drivers/staging/android/logger.c

   1 /*
   2  * drivers/misc/logger.c
   3  *
   4  * A Logging Subsystem
   5  *
   6  * Copyright (C) 2007-2008 Google, Inc.
   7  *
   8  * Robert Love <rlove@google.com>
   9  *
  10  * This software is licensed under the terms of the GNU General Public
  11  * License version 2, as published by the Free Software Foundation, and
  12  * may be copied, distributed, and modified under those terms.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  * GNU General Public License for more details.
  18  */
  19
  20 #define pr_fmt(fmt) "logger: " fmt
  21
  22 #include <linux/sched.h>
  23 #include <linux/module.h>
  24 #include <linux/fs.h>
  25 #include <linux/miscdevice.h>
  26 #include <linux/uaccess.h>
  27 #include <linux/poll.h>
  28 #include <linux/slab.h>
  29 #include <linux/time.h>
  30 #include <linux/vmalloc.h>
  31 #include <linux/aio.h>
  32 #include "logger.h"
  33
  34 #include <asm/ioctls.h>
  35
  36 /**
  37  * struct logger_log - represents a specific log, such as 'main' or 'radio'
  38  * @buffer:     The actual ring buffer
  39  * @misc:       The "misc" device representing the log
  40  * @wq:         The wait queue for @readers
  41  * @readers:    This log's readers
  42  * @mutex:      The mutex that protects the @buffer
  43  * @w_off:      The current write head offset
  44  * @head:       The head, or location that readers start reading at.
  45  * @size:       The size of the log
  46  * @logs:       The list of log channels
  47  *
  48  * This structure lives from module insertion until module removal, so it does
  49  * not need additional reference counting. The structure is protected by the
  50  * mutex 'mutex'.
  51  */
  52 struct logger_log {
  53         unsigned char           *buffer;
  54         struct miscdevice       misc;
  55         wait_queue_head_t       wq;
  56         struct list_head        readers;
  57         struct mutex            mutex;
  58         size_t                  w_off;
  59         size_t                  head;
  60         size_t                  size;
  61         struct list_head        logs;
  62 };
  63
  64 static LIST_HEAD(log_list);
  65
  66 /**
  67  * struct logger_reader - a logging device open for reading
  68  * @log:        The associated log
  69  * @list:       The associated entry in @logger_log's list
  70  * @r_off:      The current read head offset.
  71  * @r_all:      Reader can read all entries
  72  * @r_ver:      Reader ABI version
  73  *
  74  * This object lives from open to release, so we don't need additional
  75  * reference counting. The structure is protected by log->mutex.
  76  */
  77 struct logger_reader {
  78         struct logger_log       *log;
  79         struct list_head        list;
  80         size_t                  r_off;
  81         bool                    r_all;
  82         int                     r_ver;
  83 };
  84
  85 /* logger_offset - returns index 'n' into the log via (optimized) modulus */
  86 static size_t logger_offset(struct logger_log *log, size_t n)
  87 {
  88         return n & (log->size - 1);
  89 }
  90
  91 /*
  92  * file_get_log - Given a file structure, return the associated log
  93  *
  94  * This isn't aesthetic. We have several goals:
  95  *
  96  *      1) Need to quickly obtain the associated log during an I/O operation
  97  *      2) Readers need to maintain state (logger_reader)
  98  *      3) Writers need to be very fast (open() should be a near no-op)
  99  *
 100  * In the reader case, we can trivially go file->logger_reader->logger_log.
 101  * For a writer, we don't want to maintain a logger_reader, so we just go
 102  * file->logger_log. Thus what file->private_data points at depends on whether
 103  * or not the file was opened for reading. This function hides that dirtiness.
