init/initramfs.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/init.h>
   3 #include <linux/async.h>
   4 #include <linux/fs.h>
   5 #include <linux/slab.h>
   6 #include <linux/types.h>
   7 #include <linux/fcntl.h>
   8 #include <linux/delay.h>
   9 #include <linux/string.h>
  10 #include <linux/dirent.h>
  11 #include <linux/syscalls.h>
  12 #include <linux/utime.h>
  13 #include <linux/file.h>
  14 #include <linux/kstrtox.h>
  15 #include <linux/memblock.h>
  16 #include <linux/mm.h>
  17 #include <linux/namei.h>
  18 #include <linux/init_syscalls.h>
  19 #include <linux/task_work.h>
  20 #include <linux/umh.h>
  21
  22 static __initdata bool csum_present;
  23 static __initdata u32 io_csum;
  24
  25 static ssize_t __init xwrite(struct file *file, const unsigned char *p,
  26                 size_t count, loff_t *pos)
  27 {
  28         ssize_t out = 0;
  29
  30         /* sys_write only can write MAX_RW_COUNT aka 2G-4K bytes at most */
  31         while (count) {
  32                 ssize_t rv = kernel_write(file, p, count, pos);
  33
  34                 if (rv < 0) {
  35                         if (rv == -EINTR || rv == -EAGAIN)
  36                                 continue;
  37                         return out ? out : rv;
  38                 } else if (rv == 0)
  39                         break;
  40
  41                 if (csum_present) {
  42                         ssize_t i;
  43
  44                         for (i = 0; i < rv; i++)
  45                                 io_csum += p[i];
  46                 }
  47
  48                 p += rv;
  49                 out += rv;
  50                 count -= rv;
  51         }
  52
  53         return out;
  54 }
  55
  56 static __initdata char *message;
  57 static void __init error(char *x)
  58 {
  59         if (!message)
  60                 message = x;
  61 }
  62
  63 #define panic_show_mem(fmt, ...) \
  64         ({ show_mem(); panic(fmt, ##__VA_ARGS__); })
  65
  66 /* link hash */
  67
  68 #define N_ALIGN(len) ((((len) + 1) & ~3) + 2)
  69
  70 static __initdata struct hash {
  71         int ino, minor, major;
  72         umode_t mode;
  73         struct hash *next;
  74         char name[N_ALIGN(PATH_MAX)];
  75 } *head[32];
  76
  77 static inline int hash(int major, int minor, int ino)
  78 {
  79         unsigned long tmp = ino + minor + (major << 3);
  80         tmp += tmp >> 5;
  81         return tmp & 31;
  82 }
  83
  84 static char __init *find_link(int major, int minor, int ino,
  85                               umode_t mode, char *name)
  86 {
  87         struct hash **p, *q;
  88         for (p = head + hash(major, minor, ino); *p; p = &(*p)->next) {
  89                 if ((*p)->ino != ino)
  90                         continue;
  91                 if ((*p)->minor != minor)
  92                         continue;
  93                 if ((*p)->major != major)
  94                         continue;
  95                 if (((*p)->mode ^ mode) & S_IFMT)
  96                         continue;
  97                 return (*p)->name;
  98         }
  99         q = kmalloc(sizeof(struct hash), GFP_KERNEL);
 100         if (!q)
 101                 panic_show_mem("can't allocate link hash entry");
 102         q->major = major;
 103         q->minor = minor;
 104         q->ino = ino;
 105         q->mode = mode;
 106         strcpy(q->name, name);
 107         q->next = NULL;
 108         *p = q;
 109         return NULL;
 110 }
 111
 112 static void __init free_hash(void)
 113 {
 114         struct hash **p, *q;
 115         for (p = head; p < head + 32; p++) {
 116                 while (*p) {
 117                         q = *p;
 118                         *p = q->next;
 119                         kfree(q);
 120                 }
 121         }
 122 }
 123
 124 #ifdef CONFIG_INITRAMFS_PRESERVE_MTIME
 125 static void __init do_utime(char *filename, time64_t mtime)
 126 {
 127         struct timespec64 t[2] = { { .tv_sec = mtime }, { .tv_sec = mtime } };
 128         init_utimes(filename, t);
 129 }
 130
 131 static void __init do_utime_path(const struct path *path, time64_t mtime)
 132 {
 133         struct timespec64 t[2] = { { .tv_sec = mtime }, { .tv_sec = mtime } };
 134         vfs_utimes(path, t);
 135 }
 136
 137 static __initdata LIST_HEAD(dir_list);
 138 struct dir_entry {
 139         struct list_head list;
 140         time64_t mtime;
 141         char name[];
 142 };
