linux/fs/proc/generic.c
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   1/*
   2 * proc/fs/generic.c --- generic routines for the proc-fs
   3 *
   4 * This file contains generic proc-fs routines for handling
   5 * directories and files.
   6 * 
   7 * Copyright (C) 1991, 1992 Linus Torvalds.
   8 * Copyright (C) 1997 Theodore Ts'o
   9 */
  10
  11#include <linux/errno.h>
  12#include <linux/time.h>
  13#include <linux/proc_fs.h>
  14#include <linux/stat.h>
  15#include <linux/mm.h>
  16#include <linux/module.h>
  17#include <linux/slab.h>
  18#include <linux/mount.h>
  19#include <linux/init.h>
  20#include <linux/idr.h>
  21#include <linux/namei.h>
  22#include <linux/bitops.h>
  23#include <linux/spinlock.h>
  24#include <linux/completion.h>
  25#include <asm/uaccess.h>
  26
  27#include "internal.h"
  28
  29DEFINE_SPINLOCK(proc_subdir_lock);
  30
  31static int proc_match(unsigned int len, const char *name, struct proc_dir_entry *de)
  32{
  33        if (de->namelen != len)
  34                return 0;
  35        return !memcmp(name, de->name, len);
  36}
  37
  38/* buffer size is one page but our output routines use some slack for overruns */
  39#define PROC_BLOCK_SIZE (PAGE_SIZE - 1024)
  40
  41static ssize_t
  42__proc_file_read(struct file *file, char __user *buf, size_t nbytes,
  43               loff_t *ppos)
  44{
  45        struct inode * inode = file->f_path.dentry->d_inode;
  46        char    *page;
  47        ssize_t retval=0;
  48        int     eof=0;
  49        ssize_t n, count;
  50        char    *start;
  51        struct proc_dir_entry * dp;
  52        unsigned long long pos;
  53
  54        /*
  55         * Gaah, please just use "seq_file" instead. The legacy /proc
  56         * interfaces cut loff_t down to off_t for reads, and ignore
  57         * the offset entirely for writes..
  58         */
  59        pos = *ppos;
  60        if (pos > MAX_NON_LFS)
  61                return 0;
  62        if (nbytes > MAX_NON_LFS - pos)
  63                nbytes = MAX_NON_LFS - pos;
  64
  65        dp = PDE(inode);
  66        if (!(page = (char*) __get_free_page(GFP_TEMPORARY)))
  67                return -ENOMEM;
  68
  69        while ((nbytes > 0) && !eof) {
  70                count = min_t(size_t, PROC_BLOCK_SIZE, nbytes);
  71
  72                start = NULL;
  73                if (dp->read_proc) {
  74                        /*
  75                         * How to be a proc read function
  76                         * ------------------------------
  77                         * Prototype:
  78                         *    int f(char *buffer, char **start, off_t offset,
  79                         *          int count, int *peof, void *dat)
  80                         *
  81                         * Assume that the buffer is "count" bytes in size.
  82                         *
  83                         * If you know you have supplied all the data you
  84                         * have, set *peof.
  85                         *
  86                         * You have three ways to return data:
  87                         * 0) Leave *start = NULL.  (This is the default.)
  88                         *    Put the data of the requested offset at that
  89                         *    offset within the buffer.  Return the number (n)
  90                         *    of bytes there are from the beginning of the
  91                         *    buffer up to the last byte of data.  If the
  92                         *    number of supplied bytes (= n - offset) is 
  93                         *    greater than zero and you didn't signal eof
  94                         *    and the reader is prepared to take more data
  95                         *    you will be called again with the requested
  96                         *    offset advanced by the number of bytes 
  97                         *    absorbed.  This interface is useful for files
  98                         *    no larger than the buffer.
  99                         * 1) Set *start = an unsigned long value less than
 100                         *    the buffer address but greater than zero.
 101                         *    Put the data of the requested offset at the
 102                         *    beginning of the buffer.  Return the number of
 103                         *    bytes of data placed there.  If this number is
 104                         *    greater than zero and you didn't signal eof
 105                         *    and the reader is prepared to take more data
 106                         *    you will be called again with the requested
 107                         *    offset advanced by *start.  This interface is
 108                         *    useful when you have a large file consisting
 109                         *    of a series of blocks which you want to count
 110                         *    and return as wholes.
 111                         *    (Hack by Paul.Russell@rustcorp.com.au)
 112                         * 2) Set *start = an address within the buffer.
 113                         *    Put the data of the requested offset at *start.
 114                         *    Return the number of bytes of data placed there.