 104  */
 105 static inline struct logger_log *file_get_log(struct file *file)
 106 {
 107         if (file->f_mode & FMODE_READ) {
 108                 struct logger_reader *reader = file->private_data;
 109
 110                 return reader->log;
 111         }
 112         return file->private_data;
 113 }
 114
 115 /*
 116  * get_entry_header - returns a pointer to the logger_entry header within
 117  * 'log' starting at offset 'off'. A temporary logger_entry 'scratch' must
 118  * be provided. Typically the return value will be a pointer within
 119  * 'logger->buf'.  However, a pointer to 'scratch' may be returned if
 120  * the log entry spans the end and beginning of the circular buffer.
 121  */
 122 static struct logger_entry *get_entry_header(struct logger_log *log,
 123                                              size_t off,
 124                                              struct logger_entry *scratch)
 125 {
 126         size_t len = min(sizeof(struct logger_entry), log->size - off);
 127
 128         if (len != sizeof(struct logger_entry)) {
 129                 memcpy(((void *)scratch), log->buffer + off, len);
 130                 memcpy(((void *)scratch) + len, log->buffer,
 131                        sizeof(struct logger_entry) - len);
 132                 return scratch;
 133         }
 134
 135         return (struct logger_entry *) (log->buffer + off);
 136 }
 137
 138 /*
 139  * get_entry_msg_len - Grabs the length of the message of the entry
 140  * starting from from 'off'.
 141  *
 142  * An entry length is 2 bytes (16 bits) in host endian order.
 143  * In the log, the length does not include the size of the log entry structure.
 144  * This function returns the size including the log entry structure.
 145  *
 146  * Caller needs to hold log->mutex.
 147  */
 148 static __u32 get_entry_msg_len(struct logger_log *log, size_t off)
 149 {
 150         struct logger_entry scratch;
 151         struct logger_entry *entry;
 152
 153         entry = get_entry_header(log, off, &scratch);
 154         return entry->len;
 155 }
 156
 157 static size_t get_user_hdr_len(int ver)
 158 {
 159         if (ver < 2)
 160                 return sizeof(struct user_logger_entry_compat);
 161         return sizeof(struct logger_entry);
 162 }
 163
 164 static ssize_t copy_header_to_user(int ver, struct logger_entry *entry,
 165                                    char __user *buf)
 166 {
 167         void *hdr;
 168         size_t hdr_len;
 169         struct user_logger_entry_compat v1;
 170
 171         if (ver < 2) {
 172                 v1.len      = entry->len;
 173                 v1.__pad    = 0;
 174                 v1.pid      = entry->pid;
 175                 v1.tid      = entry->tid;
 176                 v1.sec      = entry->sec;
 177                 v1.nsec     = entry->nsec;
 178                 hdr         = &v1;
 179                 hdr_len     = sizeof(struct user_logger_entry_compat);
 180         } else {
 181                 hdr         = entry;
 182                 hdr_len     = sizeof(struct logger_entry);
 183         }
 184
 185         return copy_to_user(buf, hdr, hdr_len);
 186 }
 187
 188 /*
 189  * do_read_log_to_user - reads exactly 'count' bytes from 'log' into the
 190  * user-space buffer 'buf'. Returns 'count' on success.
 191  *
 192  * Caller must hold log->mutex.
 193  */
 194 static ssize_t do_read_log_to_user(struct logger_log *log,
 195                                    struct logger_reader *reader,
 196                                    char __user *buf,
 197                                    size_t count)
 198 {
 199         struct logger_entry scratch;
 200         struct logger_entry *entry;
 201         size_t len;
 202         size_t msg_start;
 203
 204         /*
 205          * First, copy the header to userspace, using the version of
 206          * the header requested
 207          */
 208         entry = get_entry_header(log, reader->r_off, &scratch);
 209         if (copy_header_to_user(reader->r_ver, entry, buf))
 210                 return -EFAULT;
 211
 212         count -= get_user_hdr_len(reader->r_ver);
 213         buf += get_user_hdr_len(reader->r_ver);
 214         msg_start = logger_offset(log,
 215                                   reader->r_off + sizeof(struct logger_entry));
 216
 217         /*
 218          * We read from the msg in two disjoint operations. First, we read from
 219          * the current msg head offset up to 'count' bytes or to the end of
 220          * the log, whichever comes first.
