lib/dma-debug.c

   1 /*
   2  * Copyright (C) 2008 Advanced Micro Devices, Inc.
   3  *
   4  * Author: Joerg Roedel <joerg.roedel@amd.com>
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License version 2 as published
   8  * by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  18  */
  19
  20 #include <linux/scatterlist.h>
  21 #include <linux/dma-mapping.h>
  22 #include <linux/stacktrace.h>
  23 #include <linux/dma-debug.h>
  24 #include <linux/spinlock.h>
  25 #include <linux/debugfs.h>
  26 #include <linux/uaccess.h>
  27 #include <linux/export.h>
  28 #include <linux/device.h>
  29 #include <linux/types.h>
  30 #include <linux/sched.h>
  31 #include <linux/ctype.h>
  32 #include <linux/list.h>
  33 #include <linux/slab.h>
  34
  35 #include <asm/sections.h>
  36
  37 #define HASH_SIZE       1024ULL
  38 #define HASH_FN_SHIFT   13
  39 #define HASH_FN_MASK    (HASH_SIZE - 1)
  40
  41 enum {
  42         dma_debug_single,
  43         dma_debug_page,
  44         dma_debug_sg,
  45         dma_debug_coherent,
  46 };
  47
  48 enum map_err_types {
  49         MAP_ERR_CHECK_NOT_APPLICABLE,
  50         MAP_ERR_NOT_CHECKED,
  51         MAP_ERR_CHECKED,
  52 };
  53
  54 #define DMA_DEBUG_STACKTRACE_ENTRIES 5
  55
  56 struct dma_debug_entry {
  57         struct list_head list;
  58         struct device    *dev;
  59         int              type;
  60         phys_addr_t      paddr;
  61         u64              dev_addr;
  62         u64              size;
  63         int              direction;
  64         int              sg_call_ents;
  65         int              sg_mapped_ents;
  66         enum map_err_types  map_err_type;
  67 #ifdef CONFIG_STACKTRACE
  68         struct           stack_trace stacktrace;
  69         unsigned long    st_entries[DMA_DEBUG_STACKTRACE_ENTRIES];
  70 #endif
  71 };
  72
  73 typedef bool (*match_fn)(struct dma_debug_entry *, struct dma_debug_entry *);
  74
  75 struct hash_bucket {
  76         struct list_head list;
  77         spinlock_t lock;
  78 } ____cacheline_aligned_in_smp;
  79
  80 /* Hash list to save the allocated dma addresses */
  81 static struct hash_bucket dma_entry_hash[HASH_SIZE];
  82 /* List of pre-allocated dma_debug_entry's */
  83 static LIST_HEAD(free_entries);
  84 /* Lock for the list above */
  85 static DEFINE_SPINLOCK(free_entries_lock);
  86
  87 /* Global disable flag - will be set in case of an error */
  88 static u32 global_disable __read_mostly;
  89
  90 /* Global error count */
  91 static u32 error_count;
  92
  93 /* Global error show enable*/
  94 static u32 show_all_errors __read_mostly;
  95 /* Number of errors to show */
  96 static u32 show_num_errors = 1;
  97
  98 static u32 num_free_entries;
  99 static u32 min_free_entries;
 100 static u32 nr_total_entries;
 101
 102 /* number of preallocated entries requested by kernel cmdline */
 103 static u32 req_entries;
 104
 105 /* debugfs dentry's for the stuff above */
 106 static struct dentry *dma_debug_dent        __read_mostly;
 107 static struct dentry *global_disable_dent   __read_mostly;
 108 static struct dentry *error_count_dent      __read_mostly;
 109 static struct dentry *show_all_errors_dent  __read_mostly;
 110 static struct dentry *show_num_errors_dent  __read_mostly;
 111 static struct dentry *num_free_entries_dent __read_mostly;
 112 static struct dentry *min_free_entries_dent __read_mostly;
 113 static struct dentry *filter_dent           __read_mostly;
 114
 115 /* per-driver filter related state */
 116
 117 #define NAME_MAX_LEN    64
 118
 119 static char                  current_driver_name[NAME_MAX_LEN] __read_mostly;
 120 static struct device_driver *current_driver                    __read_mostly;
 121
 122 static DEFINE_RWLOCK(driver_name_lock);
 123
 124 static const char *const maperr2str[] = {
 125         [MAP_ERR_CHECK_NOT_APPLICABLE] = "dma map error check not applicable",
 126         [MAP_ERR_NOT_CHECKED] = "dma map error not checked",
 127         [MAP_ERR_CHECKED] = "dma map error checked",
 128 };
 129
 130 static const char *type2name[4] = { "single", "page",
 131                                     "scather-gather", "coherent" };
 132
 133 static const char *dir2name[4] = { "DMA_BIDIRECTIONAL", "DMA_TO_DEVICE",
 134                                    "DMA_FROM_DEVICE", "DMA_NONE" };
 135
 136 /*
 137  * The access to some variables in this macro is racy. We can't use atomic_t
 138  * here because all these variables are exported to debugfs. Some of them even
 139  * writeable. This is also the reason why a lock won't help much. But anyway,
 140  * the races are no big deal. Here is why:
 141  *
 142  *   error_count: the addition is racy, but the worst thing that can happen is
 143  *                that we don't count some errors
 144  *   show_num_errors: the subtraction is racy. Also no big deal because in
 145  *                    worst case this will result in one warning more in the
 146  *                    system log than the user configured. This variable is
 147  *                    writeable via debugfs.