 115                         *    If this number is greater than zero and you
 116                         *    didn't signal eof and the reader is prepared to
 117                         *    take more data you will be called again with the
 118                         *    requested offset advanced by the number of bytes
 119                         *    absorbed.
 120                         */
 121                        n = dp->read_proc(page, &start, *ppos,
 122                                          count, &eof, dp->data);
 123                } else
 124                        break;
 125
 126                if (n == 0)   /* end of file */
 127                        break;
 128                if (n < 0) {  /* error */
 129                        if (retval == 0)
 130                                retval = n;
 131                        break;
 132                }
 133
 134                if (start == NULL) {
 135                        if (n > PAGE_SIZE) {
 136                                printk(KERN_ERR
 137                                       "proc_file_read: Apparent buffer overflow!\n");
 138                                n = PAGE_SIZE;
 139                        }
 140                        n -= *ppos;
 141                        if (n <= 0)
 142                                break;
 143                        if (n > count)
 144                                n = count;
 145                        start = page + *ppos;
 146                } else if (start < page) {
 147                        if (n > PAGE_SIZE) {
 148                                printk(KERN_ERR
 149                                       "proc_file_read: Apparent buffer overflow!\n");
 150                                n = PAGE_SIZE;
 151                        }
 152                        if (n > count) {
 153                                /*
 154                                 * Don't reduce n because doing so might
 155                                 * cut off part of a data block.
 156                                 */
 157                                printk(KERN_WARNING
 158                                       "proc_file_read: Read count exceeded\n");
 159                        }
 160                } else /* start >= page */ {
 161                        unsigned long startoff = (unsigned long)(start - page);
 162                        if (n > (PAGE_SIZE - startoff)) {
 163                                printk(KERN_ERR
 164                                       "proc_file_read: Apparent buffer overflow!\n");
 165                                n = PAGE_SIZE - startoff;
 166                        }
 167                        if (n > count)
 168                                n = count;
 169                }
 170                
 171                n -= copy_to_user(buf, start < page ? page : start, n);
 172                if (n == 0) {
 173                        if (retval == 0)
 174                                retval = -EFAULT;
 175                        break;
 176                }
 177
 178                *ppos += start < page ? (unsigned long)start : n;
 179                nbytes -= n;
 180                buf += n;
 181                retval += n;
 182        }
 183        free_page((unsigned long) page);
 184        return retval;
 185}
 186
 187static ssize_t
 188proc_file_read(struct file *file, char __user *buf, size_t nbytes,
 189               loff_t *ppos)
 190{
 191        struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
 192        ssize_t rv = -EIO;
 193
 194        spin_lock(&pde->pde_unload_lock);
 195        if (!pde->proc_fops) {
 196                spin_unlock(&pde->pde_unload_lock);
 197                return rv;
 198        }
 199        pde->pde_users++;
 200        spin_unlock(&pde->pde_unload_lock);
 201
 202        rv = __proc_file_read(file, buf, nbytes, ppos);
 203
 204        pde_users_dec(pde);
 205        return rv;
 206}
 207
 208static ssize_t
 209proc_file_write(struct file *file, const char __user *buffer,
 210                size_t count, loff_t *ppos)
 211{
 212        struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
 213        ssize_t rv = -EIO;
 214
 215        if (pde->write_proc) {
 216                spin_lock(&pde->pde_unload_lock);
 217                if (!pde->proc_fops) {
 218                        spin_unlock(&pde->pde_unload_lock);
 219                        return rv;
 220                }
 221                pde->pde_users++;
 222                spin_unlock(&pde->pde_unload_lock);
 223
 224                /* FIXME: does this routine need ppos?  probably... */
 225                rv = pde->write_proc(file, buffer, count, pde->data);
 226                pde_users_dec(pde);
 227        }
 228        return rv;
 229}
 230
 231
 232static loff_t
 233proc_file_lseek(struct file *file, loff_t offset, int orig)
 234{
 235        loff_t retval = -EINVAL;