 221          */
 222         len = min(count, log->size - msg_start);
 223         if (copy_to_user(buf, log->buffer + msg_start, len))
 224                 return -EFAULT;
 225
 226         /*
 227          * Second, we read any remaining bytes, starting back at the head of
 228          * the log.
 229          */
 230         if (count != len)
 231                 if (copy_to_user(buf + len, log->buffer, count - len))
 232                         return -EFAULT;
 233
 234         reader->r_off = logger_offset(log, reader->r_off +
 235                 sizeof(struct logger_entry) + count);
 236
 237         return count + get_user_hdr_len(reader->r_ver);
 238 }
 239
 240 /*
 241  * get_next_entry_by_uid - Starting at 'off', returns an offset into
 242  * 'log->buffer' which contains the first entry readable by 'euid'
 243  */
 244 static size_t get_next_entry_by_uid(struct logger_log *log,
 245                                     size_t off, kuid_t euid)
 246 {
 247         while (off != log->w_off) {
 248                 struct logger_entry *entry;
 249                 struct logger_entry scratch;
 250                 size_t next_len;
 251
 252                 entry = get_entry_header(log, off, &scratch);
 253
 254                 if (uid_eq(entry->euid, euid))
 255                         return off;
 256
 257                 next_len = sizeof(struct logger_entry) + entry->len;
 258                 off = logger_offset(log, off + next_len);
 259         }
 260
 261         return off;
 262 }
 263
 264 /*
 265  * logger_read - our log's read() method
 266  *
 267  * Behavior:
 268  *
 269  *      - O_NONBLOCK works
 270  *      - If there are no log entries to read, blocks until log is written to
 271  *      - Atomically reads exactly one log entry
 272  *
 273  * Will set errno to EINVAL if read
 274  * buffer is insufficient to hold next entry.
 275  */
 276 static ssize_t logger_read(struct file *file, char __user *buf,
 277                            size_t count, loff_t *pos)
 278 {
 279         struct logger_reader *reader = file->private_data;
 280         struct logger_log *log = reader->log;
 281         ssize_t ret;
 282         DEFINE_WAIT(wait);
 283
 284 start:
 285         while (1) {
 286                 mutex_lock(&log->mutex);
 287
 288                 prepare_to_wait(&log->wq, &wait, TASK_INTERRUPTIBLE);
 289
 290                 ret = (log->w_off == reader->r_off);
 291                 mutex_unlock(&log->mutex);
 292                 if (!ret)
 293                         break;
 294
 295                 if (file->f_flags & O_NONBLOCK) {
 296                         ret = -EAGAIN;
 297                         break;
 298                 }
 299
 300                 if (signal_pending(current)) {
 301                         ret = -EINTR;
 302                         break;
 303                 }
 304
 305                 schedule();
 306         }
 307
 308         finish_wait(&log->wq, &wait);
 309         if (ret)
 310                 return ret;
 311
 312         mutex_lock(&log->mutex);
 313
 314         if (!reader->r_all)
 315                 reader->r_off = get_next_entry_by_uid(log,
 316                         reader->r_off, current_euid());
 317
 318         /* is there still something to read or did we race? */
 319         if (unlikely(log->w_off == reader->r_off)) {
 320                 mutex_unlock(&log->mutex);
 321                 goto start;
 322         }
 323
 324         /* get the size of the next entry */
 325         ret = get_user_hdr_len(reader->r_ver) +
 326                 get_entry_msg_len(log, reader->r_off);
 327         if (count < ret) {
 328                 ret = -EINVAL;
 329                 goto out;
 330         }
 331
 332         /* get exactly one entry from the log */
 333         ret = do_read_log_to_user(log, reader, buf, ret);
 334
 335 out:
 336         mutex_unlock(&log->mutex);
 337
 338         return ret;
 339 }
 340
 341 /*
 342  * get_next_entry - return the offset of the first valid entry at least 'len'
 343  * bytes after 'off'.