 148  */
 149 static inline void dump_entry_trace(struct dma_debug_entry *entry)
 150 {
 151 #ifdef CONFIG_STACKTRACE
 152         if (entry) {
 153                 pr_warning("Mapped at:\n");
 154                 print_stack_trace(&entry->stacktrace, 0);
 155         }
 156 #endif
 157 }
 158
 159 static bool driver_filter(struct device *dev)
 160 {
 161         struct device_driver *drv;
 162         unsigned long flags;
 163         bool ret;
 164
 165         /* driver filter off */
 166         if (likely(!current_driver_name[0]))
 167                 return true;
 168
 169         /* driver filter on and initialized */
 170         if (current_driver && dev && dev->driver == current_driver)
 171                 return true;
 172
 173         /* driver filter on, but we can't filter on a NULL device... */
 174         if (!dev)
 175                 return false;
 176
 177         if (current_driver || !current_driver_name[0])
 178                 return false;
 179
 180         /* driver filter on but not yet initialized */
 181         drv = dev->driver;
 182         if (!drv)
 183                 return false;
 184
 185         /* lock to protect against change of current_driver_name */
 186         read_lock_irqsave(&driver_name_lock, flags);
 187
 188         ret = false;
 189         if (drv->name &&
 190             strncmp(current_driver_name, drv->name, NAME_MAX_LEN - 1) == 0) {
 191                 current_driver = drv;
 192                 ret = true;
 193         }
 194
 195         read_unlock_irqrestore(&driver_name_lock, flags);
 196
 197         return ret;
 198 }
 199
 200 #define err_printk(dev, entry, format, arg...) do {                     \
 201                 error_count += 1;                                       \
 202                 if (driver_filter(dev) &&                               \
 203                     (show_all_errors || show_num_errors > 0)) {         \
 204                         WARN(1, "%s %s: " format,                       \
 205                              dev ? dev_driver_string(dev) : "NULL",     \
 206                              dev ? dev_name(dev) : "NULL", ## arg);     \
 207                         dump_entry_trace(entry);                        \
 208                 }                                                       \
 209                 if (!show_all_errors && show_num_errors > 0)            \
 210                         show_num_errors -= 1;                           \
 211         } while (0);
 212
 213 /*
 214  * Hash related functions
 215  *
 216  * Every DMA-API request is saved into a struct dma_debug_entry. To
 217  * have quick access to these structs they are stored into a hash.
 218  */
 219 static int hash_fn(struct dma_debug_entry *entry)
 220 {
 221         /*
 222          * Hash function is based on the dma address.
 223          * We use bits 20-27 here as the index into the hash
 224          */
 225         return (entry->dev_addr >> HASH_FN_SHIFT) & HASH_FN_MASK;
 226 }
 227
 228 /*
 229  * Request exclusive access to a hash bucket for a given dma_debug_entry.
 230  */
 231 static struct hash_bucket *get_hash_bucket(struct dma_debug_entry *entry,
 232                                            unsigned long *flags)
 233 {
 234         int idx = hash_fn(entry);
 235         unsigned long __flags;
 236
 237         spin_lock_irqsave(&dma_entry_hash[idx].lock, __flags);
 238         *flags = __flags;
 239         return &dma_entry_hash[idx];
 240 }
 241
 242 /*
 243  * Give up exclusive access to the hash bucket
 244  */
 245 static void put_hash_bucket(struct hash_bucket *bucket,
 246                             unsigned long *flags)
 247 {
 248         unsigned long __flags = *flags;
 249
 250         spin_unlock_irqrestore(&bucket->lock, __flags);
 251 }
 252
 253 static bool exact_match(struct dma_debug_entry *a, struct dma_debug_entry *b)
 254 {
 255         return ((a->dev_addr == b->dev_addr) &&
 256                 (a->dev == b->dev)) ? true : false;
 257 }
 258
 259 static bool containing_match(struct dma_debug_entry *a,
 260                              struct dma_debug_entry *b)
 261 {
 262         if (a->dev != b->dev)
 263                 return false;
 264
 265         if ((b->dev_addr <= a->dev_addr) &&
 266             ((b->dev_addr + b->size) >= (a->dev_addr + a->size)))
 267                 return true;
 268
 269         return false;
 270 }
 271
 272 /*
 273  * Search a given entry in the hash bucket list
 274  */
 275 static struct dma_debug_entry *__hash_bucket_find(struct hash_bucket *bucket,
 276                                                   struct dma_debug_entry *ref,
 277                                                   match_fn match)
 278 {
 279         struct dma_debug_entry *entry, *ret = NULL;
 280         int matches = 0, match_lvl, last_lvl = -1;
 281
 282         list_for_each_entry(entry, &bucket->list, list) {
 283                 if (!match(ref, entry))
 284                         continue;
 285
 286                 /*
 287                  * Some drivers map the same physical address multiple
 288                  * times. Without a hardware IOMMU this results in the
 289                  * same device addresses being put into the dma-debug
 290                  * hash multiple times too. This can result in false
 291                  * positives being reported. Therefore we implement a
 292                  * best-fit algorithm here which returns the entry from
 293                  * the hash which fits best to the reference value
 294                  * instead of the first-fit.
 295                  */
 296                 matches += 1;
 297                 match_lvl = 0;
 298                 entry->size         == ref->size         ? ++match_lvl : 0;
 299                 entry->type         == ref->type         ? ++match_lvl : 0;
 300                 entry->direction    == ref->direction    ? ++match_lvl : 0;
 301                 entry->sg_call_ents == ref->sg_call_ents ? ++match_lvl : 0;
 302
 303                 if (match_lvl == 4) {
 304                         /* perfect-fit - return the result */
 305                         return entry;
 306                 } else if (match_lvl > last_lvl) {
 307                         /*
 308                          * We found an entry that fits better then the
 309                          * previous one or it is the 1st match.
 310                          */
 311                         last_lvl = match_lvl;
 312                         ret      = entry;
 313                 }
 314         }
 315
 316         /*
 317          * If we have multiple matches but no perfect-fit, just return
 318          * NULL.