 143
 144 static void __init dir_add(const char *name, time64_t mtime)
 145 {
 146         size_t nlen = strlen(name) + 1;
 147         struct dir_entry *de;
 148
 149         de = kmalloc(sizeof(struct dir_entry) + nlen, GFP_KERNEL);
 150         if (!de)
 151                 panic_show_mem("can't allocate dir_entry buffer");
 152         INIT_LIST_HEAD(&de->list);
 153         strscpy(de->name, name, nlen);
 154         de->mtime = mtime;
 155         list_add(&de->list, &dir_list);
 156 }
 157
 158 static void __init dir_utime(void)
 159 {
 160         struct dir_entry *de, *tmp;
 161         list_for_each_entry_safe(de, tmp, &dir_list, list) {
 162                 list_del(&de->list);
 163                 do_utime(de->name, de->mtime);
 164                 kfree(de);
 165         }
 166 }
 167 #else
 168 static void __init do_utime(char *filename, time64_t mtime) {}
 169 static void __init do_utime_path(const struct path *path, time64_t mtime) {}
 170 static void __init dir_add(const char *name, time64_t mtime) {}
 171 static void __init dir_utime(void) {}
 172 #endif
 173
 174 static __initdata time64_t mtime;
 175
 176 /* cpio header parsing */
 177
 178 static __initdata unsigned long ino, major, minor, nlink;
 179 static __initdata umode_t mode;
 180 static __initdata unsigned long body_len, name_len;
 181 static __initdata uid_t uid;
 182 static __initdata gid_t gid;
 183 static __initdata unsigned rdev;
 184 static __initdata u32 hdr_csum;
 185
 186 static void __init parse_header(char *s)
 187 {
 188         unsigned long parsed[13];
 189         char buf[9];
 190         int i;
 191
 192         buf[8] = '\0';
 193         for (i = 0, s += 6; i < 13; i++, s += 8) {
 194                 memcpy(buf, s, 8);
 195                 parsed[i] = simple_strtoul(buf, NULL, 16);
 196         }
 197         ino = parsed[0];
 198         mode = parsed[1];
 199         uid = parsed[2];
 200         gid = parsed[3];
 201         nlink = parsed[4];
 202         mtime = parsed[5]; /* breaks in y2106 */
 203         body_len = parsed[6];
 204         major = parsed[7];
 205         minor = parsed[8];
 206         rdev = new_encode_dev(MKDEV(parsed[9], parsed[10]));
 207         name_len = parsed[11];
 208         hdr_csum = parsed[12];
 209 }
 210
 211 /* FSM */
 212
 213 static __initdata enum state {
 214         Start,
 215         Collect,
 216         GotHeader,
 217         SkipIt,
 218         GotName,
 219         CopyFile,
 220         GotSymlink,
 221         Reset
 222 } state, next_state;
 223
 224 static __initdata char *victim;
 225 static unsigned long byte_count __initdata;
 226 static __initdata loff_t this_header, next_header;
 227
 228 static inline void __init eat(unsigned n)
 229 {
 230         victim += n;
 231         this_header += n;
 232         byte_count -= n;
 233 }
 234
 235 static __initdata char *collected;
 236 static long remains __initdata;
 237 static __initdata char *collect;
 238
 239 static void __init read_into(char *buf, unsigned size, enum state next)
 240 {
 241         if (byte_count >= size) {
 242                 collected = victim;
 243                 eat(size);
 244                 state = next;
 245         } else {
 246                 collect = collected = buf;
 247                 remains = size;
 248                 next_state = next;
 249                 state = Collect;
 250         }
 251 }
 252
 253 static __initdata char *header_buf, *symlink_buf, *name_buf;
 254
 255 static int __init do_start(void)
 256 {
 257         read_into(header_buf, 110, GotHeader);
 258         return 0;
 259 }
 260
 261 static int __init do_collect(void)
 262 {
 263         unsigned long n = remains;
 264         if (byte_count < n)
 265                 n = byte_count;
 266         memcpy(collect, victim, n);
 267         eat(n);
 268         collect += n;
 269         if ((remains -= n) != 0)
 270                 return 1;
 271         state = next_state;
 272         return 0;
 273 }
 274
 275 static int __init do_header(void)
 276 {
 277         if (!memcmp(collected, "070701", 6)) {
 278                 csum_present = false;
 279         } else if (!memcmp(collected, "070702", 6)) {
 280                 csum_present = true;
 281         } else {
 282                 if (memcmp(collected, "070707", 6) == 0)
 283                         error("incorrect cpio method used: use -H newc option");
 284                 else
 285                         error("no cpio magic");