 344  *
 345  * Caller must hold log->mutex.
 346  */
 347 static size_t get_next_entry(struct logger_log *log, size_t off, size_t len)
 348 {
 349         size_t count = 0;
 350
 351         do {
 352                 size_t nr = sizeof(struct logger_entry) +
 353                         get_entry_msg_len(log, off);
 354                 off = logger_offset(log, off + nr);
 355                 count += nr;
 356         } while (count < len);
 357
 358         return off;
 359 }
 360
 361 /*
 362  * is_between - is a < c < b, accounting for wrapping of a, b, and c
 363  *    positions in the buffer
 364  *
 365  * That is, if a<b, check for c between a and b
 366  * and if a>b, check for c outside (not between) a and b
 367  *
 368  * |------- a xxxxxxxx b --------|
 369  *               c^
 370  *
 371  * |xxxxx b --------- a xxxxxxxxx|
 372  *    c^
 373  *  or                    c^
 374  */
 375 static inline int is_between(size_t a, size_t b, size_t c)
 376 {
 377         if (a < b) {
 378                 /* is c between a and b? */
 379                 if (a < c && c <= b)
 380                         return 1;
 381         } else {
 382                 /* is c outside of b through a? */
 383                 if (c <= b || a < c)
 384                         return 1;
 385         }
 386
 387         return 0;
 388 }
 389
 390 /*
 391  * fix_up_readers - walk the list of all readers and "fix up" any who were
 392  * lapped by the writer; also do the same for the default "start head".
 393  * We do this by "pulling forward" the readers and start head to the first
 394  * entry after the new write head.
 395  *
 396  * The caller needs to hold log->mutex.
 397  */
 398 static void fix_up_readers(struct logger_log *log, size_t len)
 399 {
 400         size_t old = log->w_off;
 401         size_t new = logger_offset(log, old + len);
 402         struct logger_reader *reader;
 403
 404         if (is_between(old, new, log->head))
 405                 log->head = get_next_entry(log, log->head, len);
 406
 407         list_for_each_entry(reader, &log->readers, list)
 408                 if (is_between(old, new, reader->r_off))
 409                         reader->r_off = get_next_entry(log, reader->r_off, len);
 410 }
 411
 412 /*
 413  * logger_write_iter - our write method, implementing support for write(),
 414  * writev(), and aio_write(). Writes are our fast path, and we try to optimize
 415  * them above all else.
 416  */
 417 static ssize_t logger_write_iter(struct kiocb *iocb, struct iov_iter *from)
 418 {
 419         struct logger_log *log = file_get_log(iocb->ki_filp);
 420         struct logger_entry header;
 421         struct timespec now;
 422         size_t len, count, w_off;
 423
 424         count = min_t(size_t, iocb->ki_nbytes, LOGGER_ENTRY_MAX_PAYLOAD);
 425
 426         now = current_kernel_time();
 427
 428         header.pid = current->tgid;
 429         header.tid = current->pid;
 430         header.sec = now.tv_sec;
 431         header.nsec = now.tv_nsec;
 432         header.euid = current_euid();
 433         header.len = count;
 434         header.hdr_size = sizeof(struct logger_entry);
 435
 436         /* null writes succeed, return zero */
 437         if (unlikely(!header.len))
 438                 return 0;
 439
 440         mutex_lock(&log->mutex);
 441
 442         /*
 443          * Fix up any readers, pulling them forward to the first readable
 444          * entry after (what will be) the new write offset. We do this now
 445          * because if we partially fail, we can end up with clobbered log
 446          * entries that encroach on readable buffer.
