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                 return lib_ring_buffer_snapshot(buf, &buf->cons_snapshot,
 195                                             &buf->prod_snapshot);
 196         case RING_BUFFER_SNAPSHOT_SAMPLE_POSITIONS:
 197                 return lib_ring_buffer_snapshot_sample_positions(buf,
 198                                 &buf->cons_snapshot, &buf->prod_snapshot);
 199         case RING_BUFFER_SNAPSHOT_GET_CONSUMED:
 200                 return put_ulong(buf->cons_snapshot, arg);
 201         case RING_BUFFER_SNAPSHOT_GET_PRODUCED:
 202                 return put_ulong(buf->prod_snapshot, arg);
 203         case RING_BUFFER_GET_SUBBUF:
 204         {
 205                 unsigned long uconsume;
 206                 long ret;
 207
 208                 ret = get_user(uconsume, (unsigned long __user *) arg);
 209                 if (ret)
 210                         return ret; /* will return -EFAULT */
 211                 ret = lib_ring_buffer_get_subbuf(buf, uconsume);
 212                 if (!ret) {
 213                         /* Set file position to zero at each successful "get" */
 214                         filp->f_pos = 0;
 215                 }
 216                 return ret;
 217         }
 218         case RING_BUFFER_PUT_SUBBUF:
 219                 lib_ring_buffer_put_subbuf(buf);
 220                 return 0;
 221
 222         case RING_BUFFER_GET_NEXT_SUBBUF:
 223         {
 224                 long ret;
 225
 226                 ret = lib_ring_buffer_get_next_subbuf(buf);
 227                 if (!ret) {
 228                         /* Set file position to zero at each successful "get" */
 229                         filp->f_pos = 0;
 230                 }
 231                 return ret;
 232         }
 233         case RING_BUFFER_PUT_NEXT_SUBBUF:
 234                 lib_ring_buffer_put_next_subbuf(buf);
 235                 return 0;
 236         case RING_BUFFER_GET_SUBBUF_SIZE:
 237                 return put_ulong(lib_ring_buffer_get_read_data_size(config, buf),
 238                                  arg);
 239         case RING_BUFFER_GET_PADDED_SUBBUF_SIZE:
 240         {
 241                 unsigned long size;
 242
 243                 size = lib_ring_buffer_get_read_data_size(config, buf);
 244                 size = PAGE_ALIGN(size);
 245                 return put_ulong(size, arg);
 246         }
 247         case RING_BUFFER_GET_MAX_SUBBUF_SIZE:
 248                 return put_ulong(chan->backend.subbuf_size, arg);
 249         case RING_BUFFER_GET_MMAP_LEN:
 250         {
 251                 unsigned long mmap_buf_len;
 252
 253                 if (config->output != RING_BUFFER_MMAP)
 254                         return -EINVAL;
 255                 mmap_buf_len = chan->backend.buf_size;
 256                 if (chan->backend.extra_reader_sb)
 257                         mmap_buf_len += chan->backend.subbuf_size;
 258                 if (mmap_buf_len > INT_MAX)
 259                         return -EFBIG;
 260                 return put_ulong(mmap_buf_len, arg);
 261         }
 262         case RING_BUFFER_GET_MMAP_READ_OFFSET:
 263         {
 264                 unsigned long sb_bindex;
 265
 266                 if (config->output != RING_BUFFER_MMAP)
 267                         return -EINVAL;
 268                 sb_bindex = subbuffer_id_get_index(config,
 269                                                    buf->backend.buf_rsb.id);
 270                 return put_ulong(buf->backend.array[sb_bindex]->mmap_offset,
 271                                  arg);
 272         }
 273         case RING_BUFFER_FLUSH:
 274                 lib_ring_buffer_switch_remote(buf);
 275                 return 0;
 276         default:
 277                 return -ENOIOCTLCMD;
 278         }
 279 }
 280 EXPORT_SYMBOL_GPL(lib_ring_buffer_ioctl);
 281
 282 /**
 283  *      vfs_lib_ring_buffer_ioctl - control ring buffer reader synchronization
 284  *
 285  *      @filp: the file
 286  *      @cmd: the command
 287  *      @arg: command arg
 288  *
 289  *      This ioctl implements commands necessary for producer/consumer
 290  *      and flight recorder reader interaction :
 291  *      RING_BUFFER_GET_NEXT_SUBBUF
 292  *              Get the next sub-buffer that can be read. It never blocks.