 286                 return 1;
 287         }
 288         parse_header(collected);
 289         next_header = this_header + N_ALIGN(name_len) + body_len;
 290         next_header = (next_header + 3) & ~3;
 291         state = SkipIt;
 292         if (name_len <= 0 || name_len > PATH_MAX)
 293                 return 0;
 294         if (S_ISLNK(mode)) {
 295                 if (body_len > PATH_MAX)
 296                         return 0;
 297                 collect = collected = symlink_buf;
 298                 remains = N_ALIGN(name_len) + body_len;
 299                 next_state = GotSymlink;
 300                 state = Collect;
 301                 return 0;
 302         }
 303         if (S_ISREG(mode) || !body_len)
 304                 read_into(name_buf, N_ALIGN(name_len), GotName);
 305         return 0;
 306 }
 307
 308 static int __init do_skip(void)
 309 {
 310         if (this_header + byte_count < next_header) {
 311                 eat(byte_count);
 312                 return 1;
 313         } else {
 314                 eat(next_header - this_header);
 315                 state = next_state;
 316                 return 0;
 317         }
 318 }
 319
 320 static int __init do_reset(void)
 321 {
 322         while (byte_count && *victim == '\0')
 323                 eat(1);
 324         if (byte_count && (this_header & 3))
 325                 error("broken padding");
 326         return 1;
 327 }
 328
 329 static void __init clean_path(char *path, umode_t fmode)
 330 {
 331         struct kstat st;
 332
 333         if (!init_stat(path, &st, AT_SYMLINK_NOFOLLOW) &&
 334             (st.mode ^ fmode) & S_IFMT) {
 335                 if (S_ISDIR(st.mode))
 336                         init_rmdir(path);
 337                 else
 338                         init_unlink(path);
 339         }
 340 }
 341
 342 static int __init maybe_link(void)
 343 {
 344         if (nlink >= 2) {
 345                 char *old = find_link(major, minor, ino, mode, collected);
 346                 if (old) {
 347                         clean_path(collected, 0);
 348                         return (init_link(old, collected) < 0) ? -1 : 1;
 349                 }
 350         }
 351         return 0;
 352 }
 353
 354 static __initdata struct file *wfile;
 355 static __initdata loff_t wfile_pos;
 356
 357 static int __init do_name(void)
 358 {
 359         state = SkipIt;
 360         next_state = Reset;
 361         if (strcmp(collected, "TRAILER!!!") == 0) {
 362                 free_hash();
 363                 return 0;
 364         }
 365         clean_path(collected, mode);
 366         if (S_ISREG(mode)) {
 367                 int ml = maybe_link();
 368                 if (ml >= 0) {
 369                         int openflags = O_WRONLY|O_CREAT;
 370                         if (ml != 1)
 371                                 openflags |= O_TRUNC;
 372                         wfile = filp_open(collected, openflags, mode);
 373                         if (IS_ERR(wfile))
 374                                 return 0;
 375                         wfile_pos = 0;
 376                         io_csum = 0;
 377
 378                         vfs_fchown(wfile, uid, gid);
 379                         vfs_fchmod(wfile, mode);
 380                         if (body_len)
 381                                 vfs_truncate(&wfile->f_path, body_len);
 382                         state = CopyFile;
 383                 }
 384         } else if (S_ISDIR(mode)) {
 385                 init_mkdir(collected, mode);
 386                 init_chown(collected, uid, gid, 0);
 387                 init_chmod(collected, mode);
 388                 dir_add(collected, mtime);
 389         } else if (S_ISBLK(mode) || S_ISCHR(mode) ||
 390                    S_ISFIFO(mode) || S_ISSOCK(mode)) {
 391                 if (maybe_link() == 0) {
 392                         init_mknod(collected, mode, rdev);
 393                         init_chown(collected, uid, gid, 0);
 394                         init_chmod(collected, mode);
 395                         do_utime(collected, mtime);
 396                 }
 397         }
 398         return 0;
 399 }
 400
 401 static int __init do_copy(void)
 402 {
 403         if (byte_count >= body_len) {
 404                 if (xwrite(wfile, victim, body_len, &wfile_pos) != body_len)
 405                         error("write error");
 406
 407                 do_utime_path(&wfile->f_path, mtime);