 447          */
 448         fix_up_readers(log, sizeof(struct logger_entry) + header.len);
 449
 450         len = min(sizeof(header), log->size - log->w_off);
 451         memcpy(log->buffer + log->w_off, &header, len);
 452         memcpy(log->buffer, (char *)&header + len, sizeof(header) - len);
 453
 454         /* Work with a copy until we are ready to commit the whole entry */
 455         w_off =  logger_offset(log, log->w_off + sizeof(struct logger_entry));
 456
 457         len = min(count, log->size - w_off);
 458
 459         if (copy_from_iter(log->buffer + w_off, len, from) != len) {
 460                 /*
 461                  * Note that by not updating log->w_off, this abandons the
 462                  * portion of the new entry that *was* successfully
 463                  * copied, just above.  This is intentional to avoid
 464                  * message corruption from missing fragments.
 465                  */
 466                 mutex_unlock(&log->mutex);
 467                 return -EFAULT;
 468         }
 469
 470         if (copy_from_iter(log->buffer, count - len, from) != count - len) {
 471                 mutex_unlock(&log->mutex);
 472                 return -EFAULT;
 473         }
 474
 475         log->w_off = logger_offset(log, w_off + count);
 476         mutex_unlock(&log->mutex);
 477
 478         /* wake up any blocked readers */
 479         wake_up_interruptible(&log->wq);
 480
 481         return len;
 482 }
 483
 484 static struct logger_log *get_log_from_minor(int minor)
 485 {
 486         struct logger_log *log;
 487
 488         list_for_each_entry(log, &log_list, logs)
 489                 if (log->misc.minor == minor)
 490                         return log;
 491         return NULL;
 492 }
 493
 494 /*
 495  * logger_open - the log's open() file operation
 496  *
 497  * Note how near a no-op this is in the write-only case. Keep it that way!
 498  */
 499 static int logger_open(struct inode *inode, struct file *file)
 500 {
 501         struct logger_log *log;
 502         int ret;
 503
 504         ret = nonseekable_open(inode, file);
 505         if (ret)
 506                 return ret;
 507
 508         log = get_log_from_minor(MINOR(inode->i_rdev));
 509         if (!log)
 510                 return -ENODEV;
 511
 512         if (file->f_mode & FMODE_READ) {
 513                 struct logger_reader *reader;
 514
 515                 reader = kmalloc(sizeof(struct logger_reader), GFP_KERNEL);
 516                 if (!reader)
 517                         return -ENOMEM;
 518
 519                 reader->log = log;
 520                 reader->r_ver = 1;
 521                 reader->r_all = in_egroup_p(inode->i_gid) ||
 522                         capable(CAP_SYSLOG);
 523
 524                 INIT_LIST_HEAD(&reader->list);
 525
 526                 mutex_lock(&log->mutex);
 527                 reader->r_off = log->head;
 528                 list_add_tail(&reader->list, &log->readers);
 529                 mutex_unlock(&log->mutex);
 530
 531                 file->private_data = reader;
 532         } else {
 533                 file->private_data = log;
 534         }
 535
 536         return 0;
 537 }
 538
 539 /*
 540  * logger_release - the log's release file operation
 541  *
 542  * Note this is a total no-op in the write-only case. Keep it that way!
 543  */
 544 static int logger_release(struct inode *ignored, struct file *file)
 545 {
 546         if (file->f_mode & FMODE_READ) {
 547                 struct logger_reader *reader = file->private_data;
 548                 struct logger_log *log = reader->log;
 549
 550                 mutex_lock(&log->mutex);
 551                 list_del(&reader->list);
 552                 mutex_unlock(&log->mutex);
 553
 554                 kfree(reader);
 555         }
 556
 557         return 0;
 558 }
 559
 560 /*
 561  * logger_poll - the log's poll file operation, for poll/select/epoll
 562  *
 563  * Note we always return POLLOUT, because you can always write() to the log.
 564  * Note also that, strictly speaking, a return value of POLLIN does not
 565  * guarantee that the log is readable without blocking, as there is a small
 566  * chance that the writer can lap the reader in the interim between poll()
 567  * returning and the read() request.
