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  *      lib_ring_buffer_open - ring buffer open file operation
  46  *      @inode: opened inode
  47  *      @file: opened file
  48  *
  49  *      Open implementation. Makes sure only one open instance of a buffer is
  50  *      done at a given moment.
  51  */
  52 int lib_ring_buffer_open(struct inode *inode, struct file *file)
  53 {
  54         struct lib_ring_buffer *buf = inode->i_private;
  55         int ret;
  56
  57         if (!buf)
  58                 return -EINVAL;
  59
  60         ret = lib_ring_buffer_open_read(buf);
  61         if (ret)
  62                 return ret;
  63
  64         file->private_data = buf;
  65         ret = nonseekable_open(inode, file);
  66         if (ret)
  67                 goto release_read;
  68         return 0;
  69
  70 release_read:
  71         lib_ring_buffer_release_read(buf);
  72         return ret;
  73 }
  74
  75 /**
  76  *      lib_ring_buffer_release - ring buffer release file operation
  77  *      @inode: opened inode
  78  *      @file: opened file
  79  *
  80  *      Release implementation.
  81  */
  82 int lib_ring_buffer_release(struct inode *inode, struct file *file)
  83 {
  84         struct lib_ring_buffer *buf = file->private_data;
  85
  86         lib_ring_buffer_release_read(buf);
  87
  88         return 0;
  89 }
  90
  91 /**
  92  *      lib_ring_buffer_poll - ring buffer poll file operation
  93  *      @filp: the file
  94  *      @wait: poll table
  95  *
  96  *      Poll implementation.
  97  */
  98 unsigned int lib_ring_buffer_poll(struct file *filp, poll_table *wait)
  99 {
 100         unsigned int mask = 0;
 101         struct lib_ring_buffer *buf = filp->private_data;
 102         struct channel *chan = buf->backend.chan;
 103         const struct lib_ring_buffer_config *config = &chan->backend.config;
 104         int finalized, disabled;
 105
 106         if (filp->f_mode & FMODE_READ) {
 107                 poll_wait_set_exclusive(wait);
 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
 152 /**
 153  *      lib_ring_buffer_ioctl - control ring buffer reader synchronization
 154  *
 155  *      @filp: the file
 156  *      @cmd: the command
 157  *      @arg: command arg
 158  *
 159  *      This ioctl implements commands necessary for producer/consumer
 160  *      and flight recorder reader interaction :
 161  *      RING_BUFFER_GET_NEXT_SUBBUF
 162  *              Get the next sub-buffer that can be read. It never blocks.
 163  *      RING_BUFFER_PUT_NEXT_SUBBUF
 164  *              Release the currently read sub-buffer.
 165  *      RING_BUFFER_GET_SUBBUF_SIZE
 166  *              returns the size of the current sub-buffer.
 167  *      RING_BUFFER_GET_MAX_SUBBUF_SIZE
 168  *              returns the maximum size for sub-buffers.
 169  *      RING_BUFFER_GET_NUM_SUBBUF
 170  *              returns the number of reader-visible sub-buffers in the per cpu
 171  *              channel (for mmap).
 172  *      RING_BUFFER_GET_MMAP_READ_OFFSET
 173  *              returns the offset of the subbuffer belonging to the reader.
 174  *              Should only be used for mmap clients.