 408                 fput(wfile);
 409                 if (csum_present && io_csum != hdr_csum)
 410                         error("bad data checksum");
 411                 eat(body_len);
 412                 state = SkipIt;
 413                 return 0;
 414         } else {
 415                 if (xwrite(wfile, victim, byte_count, &wfile_pos) != byte_count)
 416                         error("write error");
 417                 body_len -= byte_count;
 418                 eat(byte_count);
 419                 return 1;
 420         }
 421 }
 422
 423 static int __init do_symlink(void)
 424 {
 425         collected[N_ALIGN(name_len) + body_len] = '\0';
 426         clean_path(collected, 0);
 427         init_symlink(collected + N_ALIGN(name_len), collected);
 428         init_chown(collected, uid, gid, AT_SYMLINK_NOFOLLOW);
 429         do_utime(collected, mtime);
 430         state = SkipIt;
 431         next_state = Reset;
 432         return 0;
 433 }
 434
 435 static __initdata int (*actions[])(void) = {
 436         [Start]         = do_start,
 437         [Collect]       = do_collect,
 438         [GotHeader]     = do_header,
 439         [SkipIt]        = do_skip,
 440         [GotName]       = do_name,
 441         [CopyFile]      = do_copy,
 442         [GotSymlink]    = do_symlink,
 443         [Reset]         = do_reset,
 444 };
 445
 446 static long __init write_buffer(char *buf, unsigned long len)
 447 {
 448         byte_count = len;
 449         victim = buf;
 450
 451         while (!actions[state]())
 452                 ;
 453         return len - byte_count;
 454 }
 455
 456 static long __init flush_buffer(void *bufv, unsigned long len)
 457 {
 458         char *buf = bufv;
 459         long written;
 460         long origLen = len;
 461         if (message)
 462                 return -1;
 463         while ((written = write_buffer(buf, len)) < len && !message) {
 464                 char c = buf[written];
 465                 if (c == '0') {
 466                         buf += written;
 467                         len -= written;
 468                         state = Start;
 469                 } else if (c == 0) {
 470                         buf += written;
 471                         len -= written;
 472                         state = Reset;
 473                 } else
 474                         error("junk within compressed archive");
 475         }
 476         return origLen;
 477 }
 478
 479 static unsigned long my_inptr __initdata; /* index of next byte to be processed in inbuf */
 480
 481 #include <linux/decompress/generic.h>
 482
 483 static char * __init unpack_to_rootfs(char *buf, unsigned long len)
 484 {
 485         long written;
 486         decompress_fn decompress;
 487         const char *compress_name;
 488         static __initdata char msg_buf[64];
 489
 490         header_buf = kmalloc(110, GFP_KERNEL);
 491         symlink_buf = kmalloc(PATH_MAX + N_ALIGN(PATH_MAX) + 1, GFP_KERNEL);
 492         name_buf = kmalloc(N_ALIGN(PATH_MAX), GFP_KERNEL);
 493
 494         if (!header_buf || !symlink_buf || !name_buf)
 495                 panic_show_mem("can't allocate buffers");
 496
 497         state = Start;
 498         this_header = 0;
 499         message = NULL;
 500         while (!message && len) {
 501                 loff_t saved_offset = this_header;
 502                 if (*buf == '0' && !(this_header & 3)) {
 503                         state = Start;
 504                         written = write_buffer(buf, len);
 505                         buf += written;
 506                         len -= written;
 507                         continue;
 508                 }
 509                 if (!*buf) {
 510                         buf++;
 511                         len--;
 512                         this_header++;
 513                         continue;
 514                 }
 515                 this_header = 0;
 516                 decompress = decompress_method(buf, len, &compress_name);
 517                 pr_debug("Detected %s compressed data\n", compress_name);
 518                 if (decompress) {
 519                         int res = decompress(buf, len, NULL, flush_buffer, NULL,
 520                                    &my_inptr, error);
 521                         if (res)
 522                                 error("decompressor failed");
 523                 } else if (compress_name) {
 524                         if (!message) {