 319          */
 320         ret = (matches == 1) ? ret : NULL;
 321
 322         return ret;
 323 }
 324
 325 static struct dma_debug_entry *bucket_find_exact(struct hash_bucket *bucket,
 326                                                  struct dma_debug_entry *ref)
 327 {
 328         return __hash_bucket_find(bucket, ref, exact_match);
 329 }
 330
 331 static struct dma_debug_entry *bucket_find_contain(struct hash_bucket **bucket,
 332                                                    struct dma_debug_entry *ref,
 333                                                    unsigned long *flags)
 334 {
 335
 336         unsigned int max_range = dma_get_max_seg_size(ref->dev);
 337         struct dma_debug_entry *entry, index = *ref;
 338         unsigned int range = 0;
 339
 340         while (range <= max_range) {
 341                 entry = __hash_bucket_find(*bucket, &index, containing_match);
 342
 343                 if (entry)
 344                         return entry;
 345
 346                 /*
 347                  * Nothing found, go back a hash bucket
 348                  */
 349                 put_hash_bucket(*bucket, flags);
 350                 range          += (1 << HASH_FN_SHIFT);
 351                 index.dev_addr -= (1 << HASH_FN_SHIFT);
 352                 *bucket = get_hash_bucket(&index, flags);
 353         }
 354
 355         return NULL;
 356 }
 357
 358 /*
 359  * Add an entry to a hash bucket
 360  */
 361 static void hash_bucket_add(struct hash_bucket *bucket,
 362                             struct dma_debug_entry *entry)
 363 {
 364         list_add_tail(&entry->list, &bucket->list);
 365 }
 366
 367 /*
 368  * Remove entry from a hash bucket list
 369  */
 370 static void hash_bucket_del(struct dma_debug_entry *entry)
 371 {
 372         list_del(&entry->list);
 373 }
 374
 375 /*
 376  * Dump mapping entries for debugging purposes
 377  */
 378 void debug_dma_dump_mappings(struct device *dev)
 379 {
 380         int idx;
 381
 382         for (idx = 0; idx < HASH_SIZE; idx++) {
 383                 struct hash_bucket *bucket = &dma_entry_hash[idx];
 384                 struct dma_debug_entry *entry;
 385                 unsigned long flags;
 386
 387                 spin_lock_irqsave(&bucket->lock, flags);
 388
 389                 list_for_each_entry(entry, &bucket->list, list) {
 390                         if (!dev || dev == entry->dev) {
 391                                 dev_info(entry->dev,
 392                                          "%s idx %d P=%Lx D=%Lx L=%Lx %s %s\n",
 393                                          type2name[entry->type], idx,
 394                                          (unsigned long long)entry->paddr,
 395                                          entry->dev_addr, entry->size,
 396                                          dir2name[entry->direction],
 397                                          maperr2str[entry->map_err_type]);
 398                         }
 399                 }
 400
 401                 spin_unlock_irqrestore(&bucket->lock, flags);
 402         }
 403 }
 404 EXPORT_SYMBOL(debug_dma_dump_mappings);
 405
 406 /*
 407  * Wrapper function for adding an entry to the hash.
 408  * This function takes care of locking itself.
 409  */
 410 static void add_dma_entry(struct dma_debug_entry *entry)
 411 {
 412         struct hash_bucket *bucket;
 413         unsigned long flags;
 414
 415         bucket = get_hash_bucket(entry, &flags);
 416         hash_bucket_add(bucket, entry);
 417         put_hash_bucket(bucket, &flags);
 418 }
 419
 420 static struct dma_debug_entry *__dma_entry_alloc(void)
 421 {
 422         struct dma_debug_entry *entry;
 423
 424         entry = list_entry(free_entries.next, struct dma_debug_entry, list);
 425         list_del(&entry->list);
 426         memset(entry, 0, sizeof(*entry));
 427
 428         num_free_entries -= 1;
 429         if (num_free_entries < min_free_entries)
 430                 min_free_entries = num_free_entries;
 431
 432         return entry;
 433 }
 434
 435 /* struct dma_entry allocator
 436  *
 437  * The next two functions implement the allocator for
 438  * struct dma_debug_entries.
 439  */
 440 static struct dma_debug_entry *dma_entry_alloc(void)
 441 {
 442         struct dma_debug_entry *entry;
 443         unsigned long flags;
 444
 445         spin_lock_irqsave(&free_entries_lock, flags);
 446
 447         if (list_empty(&free_entries)) {
 448                 pr_err("DMA-API: debugging out of memory - disabling\n");
 449                 global_disable = true;
 450                 spin_unlock_irqrestore(&free_entries_lock, flags);
 451                 return NULL;
 452         }
 453
 454         entry = __dma_entry_alloc();
 455
 456         spin_unlock_irqrestore(&free_entries_lock, flags);
 457
 458 #ifdef CONFIG_STACKTRACE
 459         entry->stacktrace.max_entries = DMA_DEBUG_STACKTRACE_ENTRIES;
 460         entry->stacktrace.entries = entry->st_entries;
 461         entry->stacktrace.skip = 2;
 462         save_stack_trace(&entry->stacktrace);
 463 #endif
 464
 465         return entry;
 466 }
 467
 468 static void dma_entry_free(struct dma_debug_entry *entry)
 469 {
 470         unsigned long flags;
 471
 472         /*
 473          * add to beginning of the list - this way the entries are
 474          * more likely cache hot when they are reallocated.
 475          */
 476         spin_lock_irqsave(&free_entries_lock, flags);
 477         list_add(&entry->list, &free_entries);
 478         num_free_entries += 1;
 479         spin_unlock_irqrestore(&free_entries_lock, flags);
 480 }
 481
 482 int dma_debug_resize_entries(u32 num_entries)
 483 {
 484         int i, delta, ret = 0;
 485         unsigned long flags;
 486         struct dma_debug_entry *entry;
 487         LIST_HEAD(tmp);
 488
 489         spin_lock_irqsave(&free_entries_lock, flags);
 490
 491         if (nr_total_entries < num_entries) {
 492                 delta = num_entries - nr_total_entries;
 493
 494                 spin_unlock_irqrestore(&free_entries_lock, flags);
 495
 496                 for (i = 0; i < delta; i++) {
 497                         entry = kzalloc(sizeof(*entry), GFP_KERNEL);
 498                         if (!entry)
 499                                 break;
 500
 501                         list_add_tail(&entry->list, &tmp);
 502                 }
 503
 504                 spin_lock_irqsave(&free_entries_lock, flags);
 505
 506                 list_splice(&tmp, &free_entries);
 507                 nr_total_entries += i;
 508                 num_free_entries += i;
 509         } else {
 510                 delta = nr_total_entries - num_entries;
 511
 512                 for (i = 0; i < delta && !list_empty(&free_entries); i++) {
 513                         entry = __dma_entry_alloc();
 514                         kfree(entry);
 515                 }
 516
 517                 nr_total_entries -= i;
 518         }
 519
 520         if (nr_total_entries != num_entries)
 521                 ret = 1;
 522
 523         spin_unlock_irqrestore(&free_entries_lock, flags);
 524
 525         return ret;
 526 }
 527 EXPORT_SYMBOL(dma_debug_resize_entries);
 528
 529 /*
 530  * DMA-API debugging init code
 531  *
 532  * The init code does two things:
 533  *   1. Initialize core data structures
 534  *   2. Preallocate a given number of dma_debug_entry structs
 535  */
 536
 537 static int prealloc_memory(u32 num_entries)
 538 {
 539         struct dma_debug_entry *entry, *next_entry;
 540         int i;
 541
 542         for (i = 0; i < num_entries; ++i) {
 543                 entry = kzalloc(sizeof(*entry), GFP_KERNEL);
 544                 if (!entry)
 545                         goto out_err;
 546
 547                 list_add_tail(&entry->list, &free_entries);
 548         }
 549
 550         num_free_entries = num_entries;
 551         min_free_entries = num_entries;
 552
 553         pr_info("DMA-API: preallocated %d debug entries\n", num_entries);
 554
 555         return 0;
 556
 557 out_err:
 558
 559         list_for_each_entry_safe(entry, next_entry, &free_entries, list) {
 560                 list_del(&entry->list);
 561                 kfree(entry);
 562         }
 563
 564         return -ENOMEM;
 565 }
 566
 567 static ssize_t filter_read(struct file *file, char __user *user_buf,
 568                            size_t count, loff_t *ppos)
 569 {
 570         char buf[NAME_MAX_LEN + 1];
 571         unsigned long flags;
 572         int len;
 573
 574         if (!current_driver_name[0])
 575                 return 0;
 576
 577         /*
 578          * We can't copy to userspace directly because current_driver_name can
 579          * only be read under the driver_name_lock with irqs disabled. So
 580          * create a temporary copy first.