 175  */
 176 long lib_ring_buffer_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 177 {
 178         struct lib_ring_buffer *buf = filp->private_data;
 179         struct channel *chan = buf->backend.chan;
 180         const struct lib_ring_buffer_config *config = &chan->backend.config;
 181
 182         if (lib_ring_buffer_channel_is_disabled(chan))
 183                 return -EIO;
 184
 185         switch (cmd) {
 186         case RING_BUFFER_SNAPSHOT:
 187                 return lib_ring_buffer_snapshot(buf, &buf->cons_snapshot,
 188                                             &buf->prod_snapshot);
 189         case RING_BUFFER_SNAPSHOT_GET_CONSUMED:
 190                 return put_ulong(buf->cons_snapshot, arg);
 191         case RING_BUFFER_SNAPSHOT_GET_PRODUCED:
 192                 return put_ulong(buf->prod_snapshot, arg);
 193         case RING_BUFFER_GET_SUBBUF:
 194         {
 195                 unsigned long uconsume;
 196                 long ret;
 197
 198                 ret = get_user(uconsume, (unsigned long __user *) arg);
 199                 if (ret)
 200                         return ret; /* will return -EFAULT */
 201                 ret = lib_ring_buffer_get_subbuf(buf, uconsume);
 202                 if (!ret) {
 203                         /* Set file position to zero at each successful "get" */
 204                         filp->f_pos = 0;
 205                 }
 206                 return ret;
 207         }
 208         case RING_BUFFER_PUT_SUBBUF:
 209                 lib_ring_buffer_put_subbuf(buf);
 210                 return 0;
 211
 212         case RING_BUFFER_GET_NEXT_SUBBUF:
 213         {
 214                 long ret;
 215
 216                 ret = lib_ring_buffer_get_next_subbuf(buf);
 217                 if (!ret) {
 218                         /* Set file position to zero at each successful "get" */
 219                         filp->f_pos = 0;
 220                 }
 221                 return ret;
 222         }
 223         case RING_BUFFER_PUT_NEXT_SUBBUF:
 224                 lib_ring_buffer_put_next_subbuf(buf);
 225                 return 0;
 226         case RING_BUFFER_GET_SUBBUF_SIZE:
 227                 return put_ulong(lib_ring_buffer_get_read_data_size(config, buf),
 228                                  arg);
 229         case RING_BUFFER_GET_PADDED_SUBBUF_SIZE:
 230         {
 231                 unsigned long size;
 232
 233                 size = lib_ring_buffer_get_read_data_size(config, buf);
 234                 size = PAGE_ALIGN(size);
 235                 return put_ulong(size, arg);
 236         }
 237         case RING_BUFFER_GET_MAX_SUBBUF_SIZE:
 238                 return put_ulong(chan->backend.subbuf_size, arg);
 239         case RING_BUFFER_GET_MMAP_LEN:
 240         {
 241                 unsigned long mmap_buf_len;
 242
 243                 if (config->output != RING_BUFFER_MMAP)
 244                         return -EINVAL;
 245                 mmap_buf_len = chan->backend.buf_size;
 246                 if (chan->backend.extra_reader_sb)
 247                         mmap_buf_len += chan->backend.subbuf_size;
 248                 if (mmap_buf_len > INT_MAX)
 249                         return -EFBIG;
 250                 return put_ulong(mmap_buf_len, arg);
 251         }
 252         case RING_BUFFER_GET_MMAP_READ_OFFSET:
 253         {
 254                 unsigned long sb_bindex;
 255
 256                 if (config->output != RING_BUFFER_MMAP)
 257                         return -EINVAL;
 258                 sb_bindex = subbuffer_id_get_index(config,
 259                                                    buf->backend.buf_rsb.id);
 260                 return put_ulong(buf->backend.array[sb_bindex]->mmap_offset,
 261                                  arg);
 262         }
 263         case RING_BUFFER_FLUSH:
 264                 lib_ring_buffer_switch_slow(buf, SWITCH_ACTIVE);
 265                 return 0;
 266         default:
 267                 return -ENOIOCTLCMD;
 268         }
 269 }
 270
 271 #ifdef CONFIG_COMPAT
 272 long lib_ring_buffer_compat_ioctl(struct file *filp, unsigned int cmd,
 273                                   unsigned long arg)
 274 {
 275         struct lib_ring_buffer *buf = filp->private_data;
 276         struct channel *chan = buf->backend.chan;
 277         const struct lib_ring_buffer_config *config = &chan->backend.config;
 278
 279         if (lib_ring_buffer_channel_is_disabled(chan))
 280                 return -EIO;
 281
 282         switch (cmd) {
 283         case RING_BUFFER_COMPAT_SNAPSHOT:
 284                 return lib_ring_buffer_snapshot(buf, &buf->cons_snapshot,
 285                                                 &buf->prod_snapshot);
 286         case RING_BUFFER_COMPAT_SNAPSHOT_GET_CONSUMED:
 287                 return compat_put_ulong(buf->cons_snapshot, arg);
