *file)
  82 {
  83         struct lib_ring_buffer *buf = inode->i_private;
  84
  85         file->private_data = buf;
  86         return lib_ring_buffer_open(inode, file, buf);
  87 }
  88
  89 int lib_ring_buffer_release(struct inode *inode, struct file *file,
  90                 struct lib_ring_buffer *buf)
  91 {
  92         lib_ring_buffer_release_read(buf);
  93
  94         return 0;
  95 }
  96 EXPORT_SYMBOL_GPL(lib_ring_buffer_release);
  97
  98 /**
  99  *      vfs_lib_ring_buffer_release - ring buffer release file operation
 100  *      @inode: opened inode
 101  *      @file: opened file
 102  *
 103  *      Release implementation.
 104  */
 105 static
 106 int vfs_lib_ring_buffer_release(struct inode *inode, struct file *file)
 107 {
 108         struct lib_ring_buffer *buf = file->private_data;
 109
 110         return lib_ring_buffer_release(inode, file, buf);
 111 }
 112
 113 unsigned int lib_ring_buffer_poll(struct file *filp, poll_table *wait,
 114                 struct lib_ring_buffer *buf)
 115 {
 116         unsigned int mask = 0;
 117         struct channel *chan = buf->backend.chan;
 118         const struct lib_ring_buffer_config *config = &chan->backend.config;
 119         int finalized, disabled;
 120
 121         if (filp->f_mode & FMODE_READ) {
 122                 poll_wait_set_exclusive(wait);
 123                 poll_wait(filp, &buf->read_wait, wait);
 124
 125                 finalized = lib_ring_buffer_is_finalized(config, buf);
 126                 disabled = lib_ring_buffer_channel_is_disabled(chan);
 127
 128                 /*
 129                  * lib_ring_buffer_is_finalized() contains a smp_rmb() ordering
 130                  * finalized load before offsets loads.
 131                  */
 132                 WARN_ON(atomic_long_read(&buf->active_readers) != 1);
 133 retry:
 134                 if (disabled)
 135                         return POLLERR;
 136
 137                 if (subbuf_trunc(lib_ring_buffer_get_offset(config, buf), chan)
 138                   - subbuf_trunc(lib_ring_buffer_get_consumed(config, buf), chan)
 139                   == 0) {
 140                         if (finalized)
 141                                 return POLLHUP;
 142                         else {
 143                                 /*
 144                                  * The memory barriers
 145                                  * __wait_event()/wake_up_interruptible() take
 146                                  * care of "raw_spin_is_locked" memory ordering.
 147                                  */
 148                                 if (raw_spin_is_locked(&buf->raw_tick_nohz_spinlock))
 149                                         goto retry;
 150                                 else
 151                                         return 0;
 152                         }
 153                 } else {
 154                         if (subbuf_trunc(lib_ring_buffer_get_offset(config, buf),
 155                                          chan)
 156                           - subbuf_trunc(lib_ring_buffer_get_consumed(config, buf),
 157                                          chan)
 158                           >= chan->backend.buf_size)
 159                                 return POLLPRI | POLLRDBAND;
 160                         else
 161                                 return POLLIN | POLLRDNORM;
 162                 }
 163         }
 164         return mask;
 165 }
 166 EXPORT_SYMBOL_GPL(lib_ring_buffer_poll);
 167
 168 /**
 169  *      vfs_lib_ring_buffer_poll - ring buffer poll file operation
 170  *      @filp: the file
 171  *      @wait: poll table
 172  *
 173  *      Poll implementation.
 174  */
 175 static
 176 unsigned int vfs_lib_ring_buffer_poll(struct file *filp, poll_table *wait)
 177 {
 178         struct lib_ring_buffer *buf = filp->private_data;
 179
 180         return lib_ring_buffer_poll(filp, wait, buf);
 181 }
 182
 183 long lib_ring_buffer_ioctl(struct file *filp, unsigned int cmd,
 184                 unsigned long arg, struct lib_ring_buffer *buf)
 185 {
 186         struct channel *chan = buf->backend.chan;
 187         const struct lib_ring_buffer_config *config = &chan->backend.config;
 188
 189         if (lib_ring_buffer_channel_is_disabled(chan))
 190                 return -EIO;
 191
 192         switch (cmd) {
 193         case RING_BUFFER_SNAPSHOT:
 194                 /*
 195                  * First, ensure we perform a "final" flush onto the
 196                  * stream.  This will ensure we create a packet of
 197                  * padding if we encounter an empty packet. This ensures
 198                  * the time-stamps right before the snapshot is used as
 199                  * end of packet timestamp.