 293  *      RING_BUFFER_PUT_NEXT_SUBBUF
 294  *              Release the currently read sub-buffer.
 295  *      RING_BUFFER_GET_SUBBUF_SIZE
 296  *              returns the size of the current sub-buffer.
 297  *      RING_BUFFER_GET_MAX_SUBBUF_SIZE
 298  *              returns the maximum size for sub-buffers.
 299  *      RING_BUFFER_GET_NUM_SUBBUF
 300  *              returns the number of reader-visible sub-buffers in the per cpu
 301  *              channel (for mmap).
 302  *      RING_BUFFER_GET_MMAP_READ_OFFSET
 303  *              returns the offset of the subbuffer belonging to the reader.
 304  *              Should only be used for mmap clients.
 305  */
 306 static
 307 long vfs_lib_ring_buffer_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 308 {
 309         struct lib_ring_buffer *buf = filp->private_data;
 310
 311         return lib_ring_buffer_ioctl(filp, cmd, arg, buf);
 312 }
 313
 314 #ifdef CONFIG_COMPAT
 315 long lib_ring_buffer_compat_ioctl(struct file *filp, unsigned int cmd,
 316                 unsigned long arg, struct lib_ring_buffer *buf)
 317 {
 318         struct channel *chan = buf->backend.chan;
 319         const struct lib_ring_buffer_config *config = &chan->backend.config;
 320
 321         if (lib_ring_buffer_channel_is_disabled(chan))
 322                 return -EIO;
 323
 324         switch (cmd) {
 325         case RING_BUFFER_COMPAT_SNAPSHOT:
 326                 return lib_ring_buffer_snapshot(buf, &buf->cons_snapshot,
 327                                                 &buf->prod_snapshot);
 328         case RING_BUFFER_COMPAT_SNAPSHOT_SAMPLE_POSITIONS:
 329                 return lib_ring_buffer_snapshot_sample_positions(buf,
 330                                 &buf->cons_snapshot, &buf->prod_snapshot);
 331         case RING_BUFFER_COMPAT_SNAPSHOT_GET_CONSUMED:
 332                 return compat_put_ulong(buf->cons_snapshot, arg);
 333         case RING_BUFFER_COMPAT_SNAPSHOT_GET_PRODUCED:
 334                 return compat_put_ulong(buf->prod_snapshot, arg);
 335         case RING_BUFFER_COMPAT_GET_SUBBUF:
 336         {
 337                 __u32 uconsume;
 338                 unsigned long consume;
 339                 long ret;
 340
 341                 ret = get_user(uconsume, (__u32 __user *) arg);
 342                 if (ret)
 343                         return ret; /* will return -EFAULT */
 344                 consume = buf->cons_snapshot;
 345                 consume &= ~0xFFFFFFFFL;
 346                 consume |= uconsume;
 347                 ret = lib_ring_buffer_get_subbuf(buf, consume);
 348                 if (!ret) {
 349                         /* Set file position to zero at each successful "get" */
 350                         filp->f_pos = 0;
 351                 }
 352                 return ret;
 353         }
 354         case RING_BUFFER_COMPAT_PUT_SUBBUF:
 355                 lib_ring_buffer_put_subbuf(buf);
 356                 return 0;
 357
 358         case RING_BUFFER_COMPAT_GET_NEXT_SUBBUF:
 359         {
 360                 long ret;
 361
 362                 ret = lib_ring_buffer_get_next_subbuf(buf);
 363                 if (!ret) {
 364                         /* Set file position to zero at each successful "get" */
 365                         filp->f_pos = 0;
 366                 }
 367                 return ret;
 368         }
 369         case RING_BUFFER_COMPAT_PUT_NEXT_SUBBUF:
 370                 lib_ring_buffer_put_next_subbuf(buf);
 371                 return 0;
 372         case RING_BUFFER_COMPAT_GET_SUBBUF_SIZE:
 373         {
 374                 unsigned long data_size;
 375