 581          */
 582         read_lock_irqsave(&driver_name_lock, flags);
 583         len = scnprintf(buf, NAME_MAX_LEN + 1, "%s\n", current_driver_name);
 584         read_unlock_irqrestore(&driver_name_lock, flags);
 585
 586         return simple_read_from_buffer(user_buf, count, ppos, buf, len);
 587 }
 588
 589 static ssize_t filter_write(struct file *file, const char __user *userbuf,
 590                             size_t count, loff_t *ppos)
 591 {
 592         char buf[NAME_MAX_LEN];
 593         unsigned long flags;
 594         size_t len;
 595         int i;
 596
 597         /*
 598          * We can't copy from userspace directly. Access to
 599          * current_driver_name is protected with a write_lock with irqs
 600          * disabled. Since copy_from_user can fault and may sleep we
 601          * need to copy to temporary buffer first
 602          */
 603         len = min(count, (size_t)(NAME_MAX_LEN - 1));
 604         if (copy_from_user(buf, userbuf, len))
 605                 return -EFAULT;
 606
 607         buf[len] = 0;
 608
 609         write_lock_irqsave(&driver_name_lock, flags);
 610
 611         /*
 612          * Now handle the string we got from userspace very carefully.
 613          * The rules are:
 614          *         - only use the first token we got
 615          *         - token delimiter is everything looking like a space
 616          *           character (' ', '\n', '\t' ...)
 617          *
 618          */
 619         if (!isalnum(buf[0])) {
 620                 /*
 621                  * If the first character userspace gave us is not
 622                  * alphanumerical then assume the filter should be
 623                  * switched off.
 624                  */
 625                 if (current_driver_name[0])
 626                         pr_info("DMA-API: switching off dma-debug driver filter\n");
 627                 current_driver_name[0] = 0;
 628                 current_driver = NULL;
 629                 goto out_unlock;
 630         }
 631
 632         /*
 633          * Now parse out the first token and use it as the name for the
 634          * driver to filter for.
 635          */
 636         for (i = 0; i < NAME_MAX_LEN - 1; ++i) {
 637                 current_driver_name[i] = buf[i];
 638                 if (isspace(buf[i]) || buf[i] == ' ' || buf[i] == 0)
 639                         break;
 640         }
 641         current_driver_name[i] = 0;
 642         current_driver = NULL;
 643
 644         pr_info("DMA-API: enable driver filter for driver [%s]\n",
 645                 current_driver_name);
 646
 647 out_unlock:
 648         write_unlock_irqrestore(&driver_name_lock, flags);
 649
 650         return count;
 651 }
 652
 653 static const struct file_operations filter_fops = {
 654         .read  = filter_read,
 655         .write = filter_write,
 656         .llseek = default_llseek,
 657 };
 658
 659 static int dma_debug_fs_init(void)
 660 {
 661         dma_debug_dent = debugfs_create_dir("dma-api", NULL);
 662         if (!dma_debug_dent) {
 663                 pr_err("DMA-API: can not create debugfs directory\n");
 664                 return -ENOMEM;
 665         }
 666
 667         global_disable_dent = debugfs_create_bool("disabled", 0444,
 668                         dma_debug_dent,
 669                         &global_disable);
 670         if (!global_disable_dent)
 671                 goto out_err;
 672
 673         error_count_dent = debugfs_create_u32("error_count", 0444,
 674                         dma_debug_dent, &error_count);
 675         if (!error_count_dent)
 676                 goto out_err;
 677
 678         show_all_errors_dent = debugfs_create_u32("all_errors", 0644,
 679                         dma_debug_dent,
 680                         &show_all_errors);
 681         if (!show_all_errors_dent)
 682                 goto out_err;
 683
 684         show_num_errors_dent = debugfs_create_u32("num_errors", 0644,
 685                         dma_debug_dent,
 686                         &show_num_errors);
 687         if (!show_num_errors_dent)
 688                 goto out_err;
 689
 690         num_free_entries_dent = debugfs_create_u32("num_free_entries", 0444,
 691                         dma_debug_dent,
 692                         &num_free_entries);
 693         if (!num_free_entries_dent)
 694                 goto out_err;
 695
 696         min_free_entries_dent = debugfs_create_u32("min_free_entries", 0444,
 697                         dma_debug_dent,
 698                         &min_free_entries);
 699         if (!min_free_entries_dent)
 700                 goto out_err;
 701
 702         filter_dent = debugfs_create_file("driver_filter", 0644,
 703                                           dma_debug_dent, NULL, &filter_fops);
 704         if (!filter_dent)
 705                 goto out_err;
 706
 707         return 0;
 708
 709 out_err:
 710         debugfs_remove_recursive(dma_debug_dent);
 711
 712         return -ENOMEM;
 713 }
 714
 715 static int device_dma_allocations(struct device *dev, struct dma_debug_entry **out_entry)
 716 {
 717         struct dma_debug_entry *entry;
 718         unsigned long flags;
 719         int count = 0, i;
 720
 721         local_irq_save(flags);
 722
 723         for (i = 0; i < HASH_SIZE; ++i) {
 724                 spin_lock(&dma_entry_hash[i].lock);
 725                 list_for_each_entry(entry, &dma_entry_hash[i].list, list) {
 726                         if (entry->dev == dev) {
 727                                 count += 1;
 728                                 *out_entry = entry;
 729                         }
 730                 }
 731                 spin_unlock(&dma_entry_hash[i].lock);
 732         }
 733
 734         local_irq_restore(flags);
 735
 736         return count;
 737 }
 738
 739 static int dma_debug_device_change(struct notifier_block *nb, unsigned long action, void *data)
 740 {
 741         struct device *dev = data;
 742         struct dma_debug_entry *uninitialized_var(entry);
 743         int count;
 744
 745         if (global_disable)
 746                 return 0;
 747
 748         switch (action) {
 749         case BUS_NOTIFY_UNBOUND_DRIVER:
 750                 count = device_dma_allocations(dev, &entry);
 751                 if (count == 0)
 752                         break;
 753                 err_printk(dev, entry, "DMA-API: device driver has pending "
 754                                 "DMA allocations while released from device "
 755                                 "[count=%d]\n"
 756                                 "One of leaked entries details: "
 757                                 "[device address=0x%016llx] [size=%llu bytes] "
 758                                 "[mapped with %s] [mapped as %s]\n",
 759                         count, entry->dev_addr, entry->size,
 760                         dir2name[entry->direction], type2name[entry->type]);
 761                 break;