 568  */
 569 static unsigned int logger_poll(struct file *file, poll_table *wait)
 570 {
 571         struct logger_reader *reader;
 572         struct logger_log *log;
 573         unsigned int ret = POLLOUT | POLLWRNORM;
 574
 575         if (!(file->f_mode & FMODE_READ))
 576                 return ret;
 577
 578         reader = file->private_data;
 579         log = reader->log;
 580
 581         poll_wait(file, &log->wq, wait);
 582
 583         mutex_lock(&log->mutex);
 584         if (!reader->r_all)
 585                 reader->r_off = get_next_entry_by_uid(log,
 586                         reader->r_off, current_euid());
 587
 588         if (log->w_off != reader->r_off)
 589                 ret |= POLLIN | POLLRDNORM;
 590         mutex_unlock(&log->mutex);
 591
 592         return ret;
 593 }
 594
 595 static long logger_set_version(struct logger_reader *reader, void __user *arg)
 596 {
 597         int version;
 598
 599         if (copy_from_user(&version, arg, sizeof(int)))
 600                 return -EFAULT;
 601
 602         if ((version < 1) || (version > 2))
 603                 return -EINVAL;
 604
 605         reader->r_ver = version;
 606         return 0;
 607 }
 608
 609 static long logger_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 610 {
 611         struct logger_log *log = file_get_log(file);
 612         struct logger_reader *reader;
 613         long ret = -EINVAL;
 614         void __user *argp = (void __user *)arg;
 615
 616         mutex_lock(&log->mutex);
 617
 618         switch (cmd) {
 619         case LOGGER_GET_LOG_BUF_SIZE:
 620                 ret = log->size;
 621                 break;
 622         case LOGGER_GET_LOG_LEN:
 623                 if (!(file->f_mode & FMODE_READ)) {
 624                         ret = -EBADF;
 625                         break;
 626                 }
 627                 reader = file->private_data;
 628                 if (log->w_off >= reader->r_off)
 629                         ret = log->w_off - reader->r_off;
 630                 else
 631                         ret = (log->size - reader->r_off) + log->w_off;
 632                 break;
 633         case LOGGER_GET_NEXT_ENTRY_LEN:
 634                 if (!(file->f_mode & FMODE_READ)) {
 635                         ret = -EBADF;
 636                         break;
 637                 }
 638                 reader = file->private_data;
 639
 640                 if (!reader->r_all)
 641                         reader->r_off = get_next_entry_by_uid(log,
 642                                 reader->r_off, current_euid());
 643
 644                 if (log->w_off != reader->r_off)
 645                         ret = get_user_hdr_len(reader->r_ver) +
 646                                 get_entry_msg_len(log, reader->r_off);
 647                 else
 648                         ret = 0;
 649                 break;
 650         case LOGGER_FLUSH_LOG:
 651                 if (!(file->f_mode & FMODE_WRITE)) {
 652                         ret = -EBADF;
 653                         break;
 654                 }
 655                 if (!(in_egroup_p(file_inode(file)->i_gid) ||
 656                       capable(CAP_SYSLOG))) {
 657                         ret = -EPERM;
 658                         break;
 659                 }
 660                 list_for_each_entry(reader, &log->readers, list)
 661                         reader->r_off = log->w_off;
 662                 log->head = log->w_off;
 663                 ret = 0;
 664                 break;
 665         case LOGGER_GET_VERSION:
 666                 if (!(file->f_mode & FMODE_READ)) {
 667                         ret = -EBADF;
 668                         break;
 669                 }
 670                 reader = file->private_data;
 671                 ret = reader->r_ver;
 672                 break;
 673         case LOGGER_SET_VERSION:
 674                 if (!(file->f_mode & FMODE_READ)) {
 675                         ret = -EBADF;
 676                         break;
 677                 }
 678                 reader = file->private_data;
 679                 ret = logger_set_version(reader, argp);
 680                 break;
 681         }
 682
 683         mutex_unlock(&log->mutex);
 684
 685         return ret;
 686 }
 687
 688 static const struct file_operations logger_fops = {
 689         .owner = THIS_MODULE,
 690         .read = logger_read,
 691         .write_iter = logger_write_iter,
 692         .poll = logger_poll,
 693         .unlocked_ioctl = logger_ioctl,
 694         .compat_ioctl = logger_ioctl,
 695         .open = logger_open,
 696         .release = logger_release,
 697 };
 698
 699 /*
 700  * Log size must must be a power of two, and greater than
 701  * (LOGGER_ENTRY_MAX_PAYLOAD + sizeof(struct logger_entry)).