 525                                 snprintf(msg_buf, sizeof msg_buf,
 526                                          "compression method %s not configured",
 527                                          compress_name);
 528                                 message = msg_buf;
 529                         }
 530                 } else
 531                         error("invalid magic at start of compressed archive");
 532                 if (state != Reset)
 533                         error("junk at the end of compressed archive");
 534                 this_header = saved_offset + my_inptr;
 535                 buf += my_inptr;
 536                 len -= my_inptr;
 537         }
 538         dir_utime();
 539         kfree(name_buf);
 540         kfree(symlink_buf);
 541         kfree(header_buf);
 542         return message;
 543 }
 544
 545 static int __initdata do_retain_initrd;
 546
 547 static int __init retain_initrd_param(char *str)
 548 {
 549         if (*str)
 550                 return 0;
 551         do_retain_initrd = 1;
 552         return 1;
 553 }
 554 __setup("retain_initrd", retain_initrd_param);
 555
 556 #ifdef CONFIG_ARCH_HAS_KEEPINITRD
 557 static int __init keepinitrd_setup(char *__unused)
 558 {
 559         do_retain_initrd = 1;
 560         return 1;
 561 }
 562 __setup("keepinitrd", keepinitrd_setup);
 563 #endif
 564
 565 static bool __initdata initramfs_async = true;
 566 static int __init initramfs_async_setup(char *str)
 567 {
 568         return kstrtobool(str, &initramfs_async) == 0;
 569 }
 570 __setup("initramfs_async=", initramfs_async_setup);
 571
 572 extern char __initramfs_start[];
 573 extern unsigned long __initramfs_size;
 574 #include <linux/initrd.h>
 575 #include <linux/kexec.h>
 576
 577 void __init reserve_initrd_mem(void)
 578 {
 579         phys_addr_t start;
 580         unsigned long size;
 581
 582         /* Ignore the virtul address computed during device tree parsing */
 583         initrd_start = initrd_end = 0;
 584
 585         if (!phys_initrd_size)
 586                 return;
 587         /*
 588          * Round the memory region to page boundaries as per free_initrd_mem()
 589          * This allows us to detect whether the pages overlapping the initrd
 590          * are in use, but more importantly, reserves the entire set of pages
 591          * as we don't want these pages allocated for other purposes.
 592          */
 593         start = round_down(phys_initrd_start, PAGE_SIZE);
 594         size = phys_initrd_size + (phys_initrd_start - start);
 595         size = round_up(size, PAGE_SIZE);
 596
 597         if (!memblock_is_region_memory(start, size)) {
 598                 pr_err("INITRD: 0x%08llx+0x%08lx is not a memory region",
 599                        (u64)start, size);
 600                 goto disable;
 601         }
 602
 603         if (memblock_is_region_reserved(start, size)) {
 604                 pr_err("INITRD: 0x%08llx+0x%08lx overlaps in-use memory region\n",
 605                        (u64)start, size);
 606                 goto disable;
 607         }
 608
 609         memblock_reserve(start, size);
 610         /* Now convert initrd to virtual addresses */
 611         initrd_start = (unsigned long)__va(phys_initrd_start);
 612         initrd_end = initrd_start + phys_initrd_size;
 613         initrd_below_start_ok = 1;
 614
 615         return;
 616 disable:
 617         pr_cont(" - disabling initrd\n");
 618         initrd_start = 0;
 619         initrd_end = 0;
 620 }
 621
 622 void __weak __init free_initrd_mem(unsigned long start, unsigned long end)
 623 {
 624 #ifdef CONFIG_ARCH_KEEP_MEMBLOCK
 625         unsigned long aligned_start = ALIGN_DOWN(start, PAGE_SIZE);
 626         unsigned long aligned_end = ALIGN(end, PAGE_SIZE);
 627
 628         memblock_free((void *)aligned_start, aligned_end - aligned_start);
 629 #endif
 630
 631         free_reserved_area((void *)start, (void *)end, POISON_FREE_INITMEM,
 632                         "initrd");
 633 }
 634
 635 #ifdef CONFIG_KEXEC_CORE
 636 static bool __init kexec_free_initrd(void)
 637 {
 638         unsigned long crashk_start = (unsigned long)__va(crashk_res.start);
 639         unsigned long crashk_end   = (unsigned long)__va(crashk_res.end);
 640
 641         /*
 642          * If the initrd region is overlapped with crashkernel reserved region,
 643          * free only memory that is not part of crashkernel region.
