lib/ringbuffer/ring_buffer_vfs.c

   1 /* SPDX-License-Identifier: (GPL-2.0-only OR LGPL-2.1-only)
   2  *
   3  * ring_buffer_vfs.c
   4  *
   5  * Ring Buffer VFS file operations.
   6  *
   7  * Copyright (C) 2010-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/fs.h>
  12 #include <linux/compat.h>
  13
  14 #include <ringbuffer/backend.h>
  15 #include <ringbuffer/frontend.h>
  16 #include <ringbuffer/vfs.h>
  17 #include <wrapper/poll.h>
  18 #include <lttng-tracer.h>
  19
  20 static int put_ulong(unsigned long val, unsigned long arg)
  21 {
  22         return put_user(val, (unsigned long __user *)arg);
  23 }
  24
  25 #ifdef CONFIG_COMPAT
  26 static int compat_put_ulong(compat_ulong_t val, unsigned long arg)
  27 {
  28         return put_user(val, (compat_ulong_t __user *)compat_ptr(arg));
  29 }
  30 #endif
  31
  32 /*
  33  * This is not used by anonymous file descriptors. This code is left
  34  * there if we ever want to implement an inode with open() operation.
  35  */
  36 int lib_ring_buffer_open(struct inode *inode, struct file *file,
  37                 struct lib_ring_buffer *buf)
  38 {
  39         int ret;
  40
  41         if (!buf)
  42                 return -EINVAL;
  43
  44         ret = lib_ring_buffer_open_read(buf);
  45         if (ret)
  46                 return ret;
  47
  48         ret = nonseekable_open(inode, file);
  49         if (ret)
  50                 goto release_read;
  51         return 0;
  52
  53 release_read:
  54         lib_ring_buffer_release_read(buf);
  55         return ret;
  56 }
  57 EXPORT_SYMBOL_GPL(lib_ring_buffer_open);
  58
  59 /**
  60  *      vfs_lib_ring_buffer_open - ring buffer open file operation
  61  *      @inode: opened inode
  62  *      @file: opened file
  63  *
  64  *      Open implementation. Makes sure only one open instance of a buffer is
  65  *      done at a given moment.
  66  */
  67 static
  68 int vfs_lib_ring_buffer_open(struct inode *inode, struct file *file)
  69 {
  70         struct lib_ring_buffer *buf = inode->i_private;
  71
  72         file->private_data = buf;
  73         return lib_ring_buffer_open(inode, file, buf);
  74 }
  75
  76 int lib_ring_buffer_release(struct inode *inode, struct file *file,
  77                 struct lib_ring_buffer *buf)
  78 {
  79         lib_ring_buffer_release_read(buf);
  80
  81         return 0;
  82 }
  83 EXPORT_SYMBOL_GPL(lib_ring_buffer_release);
  84
  85 /**
  86  *      vfs_lib_ring_buffer_release - ring buffer release file operation
  87  *      @inode: opened inode
  88  *      @file: opened file
  89  *
  90  *      Release implementation.
  91  */
  92 static
  93 int vfs_lib_ring_buffer_release(struct inode *inode, struct file *file)
  94 {
  95         struct lib_ring_buffer *buf = file->private_data;
  96
  97         return lib_ring_buffer_release(inode, file, buf);
  98 }
  99
 100 unsigned int lib_ring_buffer_poll(struct file *filp, poll_table *wait,
 101                 struct lib_ring_buffer *buf)
 102 {
 103         unsigned int mask = 0;
 104         struct channel *chan = buf->backend.chan;
 105         const struct lib_ring_buffer_config *config = &chan->backend.config;
 106         int finalized, disabled;
 107
 108         if (filp->f_mode & FMODE_READ) {
 109                 poll_wait_set_exclusive(wait);
 110                 poll_wait(filp, &buf->read_wait, wait);
 111
 112                 finalized = lib_ring_buffer_is_finalized(config, buf);
 113                 disabled = lib_ring_buffer_channel_is_disabled(chan);
 114
 115                 /*
 116                  * lib_ring_buffer_is_finalized() contains a smp_rmb() ordering
 117                  * finalized load before offsets loads.
