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_SAMPLE_POSITIONS:
 206                 return lib_ring_buffer_snapshot_sample_positions(buf,
 207                                 &buf->cons_snapshot, &buf->prod_snapshot);
 208         case RING_BUFFER_SNAPSHOT_GET_CONSUMED:
 209                 return put_ulong(buf->cons_snapshot, arg);
 210         case RING_BUFFER_SNAPSHOT_GET_PRODUCED:
 211                 return put_ulong(buf->prod_snapshot, arg);
 212         case RING_BUFFER_GET_SUBBUF:
 213         {
 214                 unsigned long uconsume;
 215                 long ret;
 216
 217                 ret = get_user(uconsume, (unsigned long __user *) arg);
 218                 if (ret)
 219                         return ret; /* will return -EFAULT */
 220                 ret = lib_ring_buffer_get_subbuf(buf, uconsume);
 221                 if (!ret) {
 222                         /* Set file position to zero at each successful "get" */
 223                         filp->f_pos = 0;
 224                 }
 225                 return ret;
 226         }
 227         case RING_BUFFER_PUT_SUBBUF:
 228                 lib_ring_buffer_put_subbuf(buf);
 229                 return 0;
 230
 231         case RING_BUFFER_GET_NEXT_SUBBUF:
 232         {
 233                 long ret;
 234
 235                 ret = lib_ring_buffer_get_next_subbuf(buf);
 236                 if (!ret) {
 237                         /* Set file position to zero at each successful "get" */
 238                         filp->f_pos = 0;
 239                 }
 240                 return ret;
 241         }
 242         case RING_BUFFER_PUT_NEXT_SUBBUF:
 243                 lib_ring_buffer_put_next_subbuf(buf);
 244                 return 0;
 245         case RING_BUFFER_GET_SUBBUF_SIZE:
 246                 return put_ulong(lib_ring_buffer_get_read_data_size(config, buf),
 247                                  arg);
 248         case RING_BUFFER_GET_PADDED_SUBBUF_SIZE:
 249         {
 250                 unsigned long size;
 251
 252                 size = lib_ring_buffer_get_read_data_size(config, buf);
 253                 size = PAGE_ALIGN(size);
 254                 return put_ulong(size, arg);
 255         }
 256         case RING_BUFFER_GET_MAX_SUBBUF_SIZE:
 257                 return put_ulong(chan->backend.subbuf_size, arg);
 258         case RING_BUFFER_GET_MMAP_LEN:
 259         {
 260                 unsigned long mmap_buf_len;
 261
 262                 if (config->output != RING_BUFFER_MMAP)
 263                         return -EINVAL;
 264                 mmap_buf_len = chan->backend.buf_size;
 265                 if (chan->backend.extra_reader_sb)
 266                         mmap_buf_len += chan->backend.subbuf_size;
 267                 if (mmap_buf_len > INT_MAX)
 268                         return -EFBIG;
 269                 return put_ulong(mmap_buf_len, arg);
 270         }
 271         case RING_BUFFER_GET_MMAP_READ_OFFSET:
 272         {
 273                 unsigned long sb_bindex;
 274
 275                 if (config->output != RING_BUFFER_MMAP)
 276                         return -EINVAL;
 277                 sb_bindex = subbuffer_id_get_index(config,
 278                                                    buf->backend.buf_rsb.id);
 279                 return put_ulong(buf->backend.array[sb_bindex]->mmap_offset,
 280                                  arg);
 281         }
 282         case RING_BUFFER_FLUSH:
 283                 lib_ring_buffer_switch_remote(buf);
 284                 return 0;
 285         default:
 286                 return -ENOIOCTLCMD;
 287         }
 288 }
 289 EXPORT_SYMBOL_GPL(lib_ring_buffer_ioctl);
 290
 291 /**
 292  *      vfs_lib_ring_buffer_ioctl - control ring buffer reader synchronization
 293  *
 294  *      @filp: the file
 295  *      @cmd: the command
 296  *      @arg: command arg
 297  *
 298  *      This ioctl implements commands necessary for producer/consumer
 299  *      and flight recorder reader interaction :
 300  *      RING_BUFFER_GET_NEXT_SUBBUF
 301  *              Get the next sub-buffer that can be read. It never blocks.