 200                  */
 201                 if (!buf->quiescent)
 202                         lib_ring_buffer_switch_remote_empty(buf);
 203                 return lib_ring_buffer_snapshot(buf, &buf->cons_snapshot,
 204                                             &buf->prod_snapshot);
 205         case RING_BUFFER_SNAPSHOT_GET_CONSUMED:
 206                 return put_ulong(buf->cons_snapshot, arg);
 207         case RING_BUFFER_SNAPSHOT_GET_PRODUCED:
 208                 return put_ulong(buf->prod_snapshot, arg);
 209         case RING_BUFFER_GET_SUBBUF:
 210         {
 211                 unsigned long uconsume;
 212                 long ret;
 213
 214                 ret = get_user(uconsume, (unsigned long __user *) arg);
 215                 if (ret)
 216                         return ret; /* will return -EFAULT */
 217                 ret = lib_ring_buffer_get_subbuf(buf, uconsume);
 218                 if (!ret) {
 219                         /* Set file position to zero at each successful "get" */
 220                         filp->f_pos = 0;
 221                 }
 222                 return ret;
 223         }
 224         case RING_BUFFER_PUT_SUBBUF:
 225                 lib_ring_buffer_put_subbuf(buf);
 226                 return 0;
 227
 228         case RING_BUFFER_GET_NEXT_SUBBUF:
 229         {
 230                 long ret;
 231
 232                 ret = lib_ring_buffer_get_next_subbuf(buf);
 233                 if (!ret) {
 234                         /* Set file position to zero at each successful "get" */
 235                         filp->f_pos = 0;
 236                 }
 237                 return ret;
 238         }
 239         case RING_BUFFER_PUT_NEXT_SUBBUF:
 240                 lib_ring_buffer_put_next_subbuf(buf);
 241                 return 0;
 242         case RING_BUFFER_GET_SUBBUF_SIZE:
 243                 return put_ulong(lib_ring_buffer_get_read_data_size(config, buf),
 244                                  arg);
 245         case RING_BUFFER_GET_PADDED_SUBBUF_SIZE:
 246         {
 247                 unsigned long size;
 248
 249                 size = lib_ring_buffer_get_read_data_size(config, buf);
 250                 size = PAGE_ALIGN(size);
 251                 return put_ulong(size, arg);
 252         }
 253         case RING_BUFFER_GET_MAX_SUBBUF_SIZE:
 254                 return put_ulong(chan->backend.subbuf_size, arg);
 255         case RING_BUFFER_GET_MMAP_LEN:
 256         {
 257                 unsigned long mmap_buf_len;
 258
 259                 if (config->output != RING_BUFFER_MMAP)
 260                         return -EINVAL;
 261                 mmap_buf_len = chan->backend.buf_size;
 262                 if (chan->backend.extra_reader_sb)
 263                         mmap_buf_len += chan->backend.subbuf_size;
 264                 if (mmap_buf_len > INT_MAX)
 265                         return -EFBIG;
 266                 return put_ulong(mmap_buf_len, arg);
 267         }
 268         case RING_BUFFER_GET_MMAP_READ_OFFSET:
 269         {
 270                 unsigned long sb_bindex;
 271
 272                 if (config->output != RING_BUFFER_MMAP)
 273                         return -EINVAL;
 274                 sb_bindex = subbuffer_id_get_index(config,
 275                                                    buf->backend.buf_rsb.id);
 276                 return put_ulong(buf->backend.array[sb_bindex]->mmap_offset,
 277                                  arg);
 278         }
 279         case RING_BUFFER_FLUSH:
 280                 lib_ring_buffer_switch_remote(buf);
 281                 return 0;
 282         default:
 283                 return -ENOIOCTLCMD;
 284         }
 285 }
 286 EXPORT_SYMBOL_GPL(lib_ring_buffer_ioctl);
 287
 288 /**
 289  *      vfs_lib_ring_buffer_ioctl - control ring buffer reader synchronization
 290  *
 291  *      @filp: the file
 292  *      @cmd: the command
 293  *      @arg: command arg
 294  *
 295  *      This ioctl implements commands necessary for producer/consumer
 296  *      and flight recorder reader interaction :
 297  *      RING_BUFFER_GET_NEXT_SUBBUF
 298  *              Get the next sub-buffer that can be read. It never blocks.