 118                  */
 119                 WARN_ON(atomic_long_read(&buf->active_readers) != 1);
 120 retry:
 121                 if (disabled)
 122                         return POLLERR;
 123
 124                 if (subbuf_trunc(lib_ring_buffer_get_offset(config, buf), chan)
 125                   - subbuf_trunc(lib_ring_buffer_get_consumed(config, buf), chan)
 126                   == 0) {
 127                         if (finalized)
 128                                 return POLLHUP;
 129                         else {
 130                                 /*
 131                                  * The memory barriers
 132                                  * __wait_event()/wake_up_interruptible() take
 133                                  * care of "raw_spin_is_locked" memory ordering.
 134                                  */
 135                                 if (raw_spin_is_locked(&buf->raw_tick_nohz_spinlock))
 136                                         goto retry;
 137                                 else
 138                                         return 0;
 139                         }
 140                 } else {
 141                         if (subbuf_trunc(lib_ring_buffer_get_offset(config, buf),
 142                                          chan)
 143                           - subbuf_trunc(lib_ring_buffer_get_consumed(config, buf),
 144                                          chan)
 145                           >= chan->backend.buf_size)
 146                                 return POLLPRI | POLLRDBAND;
 147                         else
 148                                 return POLLIN | POLLRDNORM;
 149                 }
 150         }
 151         return mask;
 152 }
 153 EXPORT_SYMBOL_GPL(lib_ring_buffer_poll);
 154
 155 /**
 156  *      vfs_lib_ring_buffer_poll - ring buffer poll file operation
 157  *      @filp: the file
 158  *      @wait: poll table
 159  *
 160  *      Poll implementation.
 161  */
 162 static
 163 unsigned int vfs_lib_ring_buffer_poll(struct file *filp, poll_table *wait)
 164 {
 165         struct lib_ring_buffer *buf = filp->private_data;
 166
 167         return lib_ring_buffer_poll(filp, wait, buf);
 168 }
 169
 170 long lib_ring_buffer_ioctl(struct file *filp, unsigned int cmd,
 171                 unsigned long arg, struct lib_ring_buffer *buf)
 172 {
 173         struct channel *chan = buf->backend.chan;
 174         const struct lib_ring_buffer_config *config = &chan->backend.config;
 175
 176         if (lib_ring_buffer_channel_is_disabled(chan))
 177                 return -EIO;
 178
 179         switch (cmd) {
 180         case RING_BUFFER_SNAPSHOT:
 181                 return lib_ring_buffer_snapshot(buf, &buf->cons_snapshot,
 182                                             &buf->prod_snapshot);
 183         case RING_BUFFER_SNAPSHOT_SAMPLE_POSITIONS:
 184                 return lib_ring_buffer_snapshot_sample_positions(buf,
 185                                 &buf->cons_snapshot, &buf->prod_snapshot);
 186         case RING_BUFFER_SNAPSHOT_GET_CONSUMED:
 187                 return put_ulong(buf->cons_snapshot, arg);
 188         case RING_BUFFER_SNAPSHOT_GET_PRODUCED:
 189                 return put_ulong(buf->prod_snapshot, arg);
 190         case RING_BUFFER_GET_SUBBUF:
 191         {
 192                 unsigned long uconsume;
 193                 long ret;
 194
 195                 ret = get_user(uconsume, (unsigned long __user *) arg);
 196                 if (ret)
 197                         return ret; /* will return -EFAULT */
 198                 ret = lib_ring_buffer_get_subbuf(buf, uconsume);
 199                 if (!ret) {
 200                         /* Set file position to zero at each successful "get" */
 201                         filp->f_pos = 0;
 202                 }
