libringbuffer/ring_buffer_abi.c

   1 /*
   2  * ring_buffer_abi.c
   3  *
   4  * Copyright (C) 2009-2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  *
   6  * Ring Buffer VFS file operations.
   7  *
   8  * Dual LGPL v2.1/GPL v2 license.
   9  */
  10
  11 #include "backend.h"
  12 #include "frontend.h"
  13 #include <ust/ring-buffer-abi.h>
  14
  15 static int put_ulong(unsigned long val, unsigned long arg)
  16 {
  17         return put_user(val, (unsigned long __user *)arg);
  18 }
  19
  20 #ifdef CONFIG_COMPAT
  21 static int compat_put_ulong(compat_ulong_t val, unsigned long arg)
  22 {
  23         return put_user(val, (compat_ulong_t __user *)compat_ptr(arg));
  24 }
  25 #endif
  26
  27 /**
  28  *      lib_ring_buffer_open - ring buffer open file operation
  29  *      @inode: opened inode
  30  *      @file: opened file
  31  *
  32  *      Open implementation. Makes sure only one open instance of a buffer is
  33  *      done at a given moment.
  34  */
  35 int lib_ring_buffer_open(struct inode *inode, struct file *file)
  36 {
  37         struct lib_ring_buffer *buf = inode->i_private;
  38         int ret;
  39
  40         ret = lib_ring_buffer_open_read(buf);
  41         if (ret)
  42                 return ret;
  43
  44         file->private_data = buf;
  45         ret = nonseekable_open(inode, file);
  46         if (ret)
  47                 goto release_read;
  48         return 0;
  49
  50 release_read:
  51         lib_ring_buffer_release_read(buf);
  52         return ret;
  53 }
  54
  55 /**
  56  *      lib_ring_buffer_release - ring buffer release file operation
  57  *      @inode: opened inode
  58  *      @file: opened file
  59  *
  60  *      Release implementation.
  61  */
  62 int lib_ring_buffer_release(struct inode *inode, struct file *file)
  63 {
  64         struct lib_ring_buffer *buf = file->private_data;
  65
  66         lib_ring_buffer_release_read(buf);
  67
  68         return 0;
  69 }
  70
  71 /**
  72  *      lib_ring_buffer_poll - ring buffer poll file operation
  73  *      @filp: the file
  74  *      @wait: poll table
  75  *
  76  *      Poll implementation.
  77  */
  78 unsigned int lib_ring_buffer_poll(struct file *filp, poll_table *wait)
  79 {
  80         unsigned int mask = 0;
  81         struct lib_ring_buffer *buf = filp->private_data;
  82         struct channel *chan = buf->backend.chan;
  83         const struct lib_ring_buffer_config *config = chan->backend.config;
  84         int finalized, disabled;
  85
  86         if (filp->f_mode & FMODE_READ) {
  87                 poll_wait_set_exclusive(wait);
  88                 poll_wait(filp, &buf->read_wait, wait);
  89
  90                 finalized = lib_ring_buffer_is_finalized(config, buf);
  91                 disabled = lib_ring_buffer_channel_is_disabled(chan);
  92
  93                 /*
  94                  * lib_ring_buffer_is_finalized() contains a smp_rmb() ordering
  95                  * finalized load before offsets loads.
  96                  */
  97                 WARN_ON(atomic_long_read(&buf->active_readers) != 1);
  98 retry:
  99                 if (disabled)
 100                         return POLLERR;
 101
 102                 if (subbuf_trunc(lib_ring_buffer_get_offset(config, buf), chan)
 103                   - subbuf_trunc(lib_ring_buffer_get_consumed(config, buf), chan)
 104                   == 0) {
 105                         if (finalized)
 106                                 return POLLHUP;
 107                         else {
 108                                 /*
 109                                  * The memory barriers
 110                                  * __wait_event()/wake_up_interruptible() take
 111                                  * care of "raw_spin_is_locked" memory ordering.
 112                                  */
 113                                 if (raw_spin_is_locked(&buf->raw_tick_nohz_spinlock))
 114                                         goto retry;
 115                                 else
 116                                         return 0;
 117                         }
 118                 } else {
 119                         if (subbuf_trunc(lib_ring_buffer_get_offset(config, buf),
 120                                          chan)
 121                           - subbuf_trunc(lib_ring_buffer_get_consumed(config, buf),
 122                                          chan)
 123                           >= chan->backend.buf_size)
 124                                 return POLLPRI | POLLRDBAND;
 125                         else
 126                                 return POLLIN | POLLRDNORM;
 127                 }
 128         }
 129         return mask;
 130 }
 131
 132 /**
 133  *      lib_ring_buffer_ioctl - control ring buffer reader synchronization
 134  *
 135  *      @filp: the file
 136  *      @cmd: the command
 137  *      @arg: command arg
 138  *
 139  *      This ioctl implements commands necessary for producer/consumer
 140  *      and flight recorder reader interaction :
 141  *      RING_BUFFER_GET_NEXT_SUBBUF
 142  *              Get the next sub-buffer that can be read. It never blocks.