 702  */
 703 static int __init create_log(char *log_name, int size)
 704 {
 705         int ret = 0;
 706         struct logger_log *log;
 707         unsigned char *buffer;
 708
 709         buffer = vmalloc(size);
 710         if (buffer == NULL)
 711                 return -ENOMEM;
 712
 713         log = kzalloc(sizeof(struct logger_log), GFP_KERNEL);
 714         if (log == NULL) {
 715                 ret = -ENOMEM;
 716                 goto out_free_buffer;
 717         }
 718         log->buffer = buffer;
 719
 720         log->misc.minor = MISC_DYNAMIC_MINOR;
 721         log->misc.name = kstrdup(log_name, GFP_KERNEL);
 722         if (log->misc.name == NULL) {
 723                 ret = -ENOMEM;
 724                 goto out_free_log;
 725         }
 726
 727         log->misc.fops = &logger_fops;
 728         log->misc.parent = NULL;
 729
 730         init_waitqueue_head(&log->wq);
 731         INIT_LIST_HEAD(&log->readers);
 732         mutex_init(&log->mutex);
 733         log->w_off = 0;
 734         log->head = 0;
 735         log->size = size;
 736
 737         INIT_LIST_HEAD(&log->logs);
 738         list_add_tail(&log->logs, &log_list);
 739
 740         /* finally, initialize the misc device for this log */
 741         ret = misc_register(&log->misc);
 742         if (unlikely(ret)) {
 743                 pr_err("failed to register misc device for log '%s'!\n",
 744                        log->misc.name);
 745                 goto out_free_misc_name;
 746         }
 747
 748         pr_info("created %luK log '%s'\n",
 749                 (unsigned long)log->size >> 10, log->misc.name);
 750
 751         return 0;
 752
 753 out_free_misc_name:
 754         kfree(log->misc.name);
 755
 756 out_free_log:
 757         kfree(log);
 758
 759 out_free_buffer:
 760         vfree(buffer);
 761         return ret;
 762 }
 763
 764 static int __init logger_init(void)
 765 {
 766         int ret;
 767
 768         ret = create_log(LOGGER_LOG_MAIN, 256*1024);
 769         if (unlikely(ret))
 770                 goto out;
 771
 772         ret = create_log(LOGGER_LOG_EVENTS, 256*1024);
 773         if (unlikely(ret))
 774                 goto out;
 775
 776         ret = create_log(LOGGER_LOG_RADIO, 256*1024);
 777         if (unlikely(ret))
 778                 goto out;
 779
 780         ret = create_log(LOGGER_LOG_SYSTEM, 256*1024);
 781         if (unlikely(ret))
 782                 goto out;
 783
 784 out:
 785         return ret;
 786 }
 787
 788 static void __exit logger_exit(void)
 789 {
 790         struct logger_log *current_log, *next_log;
 791
 792         list_for_each_entry_safe(current_log, next_log, &log_list, logs) {
 793                 /* we have to delete all the entry inside log_list */
 794                 misc_deregister(&current_log->misc);
 795                 vfree(current_log->buffer);
 796                 kfree(current_log->misc.name);
 797                 list_del(&current_log->logs);
 798                 kfree(current_log);
 799         }
 800 }
 801
 802 device_initcall(logger_init);
 803 module_exit(logger_exit);
 804
 805 MODULE_LICENSE("GPL");
 806 MODULE_AUTHOR("Robert Love, <rlove@google.com>");
 807 MODULE_DESCRIPTION("Android Logger");