 203                 return ret;
 204         }
 205         case RING_BUFFER_PUT_SUBBUF:
 206                 lib_ring_buffer_put_subbuf(buf);
 207                 return 0;
 208
 209         case RING_BUFFER_GET_NEXT_SUBBUF:
 210         {
 211                 long ret;
 212
 213                 ret = lib_ring_buffer_get_next_subbuf(buf);
 214                 if (!ret) {
 215                         /* Set file position to zero at each successful "get" */
 216                         filp->f_pos = 0;
 217                 }
 218                 return ret;
 219         }
 220         case RING_BUFFER_PUT_NEXT_SUBBUF:
 221                 lib_ring_buffer_put_next_subbuf(buf);
 222                 return 0;
 223         case RING_BUFFER_GET_SUBBUF_SIZE:
 224                 return put_ulong(lib_ring_buffer_get_read_data_size(config, buf),
 225                                  arg);
 226         case RING_BUFFER_GET_PADDED_SUBBUF_SIZE:
 227         {
 228                 unsigned long size;
 229
 230                 size = lib_ring_buffer_get_read_data_size(config, buf);
 231                 size = PAGE_ALIGN(size);
 232                 return put_ulong(size, arg);
 233         }
 234         case RING_BUFFER_GET_MAX_SUBBUF_SIZE:
 235                 return put_ulong(chan->backend.subbuf_size, arg);
 236         case RING_BUFFER_GET_MMAP_LEN:
 237         {
 238                 unsigned long mmap_buf_len;
 239
 240                 if (config->output != RING_BUFFER_MMAP)
 241                         return -EINVAL;
 242                 mmap_buf_len = chan->backend.buf_size;
 243                 if (chan->backend.extra_reader_sb)
 244                         mmap_buf_len += chan->backend.subbuf_size;
 245                 if (mmap_buf_len > INT_MAX)
 246                         return -EFBIG;
 247                 return put_ulong(mmap_buf_len, arg);
 248         }
 249         case RING_BUFFER_GET_MMAP_READ_OFFSET:
 250         {
 251                 unsigned long sb_bindex;
 252
 253                 if (config->output != RING_BUFFER_MMAP)
 254                         return -EINVAL;
 255                 sb_bindex = subbuffer_id_get_index(config,
 256                                                    buf->backend.buf_rsb.id);
 257                 return put_ulong(buf->backend.array[sb_bindex]->mmap_offset,
 258                                  arg);
 259         }
 260         case RING_BUFFER_FLUSH:
 261                 lib_ring_buffer_switch_remote(buf);
 262                 return 0;
 263         case RING_BUFFER_FLUSH_EMPTY:
 264                 lib_ring_buffer_switch_remote_empty(buf);
 265                 return 0;
 266         case RING_BUFFER_CLEAR:
 267                 lib_ring_buffer_clear(buf);
 268                 return 0;
 269         default:
 270                 return -ENOIOCTLCMD;
 271         }
 272 }
 273 EXPORT_SYMBOL_GPL(lib_ring_buffer_ioctl);
 274
 275 /**
 276  *      vfs_lib_ring_buffer_ioctl - control ring buffer reader synchronization
 277  *
 278  *      @filp: the file
 279  *      @cmd: the command
 280  *      @arg: command arg
 281  *
 282  *      This ioctl implements commands necessary for producer/consumer
 283  *      and flight recorder reader interaction :
 284  *      RING_BUFFER_GET_NEXT_SUBBUF
 285  *              Get the next sub-buffer that can be read. It never blocks.
 286  *      RING_BUFFER_PUT_NEXT_SUBBUF
 287  *              Release the currently read sub-buffer.
 288  *      RING_BUFFER_GET_SUBBUF_SIZE
 289  *              returns the size of the current sub-buffer.
 290  *      RING_BUFFER_GET_MAX_SUBBUF_SIZE
 291  *              returns the maximum size for sub-buffers.
 292  *      RING_BUFFER_GET_NUM_SUBBUF
 293  *              returns the number of reader-visible sub-buffers in the per cpu
 294  *              channel (for mmap).