 143  *      RING_BUFFER_PUT_NEXT_SUBBUF
 144  *              Release the currently read sub-buffer.
 145  *      RING_BUFFER_GET_SUBBUF_SIZE
 146  *              returns the size of the current sub-buffer.
 147  *      RING_BUFFER_GET_MAX_SUBBUF_SIZE
 148  *              returns the maximum size for sub-buffers.
 149  *      RING_BUFFER_GET_NUM_SUBBUF
 150  *              returns the number of reader-visible sub-buffers in the per cpu
 151  *              channel (for mmap).
 152  *      RING_BUFFER_GET_MMAP_READ_OFFSET
 153  *              returns the offset of the subbuffer belonging to the reader.
 154  *              Should only be used for mmap clients.
 155  */
 156 long lib_ring_buffer_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 157 {
 158         struct lib_ring_buffer *buf = filp->private_data;
 159         struct channel *chan = buf->backend.chan;
 160         const struct lib_ring_buffer_config *config = chan->backend.config;
 161
 162         if (lib_ring_buffer_channel_is_disabled(chan))
 163                 return -EIO;
 164
 165         switch (cmd) {
 166         case RING_BUFFER_SNAPSHOT:
 167                 return lib_ring_buffer_snapshot(buf, &buf->cons_snapshot,
 168                                             &buf->prod_snapshot);
 169         case RING_BUFFER_SNAPSHOT_GET_CONSUMED:
 170                 return put_ulong(buf->cons_snapshot, arg);
 171         case RING_BUFFER_SNAPSHOT_GET_PRODUCED:
 172                 return put_ulong(buf->prod_snapshot, arg);
 173         case RING_BUFFER_GET_SUBBUF:
 174         {
 175                 unsigned long uconsume;
 176                 long ret;
 177
 178                 ret = get_user(uconsume, (unsigned long __user *) arg);
 179                 if (ret)
 180                         return ret; /* will return -EFAULT */
 181                 ret = lib_ring_buffer_get_subbuf(buf, uconsume);
 182                 if (!ret) {
 183                         /* Set file position to zero at each successful "get" */
 184                         filp->f_pos = 0;
 185                 }
 186                 return ret;
 187         }
 188         case RING_BUFFER_PUT_SUBBUF:
 189                 lib_ring_buffer_put_subbuf(buf);
 190                 return 0;
 191
 192         case RING_BUFFER_GET_NEXT_SUBBUF:
 193         {
 194                 long ret;
 195
 196                 ret = lib_ring_buffer_get_next_subbuf(buf);
 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_NEXT_SUBBUF:
 204                 lib_ring_buffer_put_next_subbuf(buf);
 205                 return 0;
 206         case RING_BUFFER_GET_SUBBUF_SIZE:
 207                 return put_ulong(lib_ring_buffer_get_read_data_size(config, buf),
 208                                  arg);
 209         case RING_BUFFER_GET_PADDED_SUBBUF_SIZE:
 210         {
 211                 unsigned long size;
 212
 213                 size = lib_ring_buffer_get_read_data_size(config, buf);
 214                 size = PAGE_ALIGN(size);
 215                 return put_ulong(size, arg);
 216         }
 217         case RING_BUFFER_GET_MAX_SUBBUF_SIZE:
 218                 return put_ulong(chan->backend.subbuf_size, arg);
 219         case RING_BUFFER_GET_MMAP_LEN:
 220         {
 221                 unsigned long mmap_buf_len;
 222
 223                 if (config->output != RING_BUFFER_MMAP)
 224                         return -EINVAL;
 225                 mmap_buf_len = chan->backend.buf_size;
 226                 if (chan->backend.extra_reader_sb)
 227                         mmap_buf_len += chan->backend.subbuf_size;
 228                 if (mmap_buf_len > INT_MAX)
 229                         return -EFBIG;
 230                 return put_ulong(mmap_buf_len, arg);
 231         }
 232         case RING_BUFFER_GET_MMAP_READ_OFFSET:
 233         {
 234                 unsigned long sb_bindex;
 235
 236                 if (config->output != RING_BUFFER_MMAP)
 237                         return -EINVAL;
 238                 sb_bindex = subbuffer_id_get_index(config,
 239                                                    buf->backend.buf_rsb.id);
 240                 return put_ulong(buf->backend.array[sb_bindex]->mmap_offset,
 241                                  arg);
 242         }
 243         case RING_BUFFER_FLUSH:
 244                 lib_ring_buffer_switch_slow(buf, SWITCH_ACTIVE, handle);
 245                 return 0;
 246         default:
 247                 return -ENOIOCTLCMD;
 248         }
 249 }
 250
 251 #ifdef CONFIG_COMPAT
 252 long lib_ring_buffer_compat_ioctl(struct file *filp, unsigned int cmd,
 253                                   unsigned long arg)
 254 {
 255         struct lib_ring_buffer *buf = filp->private_data;
 256         struct channel *chan = buf->backend.chan;
 257         const struct lib_ring_buffer_config *config = chan->backend.config;
 258
 259         if (lib_ring_buffer_channel_is_disabled(chan))