 762         default:
 763                 break;
 764         }
 765
 766         return 0;
 767 }
 768
 769 void dma_debug_add_bus(struct bus_type *bus)
 770 {
 771         struct notifier_block *nb;
 772
 773         if (global_disable)
 774                 return;
 775
 776         nb = kzalloc(sizeof(struct notifier_block), GFP_KERNEL);
 777         if (nb == NULL) {
 778                 pr_err("dma_debug_add_bus: out of memory\n");
 779                 return;
 780         }
 781
 782         nb->notifier_call = dma_debug_device_change;
 783
 784         bus_register_notifier(bus, nb);
 785 }
 786
 787 /*
 788  * Let the architectures decide how many entries should be preallocated.
 789  */
 790 void dma_debug_init(u32 num_entries)
 791 {
 792         int i;
 793
 794         if (global_disable)
 795                 return;
 796
 797         for (i = 0; i < HASH_SIZE; ++i) {
 798                 INIT_LIST_HEAD(&dma_entry_hash[i].list);
 799                 spin_lock_init(&dma_entry_hash[i].lock);
 800         }
 801
 802         if (dma_debug_fs_init() != 0) {
 803                 pr_err("DMA-API: error creating debugfs entries - disabling\n");
 804                 global_disable = true;
 805
 806                 return;
 807         }
 808
 809         if (req_entries)
 810                 num_entries = req_entries;
 811
 812         if (prealloc_memory(num_entries) != 0) {
 813                 pr_err("DMA-API: debugging out of memory error - disabled\n");
 814                 global_disable = true;
 815
 816                 return;
 817         }
 818
 819         nr_total_entries = num_free_entries;
 820
 821         pr_info("DMA-API: debugging enabled by kernel config\n");
 822 }
 823
 824 static __init int dma_debug_cmdline(char *str)
 825 {
 826         if (!str)
 827                 return -EINVAL;
 828
 829         if (strncmp(str, "off", 3) == 0) {
 830                 pr_info("DMA-API: debugging disabled on kernel command line\n");
 831                 global_disable = true;
 832         }
 833
 834         return 0;
 835 }
 836
 837 static __init int dma_debug_entries_cmdline(char *str)
 838 {
 839         int res;
 840
 841         if (!str)
 842                 return -EINVAL;
 843
 844         res = get_option(&str, &req_entries);
 845
 846         if (!res)
 847                 req_entries = 0;
 848
 849         return 0;
 850 }
 851
 852 __setup("dma_debug=", dma_debug_cmdline);
 853 __setup("dma_debug_entries=", dma_debug_entries_cmdline);
 854
 855 static void check_unmap(struct dma_debug_entry *ref)
 856 {
 857         struct dma_debug_entry *entry;
 858         struct hash_bucket *bucket;
 859         unsigned long flags;
 860
 861         bucket = get_hash_bucket(ref, &flags);
 862         entry = bucket_find_exact(bucket, ref);
 863
 864         if (!entry) {
 865                 /* must drop lock before calling dma_mapping_error */
 866                 put_hash_bucket(bucket, &flags);
 867
 868                 if (dma_mapping_error(ref->dev, ref->dev_addr)) {
 869                         err_printk(ref->dev, NULL,
 870                                    "DMA-API: device driver tries to free an "
 871                                    "invalid DMA memory address\n");
 872                 } else {
 873                         err_printk(ref->dev, NULL,
 874                                    "DMA-API: device driver tries to free DMA "
 875                                    "memory it has not allocated [device "
 876                                    "address=0x%016llx] [size=%llu bytes]\n",
 877                                    ref->dev_addr, ref->size);
 878                 }
 879                 return;
 880         }
 881
 882         if (ref->size != entry->size) {
 883                 err_printk(ref->dev, entry, "DMA-API: device driver frees "
 884                            "DMA memory with different size "
 885                            "[device address=0x%016llx] [map size=%llu bytes] "
 886                            "[unmap size=%llu bytes]\n",
 887                            ref->dev_addr, entry->size, ref->size);
 888         }
 889
 890         if (ref->type != entry->type) {
 891                 err_printk(ref->dev, entry, "DMA-API: device driver frees "
 892                            "DMA memory with wrong function "
 893                            "[device address=0x%016llx] [size=%llu bytes] "
 894                            "[mapped as %s] [unmapped as %s]\n",
 895                            ref->dev_addr, ref->size,
 896                            type2name[entry->type], type2name[ref->type]);
 897         } else if ((entry->type == dma_debug_coherent) &&
 898                    (ref->paddr != entry->paddr)) {
 899                 err_printk(ref->dev, entry, "DMA-API: device driver frees "
 900                            "DMA memory with different CPU address "
 901                            "[device address=0x%016llx] [size=%llu bytes] "
 902                            "[cpu alloc address=0x%016llx] "
 903                            "[cpu free address=0x%016llx]",
 904                            ref->dev_addr, ref->size,
 905                            (unsigned long long)entry->paddr,
 906                            (unsigned long long)ref->paddr);
 907         }
 908
 909         if (ref->sg_call_ents && ref->type == dma_debug_sg &&
 910             ref->sg_call_ents != entry->sg_call_ents) {
 911                 err_printk(ref->dev, entry, "DMA-API: device driver frees "
 912                            "DMA sg list with different entry count "
 913                            "[map count=%d] [unmap count=%d]\n",
 914                            entry->sg_call_ents, ref->sg_call_ents);
 915         }
 916
 917         /*
 918          * This may be no bug in reality - but most implementations of the
 919          * DMA API don't handle this properly, so check for it here
 920          */
 921         if (ref->direction != entry->direction) {
 922                 err_printk(ref->dev, entry, "DMA-API: device driver frees "
 923                            "DMA memory with different direction "
 924                            "[device address=0x%016llx] [size=%llu bytes] "
 925                            "[mapped with %s] [unmapped with %s]\n",
 926                            ref->dev_addr, ref->size,
 927                            dir2name[entry->direction],
 928                            dir2name[ref->direction]);
 929         }
 930
 931         if (entry->map_err_type == MAP_ERR_NOT_CHECKED) {
 932                 err_printk(ref->dev, entry,
 933                            "DMA-API: device driver failed to check map error"
 934                            "[device address=0x%016llx] [size=%llu bytes] "
 935                            "[mapped as %s]",
 936                            ref->dev_addr, ref->size,
 937                            type2name[entry->type]);
 938         }
 939
 940         hash_bucket_del(entry);