 295  *      RING_BUFFER_GET_MMAP_READ_OFFSET
 296  *              returns the offset of the subbuffer belonging to the reader.
 297  *              Should only be used for mmap clients.
 298  */
 299 static
 300 long vfs_lib_ring_buffer_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 301 {
 302         struct lib_ring_buffer *buf = filp->private_data;
 303
 304         return lib_ring_buffer_ioctl(filp, cmd, arg, buf);
 305 }
 306
 307 #ifdef CONFIG_COMPAT
 308 long lib_ring_buffer_compat_ioctl(struct file *filp, unsigned int cmd,
 309                 unsigned long arg, struct lib_ring_buffer *buf)
 310 {
 311         struct channel *chan = buf->backend.chan;
 312         const struct lib_ring_buffer_config *config = &chan->backend.config;
 313
 314         if (lib_ring_buffer_channel_is_disabled(chan))
 315                 return -EIO;
 316
 317         switch (cmd) {
 318         case RING_BUFFER_COMPAT_SNAPSHOT:
 319                 return lib_ring_buffer_snapshot(buf, &buf->cons_snapshot,
 320                                                 &buf->prod_snapshot);
 321         case RING_BUFFER_COMPAT_SNAPSHOT_SAMPLE_POSITIONS:
 322                 return lib_ring_buffer_snapshot_sample_positions(buf,
 323                                 &buf->cons_snapshot, &buf->prod_snapshot);
 324         case RING_BUFFER_COMPAT_SNAPSHOT_GET_CONSUMED:
 325                 return compat_put_ulong(buf->cons_snapshot, arg);
 326         case RING_BUFFER_COMPAT_SNAPSHOT_GET_PRODUCED:
 327                 return compat_put_ulong(buf->prod_snapshot, arg);
 328         case RING_BUFFER_COMPAT_GET_SUBBUF:
 329         {
 330                 __u32 uconsume;
 331                 unsigned long consume;
 332                 long ret;
 333
 334                 ret = get_user(uconsume, (__u32 __user *) arg);
 335                 if (ret)
 336                         return ret; /* will return -EFAULT */
 337                 consume = buf->cons_snapshot;
 338                 consume &= ~0xFFFFFFFFL;
 339                 consume |= uconsume;
 340                 ret = lib_ring_buffer_get_subbuf(buf, consume);
 341                 if (!ret) {
 342                         /* Set file position to zero at each successful "get" */
 343                         filp->f_pos = 0;
 344                 }
 345                 return ret;
 346         }
 347         case RING_BUFFER_COMPAT_PUT_SUBBUF:
 348                 lib_ring_buffer_put_subbuf(buf);
 349                 return 0;
 350
 351         case RING_BUFFER_COMPAT_GET_NEXT_SUBBUF:
 352         {
 353                 long ret;
 354
 355                 ret = lib_ring_buffer_get_next_subbuf(buf);
 356                 if (!ret) {
 357                         /* Set file position to zero at each successful "get" */
 358                         filp->f_pos = 0;
 359                 }
 360                 return ret;
 361         }
 362         case RING_BUFFER_COMPAT_PUT_NEXT_SUBBUF:
 363                 lib_ring_buffer_put_next_subbuf(buf);
 364                 return 0;
 365         case RING_BUFFER_COMPAT_GET_SUBBUF_SIZE:
 366         {
 367                 unsigned long data_size;
 368
 369                 data_size = lib_ring_buffer_get_read_data_size(config, buf);
 370                 if (data_size > UINT_MAX)
 371                         return -EFBIG;
 372                 return compat_put_ulong(data_size, arg);
 373         }
 374         case RING_BUFFER_COMPAT_GET_PADDED_SUBBUF_SIZE:
 375         {
 376                 unsigned long size;
 377
 378                 size = lib_ring_buffer_get_read_data_size(config, buf);