 299  *      RING_BUFFER_PUT_NEXT_SUBBUF
 300  *              Release the currently read sub-buffer.
 301  *      RING_BUFFER_GET_SUBBUF_SIZE
 302  *              returns the size of the current sub-buffer.
 303  *      RING_BUFFER_GET_MAX_SUBBUF_SIZE
 304  *              returns the maximum size for sub-buffers.
 305  *      RING_BUFFER_GET_NUM_SUBBUF
 306  *              returns the number of reader-visible sub-buffers in the per cpu
 307  *              channel (for mmap).
 308  *      RING_BUFFER_GET_MMAP_READ_OFFSET
 309  *              returns the offset of the subbuffer belonging to the reader.
 310  *              Should only be used for mmap clients.
 311  */
 312 static
 313 long vfs_lib_ring_buffer_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 314 {
 315         struct lib_ring_buffer *buf = filp->private_data;
 316
 317         return lib_ring_buffer_ioctl(filp, cmd, arg, buf);
 318 }
 319
 320 #ifdef CONFIG_COMPAT
 321 long lib_ring_buffer_compat_ioctl(struct file *filp, unsigned int cmd,
 322                 unsigned long arg, struct lib_ring_buffer *buf)
 323 {
 324         struct channel *chan = buf->backend.chan;
 325         const struct lib_ring_buffer_config *config = &chan->backend.config;
 326
 327         if (lib_ring_buffer_channel_is_disabled(chan))
 328                 return -EIO;
 329
 330         switch (cmd) {
 331         case RING_BUFFER_COMPAT_SNAPSHOT:
 332                 /*
 333                  * First, ensure we perform a "final" flush onto the
 334                  * stream.  This will ensure we create a packet of
 335                  * padding if we encounter an empty packet. This ensures
 336                  * the time-stamps right before the snapshot is used as
 337                  * end of packet timestamp.
 338                  */
 339                 if (!buf->quiescent)
 340                         lib_ring_buffer_switch_remote_empty(buf);
 341                 return lib_ring_buffer_snapshot(buf, &buf->cons_snapshot,
 342                                                 &buf->prod_snapshot);
 343         case RING_BUFFER_COMPAT_SNAPSHOT_GET_CONSUMED:
 344                 return compat_put_ulong(buf->cons_snapshot, arg);
 345         case RING_BUFFER_COMPAT_SNAPSHOT_GET_PRODUCED:
 346                 return compat_put_ulong(buf->prod_snapshot, arg);
 347         case RING_BUFFER_COMPAT_GET_SUBBUF:
 348         {
 349                 __u32 uconsume;
 350                 unsigned long consume;
 351                 long ret;
 352
 353                 ret = get_user(uconsume, (__u32 __user *) arg);
 354                 if (ret)
 355                         return ret; /* will return -EFAULT */
 356                 consume = buf->cons_snapshot;
 357                 consume &= ~0xFFFFFFFFL;
 358                 consume |= uconsume;
 359                 ret = lib_ring_buffer_get_subbuf(buf, consume);
 360                 if (!ret) {
 361                         /* Set file position to zero at each successful "get" */
 362                         filp->f_pos = 0;
 363                 }
 364                 return ret;
 365         }
 366         case RING_BUFFER_COMPAT_PUT_SUBBUF:
 367                 lib_ring_buffer_put_subbuf(buf);
 368                 return 0;
 369
 370         case RING_BUFFER_COMPAT_GET_NEXT_SUBBUF:
 371         {
 372                 long ret;
 373
 374                 ret = lib_ring_buffer_get_next_subbuf(buf);
 375                 if (!ret) {
 376                         /* Set file position to zero at each successful "get" */
 377                         filp->f_pos = 0;
 378                 }
 379                 return ret;
 380         }
 381         case RING_BUFFER_COMPAT_PUT_NEXT_SUBBUF:
 382                 lib_ring_buffer_put_next_subbuf(buf);
 383                 return 0;