 376                 data_size = lib_ring_buffer_get_read_data_size(config, buf);
 377                 if (data_size > UINT_MAX)
 378                         return -EFBIG;
 379                 return compat_put_ulong(data_size, arg);
 380         }
 381         case RING_BUFFER_COMPAT_GET_PADDED_SUBBUF_SIZE:
 382         {
 383                 unsigned long size;
 384
 385                 size = lib_ring_buffer_get_read_data_size(config, buf);
 386                 size = PAGE_ALIGN(size);
 387                 if (size > UINT_MAX)
 388                         return -EFBIG;
 389                 return compat_put_ulong(size, arg);
 390         }
 391         case RING_BUFFER_COMPAT_GET_MAX_SUBBUF_SIZE:
 392                 if (chan->backend.subbuf_size > UINT_MAX)
 393                         return -EFBIG;
 394                 return compat_put_ulong(chan->backend.subbuf_size, arg);
 395         case RING_BUFFER_COMPAT_GET_MMAP_LEN:
 396         {
 397                 unsigned long mmap_buf_len;
 398
 399                 if (config->output != RING_BUFFER_MMAP)
 400                         return -EINVAL;
 401                 mmap_buf_len = chan->backend.buf_size;
 402                 if (chan->backend.extra_reader_sb)
 403                         mmap_buf_len += chan->backend.subbuf_size;
 404                 if (mmap_buf_len > UINT_MAX)
 405                         return -EFBIG;
 406                 return compat_put_ulong(mmap_buf_len, arg);
 407         }
 408         case RING_BUFFER_COMPAT_GET_MMAP_READ_OFFSET:
 409         {
 410                 unsigned long sb_bindex, read_offset;
 411
 412                 if (config->output != RING_BUFFER_MMAP)
 413                         return -EINVAL;
 414                 sb_bindex = subbuffer_id_get_index(config,
 415                                                    buf->backend.buf_rsb.id);
 416                 read_offset = buf->backend.array[sb_bindex]->mmap_offset;
 417                 if (read_offset > UINT_MAX)
 418                         return -EINVAL;
 419                 return compat_put_ulong(read_offset, arg);
 420         }
 421         case RING_BUFFER_COMPAT_FLUSH:
 422                 lib_ring_buffer_switch_remote(buf);
 423                 return 0;
 424         default:
 425                 return -ENOIOCTLCMD;
 426         }
 427 }
 428 EXPORT_SYMBOL_GPL(lib_ring_buffer_compat_ioctl);
 429
 430 static
 431 long vfs_lib_ring_buffer_compat_ioctl(struct file *filp, unsigned int cmd,
 432                                   unsigned long arg)
 433 {
 434         struct lib_ring_buffer *buf = filp->private_data;
 435
 436         return lib_ring_buffer_compat_ioctl(filp, cmd, arg, buf);
 437 }
 438 #endif
 439
 440 const struct file_operations lib_ring_buffer_file_operations = {
 441         .owner = THIS_MODULE,
 442         .open = vfs_lib_ring_buffer_open,
 443         .release = vfs_lib_ring_buffer_release,
 444         .poll = vfs_lib_ring_buffer_poll,
 445         .splice_read = vfs_lib_ring_buffer_splice_read,
 446         .mmap = vfs_lib_ring_buffer_mmap,
 447         .unlocked_ioctl = vfs_lib_ring_buffer_ioctl,
 448         .llseek = vfs_lib_ring_buffer_no_llseek,
 449 #ifdef CONFIG_COMPAT
 450         .compat_ioctl = vfs_lib_ring_buffer_compat_ioctl,
 451 #endif
 452 };
 453 EXPORT_SYMBOL_GPL(lib_ring_buffer_file_operations);
 454
 455 MODULE_LICENSE("GPL and additional rights");
 456 MODULE_AUTHOR("Mathieu Desnoyers");
 457 MODULE_DESCRIPTION("Ring Buffer Library VFS");
 458 MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "."
 459         __stringify(LTTNG_MODULES_MINOR_VERSION) "."
 460         __stringify(LTTNG_MODULES_PATCHLEVEL_VERSION)
 461         LTTNG_MODULES_EXTRAVERSION);