 941         dma_entry_free(entry);
 942
 943         put_hash_bucket(bucket, &flags);
 944 }
 945
 946 static void check_for_stack(struct device *dev, void *addr)
 947 {
 948         if (object_is_on_stack(addr))
 949                 err_printk(dev, NULL, "DMA-API: device driver maps memory from"
 950                                 "stack [addr=%p]\n", addr);
 951 }
 952
 953 static inline bool overlap(void *addr, unsigned long len, void *start, void *end)
 954 {
 955         unsigned long a1 = (unsigned long)addr;
 956         unsigned long b1 = a1 + len;
 957         unsigned long a2 = (unsigned long)start;
 958         unsigned long b2 = (unsigned long)end;
 959
 960         return !(b1 <= a2 || a1 >= b2);
 961 }
 962
 963 static void check_for_illegal_area(struct device *dev, void *addr, unsigned long len)
 964 {
 965         if (overlap(addr, len, _text, _etext) ||
 966             overlap(addr, len, __start_rodata, __end_rodata))
 967                 err_printk(dev, NULL, "DMA-API: device driver maps memory from kernel text or rodata [addr=%p] [len=%lu]\n", addr, len);
 968 }
 969
 970 static void check_sync(struct device *dev,
 971                        struct dma_debug_entry *ref,
 972                        bool to_cpu)
 973 {
 974         struct dma_debug_entry *entry;
 975         struct hash_bucket *bucket;
 976         unsigned long flags;
 977
 978         bucket = get_hash_bucket(ref, &flags);
 979
 980         entry = bucket_find_contain(&bucket, ref, &flags);
 981
 982         if (!entry) {
 983                 err_printk(dev, NULL, "DMA-API: device driver tries "
 984                                 "to sync DMA memory it has not allocated "
 985                                 "[device address=0x%016llx] [size=%llu bytes]\n",
 986                                 (unsigned long long)ref->dev_addr, ref->size);
 987                 goto out;
 988         }
 989
 990         if (ref->size > entry->size) {
 991                 err_printk(dev, entry, "DMA-API: device driver syncs"
 992                                 " DMA memory outside allocated range "
 993                                 "[device address=0x%016llx] "
 994                                 "[allocation size=%llu bytes] "
 995                                 "[sync offset+size=%llu]\n",
 996                                 entry->dev_addr, entry->size,
 997                                 ref->size);
 998         }
 999
1000         if (entry->direction == DMA_BIDIRECTIONAL)
1001                 goto out;
1002
1003         if (ref->direction != entry->direction) {
1004                 err_printk(dev, entry, "DMA-API: device driver syncs "
1005                                 "DMA memory with different direction "
1006                                 "[device address=0x%016llx] [size=%llu bytes] "
1007                                 "[mapped with %s] [synced with %s]\n",
1008                                 (unsigned long long)ref->dev_addr, entry->size,
1009                                 dir2name[entry->direction],
1010                                 dir2name[ref->direction]);
1011         }
1012
1013         if (to_cpu && !(entry->direction == DMA_FROM_DEVICE) &&
1014                       !(ref->direction == DMA_TO_DEVICE))
1015                 err_printk(dev, entry, "DMA-API: device driver syncs "
1016                                 "device read-only DMA memory for cpu "
1017                                 "[device address=0x%016llx] [size=%llu bytes] "
1018                                 "[mapped with %s] [synced with %s]\n",
1019                                 (unsigned long long)ref->dev_addr, entry->size,
1020                                 dir2name[entry->direction],
1021                                 dir2name[ref->direction]);
1022
1023         if (!to_cpu && !(entry->direction == DMA_TO_DEVICE) &&
1024                        !(ref->direction == DMA_FROM_DEVICE))
1025                 err_printk(dev, entry, "DMA-API: device driver syncs "
1026                                 "device write-only DMA memory to device "
1027                                 "[device address=0x%016llx] [size=%llu bytes] "
1028                                 "[mapped with %s] [synced with %s]\n",
1029                                 (unsigned long long)ref->dev_addr, entry->size,
1030                                 dir2name[entry->direction],
1031                                 dir2name[ref->direction]);
1032
1033 out:
1034         put_hash_bucket(bucket, &flags);
1035 }
1036
1037 void debug_dma_map_page(struct device *dev, struct page *page, size_t offset,
1038                         size_t size, int direction, dma_addr_t dma_addr,
1039                         bool map_single)
1040 {
1041         struct dma_debug_entry *entry;
1042
1043         if (unlikely(global_disable))
1044                 return;
1045
1046         if (dma_mapping_error(dev, dma_addr))
1047                 return;
1048
1049         entry = dma_entry_alloc();
1050         if (!entry)
1051                 return;
1052
1053         entry->dev       = dev;
1054         entry->type      = dma_debug_page;
1055         entry->paddr     = page_to_phys(page) + offset;
1056         entry->dev_addr  = dma_addr;
1057         entry->size      = size;
1058         entry->direction = direction;
1059         entry->map_err_type = MAP_ERR_NOT_CHECKED;
1060
1061         if (map_single)
1062                 entry->type = dma_debug_single;
1063
1064         if (!PageHighMem(page)) {
1065                 void *addr = page_address(page) + offset;
1066
1067                 check_for_stack(dev, addr);
1068                 check_for_illegal_area(dev, addr, size);
1069         }
1070
1071         add_dma_entry(entry);
1072 }
1073 EXPORT_SYMBOL(debug_dma_map_page);
1074
1075 void debug_dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
1076 {
1077         struct dma_debug_entry ref;
1078         struct dma_debug_entry *entry;
1079         struct hash_bucket *bucket;
1080         unsigned long flags;
1081
1082         if (unlikely(global_disable))
1083                 return;
1084
1085         ref.dev = dev;
1086         ref.dev_addr = dma_addr;
1087         bucket = get_hash_bucket(&ref, &flags);
1088
1089         list_for_each_entry(entry, &bucket->list, list) {
1090                 if (!exact_match(&ref, entry))
1091                         continue;
1092
1093                 /*
1094                  * The same physical address can be mapped multiple
1095                  * times. Without a hardware IOMMU this results in the
1096                  * same device addresses being put into the dma-debug
1097                  * hash multiple times too. This can result in false
1098                  * positives being reported. Therefore we implement a
1099                  * best-fit algorithm here which updates the first entry
1100                  * from the hash which fits the reference value and is
1101                  * not currently listed as being checked.
