drivers/staging/lttng/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
  32 static int put_ulong(unsigned long val, unsigned long arg)
  33 {
  34         return put_user(val, (unsigned long __user *)arg);
  35 }
  36
  37 #ifdef CONFIG_COMPAT
  38 static int compat_put_ulong(compat_ulong_t val, unsigned long arg)
  39 {
  40         return put_user(val, (compat_ulong_t __user *)compat_ptr(arg));
  41 }
  42 #endif
  43
  44 /*
  45  * This is not used by anonymous file descriptors. This code is left
  46  * there if we ever want to implement an inode with open() operation.
  47  */
  48 int lib_ring_buffer_open(struct inode *inode, struct file *file,
  49                 struct lib_ring_buffer *buf)
  50 {
  51         int ret;
  52
  53         if (!buf)
  54                 return -EINVAL;
  55
  56         ret = lib_ring_buffer_open_read(buf);
  57         if (ret)
  58                 return ret;
  59
  60         ret = nonseekable_open(inode, file);
  61         if (ret)
  62                 goto release_read;
  63         return 0;
  64
  65 release_read:
  66         lib_ring_buffer_release_read(buf);
  67         return ret;
  68 }
  69 EXPORT_SYMBOL_GPL(lib_ring_buffer_open);
  70
  71 /**
  72  *      vfs_lib_ring_buffer_open - ring buffer open file operation
  73  *      @inode: opened inode
  74  *      @file: opened file
  75  *
  76  *      Open implementation. Makes sure only one open instance of a buffer is
  77  *      done at a given moment.
  78  */
  79 static
  80 int vfs_lib_ring_buffer_open(struct inode *inode, struct file *file)
  81 {
  82         struct lib_ring_buffer *buf = inode->i_private;
  83
  84         file->private_data = buf;
  85         return lib_ring_buffer_open(inode, file, buf);
  86 }
  87
  88 int lib_ring_buffer_release(struct inode *inode, struct file *file,
  89                 struct lib_ring_buffer *buf)
  90 {
  91         lib_ring_buffer_release_read(buf);
  92
  93         return 0;
  94 }
  95 EXPORT_SYMBOL_GPL(lib_ring_buffer_release);
  96
  97 /**
  98  *      vfs_lib_ring_buffer_release - ring buffer release file operation
  99  *      @inode: opened inode
 100  *      @file: opened file
 101  *
 102  *      Release implementation.
 103  */
 104 static
 105 int vfs_lib_ring_buffer_release(struct inode *inode, struct file *file)
 106 {
 107         struct lib_ring_buffer *buf = file->private_data;
 108
 109         return lib_ring_buffer_release(inode, file, buf);
 110 }
 111
 112 unsigned int lib_ring_buffer_poll(struct file *filp, poll_table *wait,
 113                 struct lib_ring_buffer *buf)
 114 {
 115         unsigned int mask = 0;
 116         struct channel *chan = buf->backend.chan;
 117         const struct lib_ring_buffer_config *config = &chan->backend.config;
 118         int finalized, disabled;
 119
 120         if (filp->f_mode & FMODE_READ) {
 121                 poll_wait_set_exclusive(wait);
 122                 poll_wait(filp, &buf->read_wait, wait);
 123
 124                 finalized = lib_ring_buffer_is_finalized(config, buf);
 125                 disabled = lib_ring_buffer_channel_is_disabled(chan);
 126
 127                 /*
 128                  * lib_ring_buffer_is_finalized() contains a smp_rmb() ordering
 129                  * finalized load before offsets loads.
 130                  */
 131                 WARN_ON(atomic_long_read(&buf->active_readers) != 1);
 132 retry:
 133                 if (disabled)
 134                         return POLLERR;
 135
 136                 if (subbuf_trunc(lib_ring_buffer_get_offset(config, buf), chan)
 137                   - subbuf_trunc(lib_ring_buffer_get_consumed(config, buf), chan)
 138                   == 0) {
 139                         if (finalized)
 140                                 return POLLHUP;
 141                         else {
 142                                 /*
 143                                  * The memory barriers
 144                                  * __wait_event()/wake_up_interruptible() take
 145                                  * care of "raw_spin_is_locked" memory ordering.
