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