1102                  */
1103                 if (entry->map_err_type == MAP_ERR_NOT_CHECKED) {
1104                         entry->map_err_type = MAP_ERR_CHECKED;
1105                         break;
1106                 }
1107         }
1108
1109         put_hash_bucket(bucket, &flags);
1110 }
1111 EXPORT_SYMBOL(debug_dma_mapping_error);
1112
1113 void debug_dma_unmap_page(struct device *dev, dma_addr_t addr,
1114                           size_t size, int direction, bool map_single)
1115 {
1116         struct dma_debug_entry ref = {
1117                 .type           = dma_debug_page,
1118                 .dev            = dev,
1119                 .dev_addr       = addr,
1120                 .size           = size,
1121                 .direction      = direction,
1122         };
1123
1124         if (unlikely(global_disable))
1125                 return;
1126
1127         if (map_single)
1128                 ref.type = dma_debug_single;
1129
1130         check_unmap(&ref);
1131 }
1132 EXPORT_SYMBOL(debug_dma_unmap_page);
1133
1134 void debug_dma_map_sg(struct device *dev, struct scatterlist *sg,
1135                       int nents, int mapped_ents, int direction)
1136 {
1137         struct dma_debug_entry *entry;
1138         struct scatterlist *s;
1139         int i;
1140
1141         if (unlikely(global_disable))
1142                 return;
1143
1144         for_each_sg(sg, s, mapped_ents, i) {
1145                 entry = dma_entry_alloc();
1146                 if (!entry)
1147                         return;
1148
1149                 entry->type           = dma_debug_sg;
1150                 entry->dev            = dev;
1151                 entry->paddr          = sg_phys(s);
1152                 entry->size           = sg_dma_len(s);
1153                 entry->dev_addr       = sg_dma_address(s);
1154                 entry->direction      = direction;
1155                 entry->sg_call_ents   = nents;
1156                 entry->sg_mapped_ents = mapped_ents;
1157
1158                 if (!PageHighMem(sg_page(s))) {
1159                         check_for_stack(dev, sg_virt(s));
1160                         check_for_illegal_area(dev, sg_virt(s), sg_dma_len(s));
1161                 }
1162
1163                 add_dma_entry(entry);
1164         }
1165 }
1166 EXPORT_SYMBOL(debug_dma_map_sg);
1167
1168 static int get_nr_mapped_entries(struct device *dev,
1169                                  struct dma_debug_entry *ref)
1170 {
1171         struct dma_debug_entry *entry;
1172         struct hash_bucket *bucket;
1173         unsigned long flags;
1174         int mapped_ents;
1175
1176         bucket       = get_hash_bucket(ref, &flags);
1177         entry        = bucket_find_exact(bucket, ref);
1178         mapped_ents  = 0;
1179
1180         if (entry)
1181                 mapped_ents = entry->sg_mapped_ents;
1182         put_hash_bucket(bucket, &flags);
1183
1184         return mapped_ents;
1185 }
1186
1187 void debug_dma_unmap_sg(struct device *dev, struct scatterlist *sglist,
1188                         int nelems, int dir)
1189 {
1190         struct scatterlist *s;
1191         int mapped_ents = 0, i;
1192
1193         if (unlikely(global_disable))
1194                 return;
1195
1196         for_each_sg(sglist, s, nelems, i) {
1197
1198                 struct dma_debug_entry ref = {
1199                         .type           = dma_debug_sg,
1200                         .dev            = dev,
1201                         .paddr          = sg_phys(s),
1202                         .dev_addr       = sg_dma_address(s),
1203                         .size           = sg_dma_len(s),
1204                         .direction      = dir,
1205                         .sg_call_ents   = nelems,
1206                 };
1207
1208                 if (mapped_ents && i >= mapped_ents)
1209                         break;
1210
1211                 if (!i)
1212                         mapped_ents = get_nr_mapped_entries(dev, &ref);
1213
1214                 check_unmap(&ref);
1215         }
1216 }
1217 EXPORT_SYMBOL(debug_dma_unmap_sg);
1218
1219 void debug_dma_alloc_coherent(struct device *dev, size_t size,
1220                               dma_addr_t dma_addr, void *virt)
1221 {
1222         struct dma_debug_entry *entry;
1223
1224         if (unlikely(global_disable))
1225                 return;
1226
1227         if (unlikely(virt == NULL))
1228                 return;
1229
1230         entry = dma_entry_alloc();
1231         if (!entry)
1232                 return;
1233
1234         entry->type      = dma_debug_coherent;
1235         entry->dev       = dev;
1236         entry->paddr     = virt_to_phys(virt);
1237         entry->size      = size;
1238         entry->dev_addr  = dma_addr;
1239         entry->direction = DMA_BIDIRECTIONAL;
1240
1241         add_dma_entry(entry);
1242 }
1243 EXPORT_SYMBOL(debug_dma_alloc_coherent);
1244
1245 void debug_dma_free_coherent(struct device *dev, size_t size,
1246                          void *virt, dma_addr_t addr)
1247 {
1248         struct dma_debug_entry ref = {
1249                 .type           = dma_debug_coherent,
1250                 .dev            = dev,
1251                 .paddr          = virt_to_phys(virt),
1252                 .dev_addr       = addr,
1253                 .size           = size,
1254                 .direction      = DMA_BIDIRECTIONAL,
1255         };
1256
1257         if (unlikely(global_disable))
1258                 return;
1259
1260         check_unmap(&ref);
1261 }
1262 EXPORT_SYMBOL(debug_dma_free_coherent);
1263
1264 void debug_dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_handle,