 146                                  */
 147                                 if (raw_spin_is_locked(&buf->raw_tick_nohz_spinlock))
 148                                         goto retry;
 149                                 else
 150                                         return 0;
 151                         }
 152                 } else {
 153                         if (subbuf_trunc(lib_ring_buffer_get_offset(config, buf),
 154                                          chan)
 155                           - subbuf_trunc(lib_ring_buffer_get_consumed(config, buf),
 156                                          chan)
 157                           >= chan->backend.buf_size)
 158                                 return POLLPRI | POLLRDBAND;
 159                         else
 160                                 return POLLIN | POLLRDNORM;
 161                 }
 162         }
 163         return mask;
 164 }
 165 EXPORT_SYMBOL_GPL(lib_ring_buffer_poll);
 166
 167 /**
 168  *      vfs_lib_ring_buffer_poll - ring buffer poll file operation
 169  *      @filp: the file
 170  *      @wait: poll table
 171  *
 172  *      Poll implementation.
 173  */
 174 static
 175 unsigned int vfs_lib_ring_buffer_poll(struct file *filp, poll_table *wait)
 176 {
 177         struct lib_ring_buffer *buf = filp->private_data;
 178
 179         return lib_ring_buffer_poll(filp, wait, buf);
 180 }
 181
 182 long lib_ring_buffer_ioctl(struct file *filp, unsigned int cmd,
 183                 unsigned long arg, struct lib_ring_buffer *buf)
 184 {
 185         struct channel *chan = buf->backend.chan;
 186         const struct lib_ring_buffer_config *config = &chan->backend.config;
 187
 188         if (lib_ring_buffer_channel_is_disabled(chan))
 189                 return -EIO;
 190
 191         switch (cmd) {
 192         case RING_BUFFER_SNAPSHOT:
 193                 return lib_ring_buffer_snapshot(buf, &buf->cons_snapshot,
 194                                             &buf->prod_snapshot);
 195         case RING_BUFFER_SNAPSHOT_GET_CONSUMED:
 196                 return put_ulong(buf->cons_snapshot, arg);
 197         case RING_BUFFER_SNAPSHOT_GET_PRODUCED:
 198                 return put_ulong(buf->prod_snapshot, arg);
 199         case RING_BUFFER_GET_SUBBUF:
 200         {
 201                 unsigned long uconsume;
 202                 long ret;
 203
 204                 ret = get_user(uconsume, (unsigned long __user *) arg);
 205                 if (ret)
 206                         return ret; /* will return -EFAULT */
 207                 ret = lib_ring_buffer_get_subbuf(buf, uconsume);
 208                 if (!ret) {
 209                         /* Set file position to zero at each successful "get" */
 210                         filp->f_pos = 0;
 211                 }
 212                 return ret;
 213         }
 214         case RING_BUFFER_PUT_SUBBUF:
 215                 lib_ring_buffer_put_subbuf(buf);
 216                 return 0;
 217
 218         case RING_BUFFER_GET_NEXT_SUBBUF:
 219         {
 220                 long ret;
 221
 222                 ret = lib_ring_buffer_get_next_subbuf(buf);
 223                 if (!ret) {
 224                         /* Set file position to zero at each successful "get" */
 225                         filp->f_pos = 0;
 226                 }
 227                 return ret;
 228         }
 229         case RING_BUFFER_PUT_NEXT_SUBBUF:
 230                 lib_ring_buffer_put_next_subbuf(buf);
 231                 return 0;
 232         case RING_BUFFER_GET_SUBBUF_SIZE:
 233                 return put_ulong(lib_ring_buffer_get_read_data_size(config, buf),
 234                                  arg);
 235         case RING_BUFFER_GET_PADDED_SUBBUF_SIZE:
 236         {
 237                 unsigned long size;
 238
 239                 size = lib_ring_buffer_get_read_data_size(config, buf);
 240                 size = PAGE_ALIGN(size);
 241                 return put_ulong(size, arg);
 242         }
 243         case RING_BUFFER_GET_MAX_SUBBUF_SIZE:
 244                 return put_ulong(chan->backend.subbuf_size, arg);
 245         case RING_BUFFER_GET_MMAP_LEN:
 246         {
 247                 unsigned long mmap_buf_len;
 248
 249                 if (config->output != RING_BUFFER_MMAP)
 250                         return -EINVAL;
 251                 mmap_buf_len = chan->backend.buf_size;
 252                 if (chan->backend.extra_reader_sb)
 253                         mmap_buf_len += chan->backend.subbuf_size;
 254                 if (mmap_buf_len > INT_MAX)
 255                         return -EFBIG;
 256                 return put_ulong(mmap_buf_len, arg);
 257         }
 258         case RING_BUFFER_GET_MMAP_READ_OFFSET:
 259         {
 260                 unsigned long sb_bindex;
 261
 262                 if (config->output != RING_BUFFER_MMAP)
 263                         return -EINVAL;
 264                 sb_bindex = subbuffer_id_get_index(config,
 265                                                    buf->backend.buf_rsb.id);
 266                 return put_ulong(buf->backend.array[sb_bindex]->mmap_offset,
 267                                  arg);
 268         }
 269         case RING_BUFFER_FLUSH:
 270                 lib_ring_buffer_switch_remote(buf);
 271                 return 0;
 272         default:
 273                 return -ENOIOCTLCMD;
 274         }
 275 }
 276 EXPORT_SYMBOL_GPL(lib_ring_buffer_ioctl);
 277
 278 /**
 279  *      vfs_lib_ring_buffer_ioctl - control ring buffer reader synchronization
 280  *
 281  *      @filp: the file
 282  *      @cmd: the command
 283  *      @arg: command arg
 284  *
 285  *      This ioctl implements commands necessary for producer/consumer
 286  *      and flight recorder reader interaction :
 287  *      RING_BUFFER_GET_NEXT_SUBBUF
 288  *              Get the next sub-buffer that can be read. It never blocks.