 302  *      RING_BUFFER_PUT_NEXT_SUBBUF
 303  *              Release the currently read sub-buffer.
 304  *      RING_BUFFER_GET_SUBBUF_SIZE
 305  *              returns the size of the current sub-buffer.
 306  *      RING_BUFFER_GET_MAX_SUBBUF_SIZE
 307  *              returns the maximum size for sub-buffers.
 308  *      RING_BUFFER_GET_NUM_SUBBUF
 309  *              returns the number of reader-visible sub-buffers in the per cpu
 310  *              channel (for mmap).
 311  *      RING_BUFFER_GET_MMAP_READ_OFFSET
 312  *              returns the offset of the subbuffer belonging to the reader.
 313  *              Should only be used for mmap clients.
 314  */
 315 static
 316 long vfs_lib_ring_buffer_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 317 {
 318         struct lib_ring_buffer *buf = filp->private_data;
 319
 320         return lib_ring_buffer_ioctl(filp, cmd, arg, buf);
 321 }
 322
 323 #ifdef CONFIG_COMPAT
 324 long lib_ring_buffer_compat_ioctl(struct file *filp, unsigned int cmd,
 325                 unsigned long arg, struct lib_ring_buffer *buf)
 326 {
 327         struct channel *chan = buf->backend.chan;
 328         const struct lib_ring_buffer_config *config = &chan->backend.config;
 329
 330         if (lib_ring_buffer_channel_is_disabled(chan))
 331                 return -EIO;
 332
 333         switch (cmd) {
 334         case RING_BUFFER_COMPAT_SNAPSHOT:
 335                 /*
 336                  * First, ensure we perform a "final" flush onto the
 337                  * stream.  This will ensure we create a packet of
 338                  * padding if we encounter an empty packet. This ensures
 339                  * the time-stamps right before the snapshot is used as
 340                  * end of packet timestamp.
 341                  */
 342                 if (!buf->quiescent)
 343                         lib_ring_buffer_switch_remote_empty(buf);
 344                 return lib_ring_buffer_snapshot(buf, &buf->cons_snapshot,
 345                                                 &buf->prod_snapshot);
 346         case RING_BUFFER_COMPAT_SNAPSHOT_SAMPLE_POSITIONS:
 347                 return lib_ring_buffer_snapshot_sample_positions(buf,
 348                                 &buf->cons_snapshot, &buf->prod_snapshot);
 349         case RING_BUFFER_COMPAT_SNAPSHOT_GET_CONSUMED:
 350                 return compat_put_ulong(buf->cons_snapshot, arg);
 351         case RING_BUFFER_COMPAT_SNAPSHOT_GET_PRODUCED:
 352                 return compat_put_ulong(buf->prod_snapshot, arg);
 353         case RING_BUFFER_COMPAT_GET_SUBBUF:
 354         {
 355                 __u32 uconsume;
 356                 unsigned long consume;
 357                 long ret;
 358
 359                 ret = get_user(uconsume, (__u32 __user *) arg);
 360                 if (ret)
 361                         return ret; /* will return -EFAULT */
 362                 consume = buf->cons_snapshot;
 363                 consume &= ~0xFFFFFFFFL;
 364                 consume |= uconsume;
 365                 ret = lib_ring_buffer_get_subbuf(buf, consume);
 366                 if (!ret) {
 367                         /* Set file position to zero at each successful "get" */
 368                         filp->f_pos = 0;
 369                 }
 370                 return ret;
 371         }
 372         case RING_BUFFER_COMPAT_PUT_SUBBUF:
 373                 lib_ring_buffer_put_subbuf(buf);
 374                 return 0;
 375
 376         case RING_BUFFER_COMPAT_GET_NEXT_SUBBUF:
 377         {
 378                 long ret;
 379
 380                 ret = lib_ring_buffer_get_next_subbuf(buf);
 381                 if (!ret) {
 382                         /* Set file position to zero at each successful "get" */
 383                         filp->f_pos = 0;
 384                 }
 385                 return ret;
 386         }
 387         case RING_BUFFER_COMPAT_PUT_NEXT_SUBBUF:
 388                 lib_ring_buffer_put_next_subbuf(buf);
 389                 return 0;
 390         case RING_BUFFER_COMPAT_GET_SUBBUF_SIZE:
 391         {
 392                 unsigned long data_size;
 393
 394                 data_size = lib_ring_buffer_get_read_data_size(config, buf);
 395                 if (data_size > UINT_MAX)
 396                         return -EFBIG;
 397                 return compat_put_ulong(data_size, arg);
 398         }
 399         case RING_BUFFER_COMPAT_GET_PADDED_SUBBUF_SIZE:
 400         {
 401                 unsigned long size;
 402
 403                 size = lib_ring_buffer_get_read_data_size(config, buf);
 404                 size = PAGE_ALIGN(size);
 405                 if (size > UINT_MAX)
 406                         return -EFBIG;
 407                 return compat_put_ulong(size, arg);
 408         }
 409         case RING_BUFFER_COMPAT_GET_MAX_SUBBUF_SIZE:
 410                 if (chan->backend.subbuf_size > UINT_MAX)
 411                         return -EFBIG;
 412                 return compat_put_ulong(chan->backend.subbuf_size, arg);
 413         case RING_BUFFER_COMPAT_GET_MMAP_LEN:
 414         {
 415                 unsigned long mmap_buf_len;
 416
 417                 if (config->output != RING_BUFFER_MMAP)
 418                         return -EINVAL;
 419                 mmap_buf_len = chan->backend.buf_size;
 420                 if (chan->backend.extra_reader_sb)
 421                         mmap_buf_len += chan->backend.subbuf_size;
 422                 if (mmap_buf_len > UINT_MAX)
 423                         return -EFBIG;
 424                 return compat_put_ulong(mmap_buf_len, arg);
 425         }
 426         case RING_BUFFER_COMPAT_GET_MMAP_READ_OFFSET:
 427         {
 428                 unsigned long sb_bindex, read_offset;
 429
 430                 if (config->output != RING_BUFFER_MMAP)
 431                         return -EINVAL;
 432                 sb_bindex = subbuffer_id_get_index(config,
 433                                                    buf->backend.buf_rsb.id);
 434                 read_offset = buf->backend.array[sb_bindex]->mmap_offset;
 435                 if (read_offset > UINT_MAX)
 436                         return -EINVAL;
 437                 return compat_put_ulong(read_offset, arg);
 438         }
 439         case RING_BUFFER_COMPAT_FLUSH:
 440                 lib_ring_buffer_switch_remote(buf);
 441                 return 0;
 442         default:
 443                 return -ENOIOCTLCMD;
 444         }
 445 }
 446 EXPORT_SYMBOL_GPL(lib_ring_buffer_compat_ioctl);
 447
 448 static
 449 long vfs_lib_ring_buffer_compat_ioctl(struct file *filp, unsigned int cmd,
 450                                   unsigned long arg)
 451 {
 452         struct lib_ring_buffer *buf = filp->private_data;
 453
 454         return lib_ring_buffer_compat_ioctl(filp, cmd, arg, buf);
 455 }
 456 #endif
 457
 458 const struct file_operations lib_ring_buffer_file_operations = {
 459         .owner = THIS_MODULE,
 460         .open = vfs_lib_ring_buffer_open,
 461         .release = vfs_lib_ring_buffer_release,
 462         .poll = vfs_lib_ring_buffer_poll,
 463         .splice_read = vfs_lib_ring_buffer_splice_read,
 464         .mmap = vfs_lib_ring_buffer_mmap,
 465         .unlocked_ioctl = vfs_lib_ring_buffer_ioctl,
 466         .llseek = vfs_lib_ring_buffer_no_llseek,
 467 #ifdef CONFIG_COMPAT
 468         .compat_ioctl = vfs_lib_ring_buffer_compat_ioctl,
 469 #endif
 470 };
 471 EXPORT_SYMBOL_GPL(lib_ring_buffer_file_operations);
 472
 473 MODULE_LICENSE("GPL and additional rights");
 474 MODULE_AUTHOR("Mathieu Desnoyers");
 475 MODULE_DESCRIPTION("Ring Buffer Library VFS");
 476 MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "."
 477         __stringify(LTTNG_MODULES_MINOR_VERSION) "."
 478         __stringify(LTTNG_MODULES_PATCHLEVEL_VERSION)
 479         LTTNG_MODULES_EXTRAVERSION);