 260                 return -EIO;
 261
 262         switch (cmd) {
 263         case RING_BUFFER_SNAPSHOT:
 264                 return lib_ring_buffer_snapshot(buf, &buf->cons_snapshot,
 265                                                 &buf->prod_snapshot);
 266         case RING_BUFFER_SNAPSHOT_GET_CONSUMED:
 267                 return compat_put_ulong(buf->cons_snapshot, arg);
 268         case RING_BUFFER_SNAPSHOT_GET_PRODUCED:
 269                 return compat_put_ulong(buf->prod_snapshot, arg);
 270         case RING_BUFFER_GET_SUBBUF:
 271         {
 272                 __u32 uconsume;
 273                 unsigned long consume;
 274                 long ret;
 275
 276                 ret = get_user(uconsume, (__u32 __user *) arg);
 277                 if (ret)
 278                         return ret; /* will return -EFAULT */
 279                 consume = buf->cons_snapshot;
 280                 consume &= ~0xFFFFFFFFL;
 281                 consume |= uconsume;
 282                 ret = lib_ring_buffer_get_subbuf(buf, consume);
 283                 if (!ret) {
 284                         /* Set file position to zero at each successful "get" */
 285                         filp->f_pos = 0;
 286                 }
 287                 return ret;
 288         }
 289         case RING_BUFFER_PUT_SUBBUF:
 290                 lib_ring_buffer_put_subbuf(buf);
 291                 return 0;
 292
 293         case RING_BUFFER_GET_NEXT_SUBBUF:
 294         {
 295                 long ret;
 296
 297                 ret = lib_ring_buffer_get_next_subbuf(buf);
 298                 if (!ret) {
 299                         /* Set file position to zero at each successful "get" */
 300                         filp->f_pos = 0;
 301                 }
 302                 return ret;
 303         }
 304         case RING_BUFFER_PUT_NEXT_SUBBUF:
 305                 lib_ring_buffer_put_next_subbuf(buf);
 306                 return 0;
 307         case RING_BUFFER_GET_SUBBUF_SIZE:
 308         {
 309                 unsigned long data_size;
 310
 311                 data_size = lib_ring_buffer_get_read_data_size(config, buf);
 312                 if (data_size > UINT_MAX)
 313                         return -EFBIG;
 314                 return put_ulong(data_size, arg);
 315         }
 316         case RING_BUFFER_GET_PADDED_SUBBUF_SIZE:
 317         {
 318                 unsigned long size;
 319
 320                 size = lib_ring_buffer_get_read_data_size(config, buf);
 321                 size = PAGE_ALIGN(size);
 322                 if (size > UINT_MAX)
 323                         return -EFBIG;
 324                 return put_ulong(size, arg);
 325         }
 326         case RING_BUFFER_GET_MAX_SUBBUF_SIZE:
 327                 if (chan->backend.subbuf_size > UINT_MAX)
 328                         return -EFBIG;
 329                 return put_ulong(chan->backend.subbuf_size, arg);
 330         case RING_BUFFER_GET_MMAP_LEN:
 331         {
 332                 unsigned long mmap_buf_len;
 333
 334                 if (config->output != RING_BUFFER_MMAP)
 335                         return -EINVAL;
 336                 mmap_buf_len = chan->backend.buf_size;
 337                 if (chan->backend.extra_reader_sb)
 338                         mmap_buf_len += chan->backend.subbuf_size;
 339                 if (mmap_buf_len > UINT_MAX)
 340                         return -EFBIG;
 341                 return put_ulong(mmap_buf_len, arg);
 342         }
 343         case RING_BUFFER_GET_MMAP_READ_OFFSET:
 344         {
 345                 unsigned long sb_bindex, read_offset;
 346
 347                 if (config->output != RING_BUFFER_MMAP)
 348                         return -EINVAL;
 349                 sb_bindex = subbuffer_id_get_index(config,
 350                                                    buf->backend.buf_rsb.id);
 351                 read_offset = buf->backend.array[sb_bindex]->mmap_offset;
 352                 if (read_offset > UINT_MAX)
 353                         return -EINVAL;
 354                 return put_ulong(read_offset, arg);
 355         }
 356         case RING_BUFFER_FLUSH:
 357                 lib_ring_buffer_switch_slow(buf, SWITCH_ACTIVE, handle);
 358                 return 0;
 359         default:
 360                 return -ENOIOCTLCMD;
 361         }
 362 }
 363 #endif
 364
 365 const struct file_operations lib_ring_buffer_file_operations = {
 366         .open = lib_ring_buffer_open,
 367         .release = lib_ring_buffer_release,
 368         .poll = lib_ring_buffer_poll,
 369         .splice_read = lib_ring_buffer_splice_read,
 370         .mmap = lib_ring_buffer_mmap,
 371         .unlocked_ioctl = lib_ring_buffer_ioctl,
 372         .llseek = lib_ring_buffer_no_llseek,
 373 #ifdef CONFIG_COMPAT
 374         .compat_ioctl = lib_ring_buffer_compat_ioctl,
 375 #endif
 376 };