 289  *      RING_BUFFER_PUT_NEXT_SUBBUF
 290  *              Release the currently read sub-buffer.
 291  *      RING_BUFFER_GET_SUBBUF_SIZE
 292  *              returns the size of the current sub-buffer.
 293  *      RING_BUFFER_GET_MAX_SUBBUF_SIZE
 294  *              returns the maximum size for sub-buffers.
 295  *      RING_BUFFER_GET_NUM_SUBBUF
 296  *              returns the number of reader-visible sub-buffers in the per cpu
 297  *              channel (for mmap).
 298  *      RING_BUFFER_GET_MMAP_READ_OFFSET
 299  *              returns the offset of the subbuffer belonging to the reader.
 300  *              Should only be used for mmap clients.
 301  */
 302 static
 303 long vfs_lib_ring_buffer_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 304 {
 305         struct lib_ring_buffer *buf = filp->private_data;
 306
 307         return lib_ring_buffer_ioctl(filp, cmd, arg, buf);
 308 }
 309
 310 #ifdef CONFIG_COMPAT
 311 long lib_ring_buffer_compat_ioctl(struct file *filp, unsigned int cmd,
 312                 unsigned long arg, struct lib_ring_buffer *buf)
 313 {
 314         struct channel *chan = buf->backend.chan;
 315         const struct lib_ring_buffer_config *config = &chan->backend.config;
 316
 317         if (lib_ring_buffer_channel_is_disabled(chan))
 318                 return -EIO;
 319
 320         switch (cmd) {
 321         case RING_BUFFER_COMPAT_SNAPSHOT:
 322                 return lib_ring_buffer_snapshot(buf, &buf->cons_snapshot,
 323                                                 &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         default:
 418                 return -ENOIOCTLCMD;
 419         }
 420 }
 421 EXPORT_SYMBOL_GPL(lib_ring_buffer_compat_ioctl);
 422
 423 static
 424 long vfs_lib_ring_buffer_compat_ioctl(struct file *filp, unsigned int cmd,
 425                                   unsigned long arg)
 426 {
 427         struct lib_ring_buffer *buf = filp->private_data;
 428
 429         return lib_ring_buffer_compat_ioctl(filp, cmd, arg, buf);
 430 }
 431 #endif
 432
 433 const struct file_operations lib_ring_buffer_file_operations = {
 434         .owner = THIS_MODULE,
 435         .open = vfs_lib_ring_buffer_open,
 436         .release = vfs_lib_ring_buffer_release,
 437         .poll = vfs_lib_ring_buffer_poll,
 438         .splice_read = vfs_lib_ring_buffer_splice_read,
 439         .mmap = vfs_lib_ring_buffer_mmap,
 440         .unlocked_ioctl = vfs_lib_ring_buffer_ioctl,
 441         .llseek = vfs_lib_ring_buffer_no_llseek,
 442 #ifdef CONFIG_COMPAT
 443         .compat_ioctl = vfs_lib_ring_buffer_compat_ioctl,
 444 #endif
 445 };
 446 EXPORT_SYMBOL_GPL(lib_ring_buffer_file_operations);
 447
 448 MODULE_LICENSE("GPL and additional rights");
 449 MODULE_AUTHOR("Mathieu Desnoyers");
 450 MODULE_DESCRIPTION("Ring Buffer Library VFS");