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