1265                                    size_t size, int direction)
1266 {
1267         struct dma_debug_entry ref;
1268
1269         if (unlikely(global_disable))
1270                 return;
1271
1272         ref.type         = dma_debug_single;
1273         ref.dev          = dev;
1274         ref.dev_addr     = dma_handle;
1275         ref.size         = size;
1276         ref.direction    = direction;
1277         ref.sg_call_ents = 0;
1278
1279         check_sync(dev, &ref, true);
1280 }
1281 EXPORT_SYMBOL(debug_dma_sync_single_for_cpu);
1282
1283 void debug_dma_sync_single_for_device(struct device *dev,
1284                                       dma_addr_t dma_handle, size_t size,
1285                                       int direction)
1286 {
1287         struct dma_debug_entry ref;
1288
1289         if (unlikely(global_disable))
1290                 return;
1291
1292         ref.type         = dma_debug_single;
1293         ref.dev          = dev;
1294         ref.dev_addr     = dma_handle;
1295         ref.size         = size;
1296         ref.direction    = direction;
1297         ref.sg_call_ents = 0;
1298
1299         check_sync(dev, &ref, false);
1300 }
1301 EXPORT_SYMBOL(debug_dma_sync_single_for_device);
1302
1303 void debug_dma_sync_single_range_for_cpu(struct device *dev,
1304                                          dma_addr_t dma_handle,
1305                                          unsigned long offset, size_t size,
1306                                          int direction)
1307 {
1308         struct dma_debug_entry ref;
1309
1310         if (unlikely(global_disable))
1311                 return;
1312
1313         ref.type         = dma_debug_single;
1314         ref.dev          = dev;
1315         ref.dev_addr     = dma_handle;
1316         ref.size         = offset + size;
1317         ref.direction    = direction;
1318         ref.sg_call_ents = 0;
1319
1320         check_sync(dev, &ref, true);
1321 }
1322 EXPORT_SYMBOL(debug_dma_sync_single_range_for_cpu);
1323
1324 void debug_dma_sync_single_range_for_device(struct device *dev,
1325                                             dma_addr_t dma_handle,
1326                                             unsigned long offset,
1327                                             size_t size, int direction)
1328 {
1329         struct dma_debug_entry ref;
1330
1331         if (unlikely(global_disable))
1332                 return;
1333
1334         ref.type         = dma_debug_single;
1335         ref.dev          = dev;
1336         ref.dev_addr     = dma_handle;
1337         ref.size         = offset + size;
1338         ref.direction    = direction;
1339         ref.sg_call_ents = 0;
1340
1341         check_sync(dev, &ref, false);
1342 }
1343 EXPORT_SYMBOL(debug_dma_sync_single_range_for_device);
1344
1345 void debug_dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg,
1346                                int nelems, int direction)
1347 {
1348         struct scatterlist *s;
1349         int mapped_ents = 0, i;
1350
1351         if (unlikely(global_disable))
1352                 return;
1353
1354         for_each_sg(sg, s, nelems, i) {
1355
1356                 struct dma_debug_entry ref = {
1357                         .type           = dma_debug_sg,
1358                         .dev            = dev,
1359                         .paddr          = sg_phys(s),
1360                         .dev_addr       = sg_dma_address(s),
1361                         .size           = sg_dma_len(s),
1362                         .direction      = direction,
1363                         .sg_call_ents   = nelems,
1364                 };
1365
1366                 if (!i)
1367                         mapped_ents = get_nr_mapped_entries(dev, &ref);
1368
1369                 if (i >= mapped_ents)
1370                         break;
1371
1372                 check_sync(dev, &ref, true);
1373         }
1374 }
1375 EXPORT_SYMBOL(debug_dma_sync_sg_for_cpu);
1376
1377 void debug_dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
1378                                   int nelems, int direction)
1379 {
1380         struct scatterlist *s;
1381         int mapped_ents = 0, i;
1382
1383         if (unlikely(global_disable))
1384                 return;
1385
1386         for_each_sg(sg, s, nelems, i) {
1387
1388                 struct dma_debug_entry ref = {
1389                         .type           = dma_debug_sg,
1390                         .dev            = dev,
1391                         .paddr          = sg_phys(s),
1392                         .dev_addr       = sg_dma_address(s),
1393                         .size           = sg_dma_len(s),
1394                         .direction      = direction,
1395                         .sg_call_ents   = nelems,
1396                 };
1397                 if (!i)
1398                         mapped_ents = get_nr_mapped_entries(dev, &ref);
1399
1400                 if (i >= mapped_ents)
1401                         break;
1402
1403                 check_sync(dev, &ref, false);
1404         }
1405 }
1406 EXPORT_SYMBOL(debug_dma_sync_sg_for_device);
1407
1408 static int __init dma_debug_driver_setup(char *str)
1409 {
1410         int i;
1411
1412         for (i = 0; i < NAME_MAX_LEN - 1; ++i, ++str) {
1413                 current_driver_name[i] = *str;
1414                 if (*str == 0)
1415                         break;
1416         }
1417
1418         if (current_driver_name[0])
1419                 pr_info("DMA-API: enable driver filter for driver [%s]\n",
1420                         current_driver_name);
1421
1422
1423         return 1;
1424 }
1425 __setup("dma_debug_driver=", dma_debug_driver_setup);