 644          */
 645         if (initrd_start >= crashk_end || initrd_end <= crashk_start)
 646                 return false;
 647
 648         /*
 649          * Initialize initrd memory region since the kexec boot does not do.
 650          */
 651         memset((void *)initrd_start, 0, initrd_end - initrd_start);
 652         if (initrd_start < crashk_start)
 653                 free_initrd_mem(initrd_start, crashk_start);
 654         if (initrd_end > crashk_end)
 655                 free_initrd_mem(crashk_end, initrd_end);
 656         return true;
 657 }
 658 #else
 659 static inline bool kexec_free_initrd(void)
 660 {
 661         return false;
 662 }
 663 #endif /* CONFIG_KEXEC_CORE */
 664
 665 #ifdef CONFIG_BLK_DEV_RAM
 666 static void __init populate_initrd_image(char *err)
 667 {
 668         ssize_t written;
 669         struct file *file;
 670         loff_t pos = 0;
 671
 672         unpack_to_rootfs(__initramfs_start, __initramfs_size);
 673
 674         printk(KERN_INFO "rootfs image is not initramfs (%s); looks like an initrd\n",
 675                         err);
 676         file = filp_open("/initrd.image", O_WRONLY | O_CREAT, 0700);
 677         if (IS_ERR(file))
 678                 return;
 679
 680         written = xwrite(file, (char *)initrd_start, initrd_end - initrd_start,
 681                         &pos);
 682         if (written != initrd_end - initrd_start)
 683                 pr_err("/initrd.image: incomplete write (%zd != %ld)\n",
 684                        written, initrd_end - initrd_start);
 685         fput(file);
 686 }
 687 #endif /* CONFIG_BLK_DEV_RAM */
 688
 689 static void __init do_populate_rootfs(void *unused, async_cookie_t cookie)
 690 {
 691         /* Load the built in initramfs */
 692         char *err = unpack_to_rootfs(__initramfs_start, __initramfs_size);
 693         if (err)
 694                 panic_show_mem("%s", err); /* Failed to decompress INTERNAL initramfs */
 695
 696         if (!initrd_start || IS_ENABLED(CONFIG_INITRAMFS_FORCE))
 697                 goto done;
 698
 699         if (IS_ENABLED(CONFIG_BLK_DEV_RAM))
 700                 printk(KERN_INFO "Trying to unpack rootfs image as initramfs...\n");
 701         else
 702                 printk(KERN_INFO "Unpacking initramfs...\n");
 703
 704         err = unpack_to_rootfs((char *)initrd_start, initrd_end - initrd_start);
 705         if (err) {
 706 #ifdef CONFIG_BLK_DEV_RAM
 707                 populate_initrd_image(err);
 708 #else
 709                 printk(KERN_EMERG "Initramfs unpacking failed: %s\n", err);
 710 #endif
 711         }
 712
 713 done:
 714         /*
 715          * If the initrd region is overlapped with crashkernel reserved region,
 716          * free only memory that is not part of crashkernel region.
 717          */
 718         if (!do_retain_initrd && initrd_start && !kexec_free_initrd())
 719                 free_initrd_mem(initrd_start, initrd_end);
 720         initrd_start = 0;
 721         initrd_end = 0;
 722
 723         flush_delayed_fput();
 724         task_work_run();
 725 }
 726
 727 static ASYNC_DOMAIN_EXCLUSIVE(initramfs_domain);
 728 static async_cookie_t initramfs_cookie;
 729
 730 void wait_for_initramfs(void)
 731 {
 732         if (!initramfs_cookie) {
 733                 /*
 734                  * Something before rootfs_initcall wants to access
 735                  * the filesystem/initramfs. Probably a bug. Make a
 736                  * note, avoid deadlocking the machine, and let the
 737                  * caller's access fail as it used to.
 738                  */
 739                 pr_warn_once("wait_for_initramfs() called before rootfs_initcalls\n");
 740                 return;
 741         }
 742         async_synchronize_cookie_domain(initramfs_cookie + 1, &initramfs_domain);
 743 }
 744 EXPORT_SYMBOL_GPL(wait_for_initramfs);
 745
 746 static int __init populate_rootfs(void)
 747 {
 748         initramfs_cookie = async_schedule_domain(do_populate_rootfs, NULL,
 749                                                  &initramfs_domain);
 750         usermodehelper_enable();
 751         if (!initramfs_async)
 752                 wait_for_initramfs();
 753         return 0;
 754 }
 755 rootfs_initcall(populate_rootfs);