 288         case RING_BUFFER_COMPAT_SNAPSHOT_GET_PRODUCED:
 289                 return compat_put_ulong(buf->prod_snapshot, arg);
 290         case RING_BUFFER_COMPAT_GET_SUBBUF:
 291         {
 292                 __u32 uconsume;
 293                 unsigned long consume;
 294                 long ret;
 295
 296                 ret = get_user(uconsume, (__u32 __user *) arg);
 297                 if (ret)
 298                         return ret; /* will return -EFAULT */
 299                 consume = buf->cons_snapshot;
 300                 consume &= ~0xFFFFFFFFL;
 301                 consume |= uconsume;
 302                 ret = lib_ring_buffer_get_subbuf(buf, consume);
 303                 if (!ret) {
 304                         /* Set file position to zero at each successful "get" */
 305                         filp->f_pos = 0;
 306                 }
 307                 return ret;
 308         }
 309         case RING_BUFFER_COMPAT_PUT_SUBBUF:
 310                 lib_ring_buffer_put_subbuf(buf);
 311                 return 0;
 312
 313         case RING_BUFFER_COMPAT_GET_NEXT_SUBBUF:
 314         {
 315                 long ret;
 316
 317                 ret = lib_ring_buffer_get_next_subbuf(buf);
 318                 if (!ret) {
 319                         /* Set file position to zero at each successful "get" */
 320                         filp->f_pos = 0;
 321                 }
 322                 return ret;
 323         }
 324         case RING_BUFFER_COMPAT_PUT_NEXT_SUBBUF:
 325                 lib_ring_buffer_put_next_subbuf(buf);
 326                 return 0;
 327         case RING_BUFFER_COMPAT_GET_SUBBUF_SIZE:
 328         {
 329                 unsigned long data_size;
 330
 331                 data_size = lib_ring_buffer_get_read_data_size(config, buf);
 332                 if (data_size > UINT_MAX)
 333                         return -EFBIG;
 334                 return compat_put_ulong(data_size, arg);
 335         }
 336         case RING_BUFFER_COMPAT_GET_PADDED_SUBBUF_SIZE:
 337         {
 338                 unsigned long size;
 339
 340                 size = lib_ring_buffer_get_read_data_size(config, buf);
 341                 size = PAGE_ALIGN(size);
 342                 if (size > UINT_MAX)
 343                         return -EFBIG;
 344                 return compat_put_ulong(size, arg);
 345         }
 346         case RING_BUFFER_COMPAT_GET_MAX_SUBBUF_SIZE:
 347                 if (chan->backend.subbuf_size > UINT_MAX)
 348                         return -EFBIG;
 349                 return compat_put_ulong(chan->backend.subbuf_size, arg);
 350         case RING_BUFFER_COMPAT_GET_MMAP_LEN:
 351         {
 352                 unsigned long mmap_buf_len;
 353
 354                 if (config->output != RING_BUFFER_MMAP)
 355                         return -EINVAL;
 356                 mmap_buf_len = chan->backend.buf_size;
 357                 if (chan->backend.extra_reader_sb)
 358                         mmap_buf_len += chan->backend.subbuf_size;
 359                 if (mmap_buf_len > UINT_MAX)
 360                         return -EFBIG;
 361                 return compat_put_ulong(mmap_buf_len, arg);
 362         }
 363         case RING_BUFFER_COMPAT_GET_MMAP_READ_OFFSET:
 364         {
 365                 unsigned long sb_bindex, read_offset;
 366
 367                 if (config->output != RING_BUFFER_MMAP)
 368                         return -EINVAL;
 369                 sb_bindex = subbuffer_id_get_index(config,
 370                                                    buf->backend.buf_rsb.id);
 371                 read_offset = buf->backend.array[sb_bindex]->mmap_offset;
 372                 if (read_offset > UINT_MAX)
 373                         return -EINVAL;
 374                 return compat_put_ulong(read_offset, arg);
 375         }
 376         case RING_BUFFER_COMPAT_FLUSH:
 377                 lib_ring_buffer_switch_slow(buf, SWITCH_ACTIVE);
 378                 return 0;
 379         default:
 380                 return -ENOIOCTLCMD;
 381         }
 382 }
 383 #endif
 384
 385 const struct file_operations lib_ring_buffer_file_operations = {
 386         .owner = THIS_MODULE,
 387         .open = lib_ring_buffer_open,
 388         .release = lib_ring_buffer_release,
 389         .poll = lib_ring_buffer_poll,
 390         .splice_read = lib_ring_buffer_splice_read,
 391         .mmap = lib_ring_buffer_mmap,
 392         .unlocked_ioctl = lib_ring_buffer_ioctl,
 393         .llseek = lib_ring_buffer_no_llseek,
 394 #ifdef CONFIG_COMPAT
 395         .compat_ioctl = lib_ring_buffer_compat_ioctl,
 396 #endif
 397 };
 398 EXPORT_SYMBOL_GPL(lib_ring_buffer_file_operations);
 399
 400 MODULE_LICENSE("GPL and additional rights");
 401 MODULE_AUTHOR("Mathieu Desnoyers");
 402 MODULE_DESCRIPTION("Ring Buffer Library VFS");