 379                 size = PAGE_ALIGN(size);
 380                 if (size > UINT_MAX)
 381                         return -EFBIG;
 382                 return compat_put_ulong(size, arg);
 383         }
 384         case RING_BUFFER_COMPAT_GET_MAX_SUBBUF_SIZE:
 385                 if (chan->backend.subbuf_size > UINT_MAX)
 386                         return -EFBIG;
 387                 return compat_put_ulong(chan->backend.subbuf_size, arg);
 388         case RING_BUFFER_COMPAT_GET_MMAP_LEN:
 389         {
 390                 unsigned long mmap_buf_len;
 391
 392                 if (config->output != RING_BUFFER_MMAP)
 393                         return -EINVAL;
 394                 mmap_buf_len = chan->backend.buf_size;
 395                 if (chan->backend.extra_reader_sb)
 396                         mmap_buf_len += chan->backend.subbuf_size;
 397                 if (mmap_buf_len > UINT_MAX)
 398                         return -EFBIG;
 399                 return compat_put_ulong(mmap_buf_len, arg);
 400         }
 401         case RING_BUFFER_COMPAT_GET_MMAP_READ_OFFSET:
 402         {
 403                 unsigned long sb_bindex, read_offset;
 404
 405                 if (config->output != RING_BUFFER_MMAP)
 406                         return -EINVAL;
 407                 sb_bindex = subbuffer_id_get_index(config,
 408                                                    buf->backend.buf_rsb.id);
 409                 read_offset = buf->backend.array[sb_bindex]->mmap_offset;
 410                 if (read_offset > UINT_MAX)
 411                         return -EINVAL;
 412                 return compat_put_ulong(read_offset, arg);
 413         }
 414         case RING_BUFFER_COMPAT_FLUSH:
 415                 lib_ring_buffer_switch_remote(buf);
 416                 return 0;
 417         case RING_BUFFER_COMPAT_FLUSH_EMPTY:
 418                 lib_ring_buffer_switch_remote_empty(buf);
 419                 return 0;
 420         case RING_BUFFER_COMPAT_CLEAR:
 421                 lib_ring_buffer_clear(buf);
 422                 return 0;
 423         default:
 424                 return -ENOIOCTLCMD;
 425         }
 426 }
 427 EXPORT_SYMBOL_GPL(lib_ring_buffer_compat_ioctl);
 428
 429 static
 430 long vfs_lib_ring_buffer_compat_ioctl(struct file *filp, unsigned int cmd,
 431                                   unsigned long arg)
 432 {
 433         struct lib_ring_buffer *buf = filp->private_data;
 434
 435         return lib_ring_buffer_compat_ioctl(filp, cmd, arg, buf);
 436 }
 437 #endif
 438
 439 const struct file_operations lib_ring_buffer_file_operations = {
 440         .owner = THIS_MODULE,
 441         .open = vfs_lib_ring_buffer_open,
 442         .release = vfs_lib_ring_buffer_release,
 443         .poll = vfs_lib_ring_buffer_poll,
 444         .splice_read = vfs_lib_ring_buffer_splice_read,
 445         .mmap = vfs_lib_ring_buffer_mmap,
 446         .unlocked_ioctl = vfs_lib_ring_buffer_ioctl,
 447         .llseek = vfs_lib_ring_buffer_no_llseek,
 448 #ifdef CONFIG_COMPAT
 449         .compat_ioctl = vfs_lib_ring_buffer_compat_ioctl,
 450 #endif
 451 };
 452 EXPORT_SYMBOL_GPL(lib_ring_buffer_file_operations);
 453
 454 MODULE_LICENSE("GPL and additional rights");
 455 MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
 456 MODULE_DESCRIPTION("LTTng ring buffer library");
 457 MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "."
 458         __stringify(LTTNG_MODULES_MINOR_VERSION) "."
 459         __stringify(LTTNG_MODULES_PATCHLEVEL_VERSION)
 460         LTTNG_MODULES_EXTRAVERSION);