 384         case RING_BUFFER_COMPAT_GET_SUBBUF_SIZE:
 385         {
 386                 unsigned long data_size;
 387
 388                 data_size = lib_ring_buffer_get_read_data_size(config, buf);
 389                 if (data_size > UINT_MAX)
 390                         return -EFBIG;
 391                 return compat_put_ulong(data_size, arg);
 392         }
 393         case RING_BUFFER_COMPAT_GET_PADDED_SUBBUF_SIZE:
 394         {
 395                 unsigned long size;
 396
 397                 size = lib_ring_buffer_get_read_data_size(config, buf);
 398                 size = PAGE_ALIGN(size);
 399                 if (size > UINT_MAX)
 400                         return -EFBIG;
 401                 return compat_put_ulong(size, arg);
 402         }
 403         case RING_BUFFER_COMPAT_GET_MAX_SUBBUF_SIZE:
 404                 if (chan->backend.subbuf_size > UINT_MAX)
 405                         return -EFBIG;
 406                 return compat_put_ulong(chan->backend.subbuf_size, arg);
 407         case RING_BUFFER_COMPAT_GET_MMAP_LEN:
 408         {
 409                 unsigned long mmap_buf_len;
 410
 411                 if (config->output != RING_BUFFER_MMAP)
 412                         return -EINVAL;
 413                 mmap_buf_len = chan->backend.buf_size;
 414                 if (chan->backend.extra_reader_sb)
 415                         mmap_buf_len += chan->backend.subbuf_size;
 416                 if (mmap_buf_len > UINT_MAX)
 417                         return -EFBIG;
 418                 return compat_put_ulong(mmap_buf_len, arg);
 419         }
 420         case RING_BUFFER_COMPAT_GET_MMAP_READ_OFFSET:
 421         {
 422                 unsigned long sb_bindex, read_offset;
 423
 424                 if (config->output != RING_BUFFER_MMAP)
 425                         return -EINVAL;
 426                 sb_bindex = subbuffer_id_get_index(config,
 427                                                    buf->backend.buf_rsb.id);
 428                 read_offset = buf->backend.array[sb_bindex]->mmap_offset;
 429                 if (read_offset > UINT_MAX)
 430                         return -EINVAL;
 431                 return compat_put_ulong(read_offset, arg);
 432         }
 433         case RING_BUFFER_COMPAT_FLUSH:
 434                 lib_ring_buffer_switch_remote(buf);
 435                 return 0;
 436         default:
 437                 return -ENOIOCTLCMD;
 438         }
 439 }
 440 EXPORT_SYMBOL_GPL(lib_ring_buffer_compat_ioctl);
 441
 442 static
 443 long vfs_lib_ring_buffer_compat_ioctl(struct file *filp, unsigned int cmd,
 444                                   unsigned long arg)
 445 {
 446         struct lib_ring_buffer *buf = filp->private_data;
 447
 448         return lib_ring_buffer_compat_ioctl(filp, cmd, arg, buf);
 449 }
 450 #endif
 451
 452 const struct file_operations lib_ring_buffer_file_operations = {
 453         .owner = THIS_MODULE,
 454         .open = vfs_lib_ring_buffer_open,
 455         .release = vfs_lib_ring_buffer_release,
 456         .poll = vfs_lib_ring_buffer_poll,
 457         .splice_read = vfs_lib_ring_buffer_splice_read,
 458         .mmap = vfs_lib_ring_buffer_mmap,
 459         .unlocked_ioctl = vfs_lib_ring_buffer_ioctl,
 460         .llseek = vfs_lib_ring_buffer_no_llseek,
 461 #ifdef CONFIG_COMPAT
 462         .compat_ioctl = vfs_lib_ring_buffer_compat_ioctl,
 463 #endif
 464 };
 465 EXPORT_SYMBOL_GPL(lib_ring_buffer_file_operations);
 466
 467 MODULE_LICENSE("GPL and additional rights");
 468 MODULE_AUTHOR("Mathieu Desnoyers");
 469 MODULE_DESCRIPTION("Ring Buffer Library VFS");
 470 MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "."
 471         __stringify(LTTNG_MODULES_MINOR_VERSION) "."
 472         __stringify(LTTNG_MODULES_PATCHLEVEL_VERSION)
 473         LTTNG_MODULES_EXTRAVERSION);