 236        switch (orig) {
 237        case 1:
 238                offset += file->f_pos;
 239        /* fallthrough */
 240        case 0:
 241                if (offset < 0 || offset > MAX_NON_LFS)
 242                        break;
 243                file->f_pos = retval = offset;
 244        }
 245        return retval;
 246}
 247
 248static const struct file_operations proc_file_operations = {
 249        .llseek         = proc_file_lseek,
 250        .read           = proc_file_read,
 251        .write          = proc_file_write,
 252};
 253
 254static int proc_notify_change(struct dentry *dentry, struct iattr *iattr)
 255{
 256        struct inode *inode = dentry->d_inode;
 257        struct proc_dir_entry *de = PDE(inode);
 258        int error;
 259
 260        error = inode_change_ok(inode, iattr);
 261        if (error)
 262                return error;
 263
 264        if ((iattr->ia_valid & ATTR_SIZE) &&
 265            iattr->ia_size != i_size_read(inode)) {
 266                error = vmtruncate(inode, iattr->ia_size);
 267                if (error)
 268                        return error;
 269        }
 270
 271        setattr_copy(inode, iattr);
 272        mark_inode_dirty(inode);
 273        
 274        de->uid = inode->i_uid;
 275        de->gid = inode->i_gid;
 276        de->mode = inode->i_mode;
 277        return 0;
 278}
 279
 280static int proc_getattr(struct vfsmount *mnt, struct dentry *dentry,
 281                        struct kstat *stat)
 282{
 283        struct inode *inode = dentry->d_inode;
 284        struct proc_dir_entry *de = PROC_I(inode)->pde;
 285        if (de && de->nlink)
 286                set_nlink(inode, de->nlink);
 287
 288        generic_fillattr(inode, stat);
 289        return 0;
 290}
 291
 292static const struct inode_operations proc_file_inode_operations = {
 293        .setattr        = proc_notify_change,
 294};
 295
 296/*
 297 * This function parses a name such as "tty/driver/serial", and
 298 * returns the struct proc_dir_entry for "/proc/tty/driver", and
 299 * returns "serial" in residual.
 300 */
 301static int __xlate_proc_name(const char *name, struct proc_dir_entry **ret,
 302                             const char **residual)
 303{
 304        const char              *cp = name, *next;
 305        struct proc_dir_entry   *de;
 306        unsigned int            len;
 307
 308        de = *ret;
 309        if (!de)
 310                de = &proc_root;
 311
 312        while (1) {
 313                next = strchr(cp, '/');
 314                if (!next)
 315                        break;
 316
 317                len = next - cp;
 318                for (de = de->subdir; de ; de = de->next) {
 319                        if (proc_match(len, cp, de))
 320                                break;
 321                }
 322                if (!de) {
 323                        WARN(1, "name '%s'\n", name);
 324                        return -ENOENT;
 325                }
 326                cp += len + 1;
 327        }
 328        *residual = cp;
 329        *ret = de;
 330        return 0;
 331}
 332
 333static int xlate_proc_name(const char *name, struct proc_dir_entry **ret,
 334                           const char **residual)
 335{
 336        int rv;
 337
 338        spin_lock(&proc_subdir_lock);
 339        rv = __xlate_proc_name(name, ret, residual);
 340        spin_unlock(&proc_subdir_lock);
 341        return rv;
 342}
 343
 344static DEFINE_IDA(proc_inum_ida);
 345static DEFINE_SPINLOCK(proc_inum_lock); /* protects the above */
 346
 347#define PROC_DYNAMIC_FIRST 0xF0000000U
 348
 349/*
 350 * Return an inode number between PROC_DYNAMIC_FIRST and
 351 * 0xffffffff, or zero on failure.
 352 */
 353static unsigned int get_inode_number(void)
 354{
 355        unsigned int i;
 356        int error;
 357
 358retry:
 359        if (ida_pre_get(&proc_inum_ida, GFP_KERNEL) == 0)
 360                return 0;
 361
 362        spin_lock(&proc_inum_lock);
 363        error = ida_get_new(&proc_inum_ida, &i);
 364        spin_unlock(&proc_inum_lock);
 365        if (error == -EAGAIN)
 366                goto retry;
 367        else if (error)
 368                return 0;
 369
 370        if (i > UINT_MAX - PROC_DYNAMIC_FIRST) {
 371                spin_lock(&proc_inum_lock);
 372                ida_remove(&proc_inum_ida, i);
 373                spin_unlock(&proc_inum_lock);
 374                return 0;
 375        }
 376        return PROC_DYNAMIC_FIRST + i;
 377}
 378
 379static void release_inode_number(unsigned int inum)
 380{
 381        spin_lock(&proc_inum_lock);
 382        ida_remove(&proc_inum_ida, inum - PROC_DYNAMIC_FIRST);
 383        spin_unlock(&proc_inum_lock);
 384}
 385
 386static void *proc_follow_link(struct dentry *dentry, struct nameidata *nd)
 387{
 388        nd_set_link(nd, PDE(dentry->d_inode)->data);
 389        return NULL;
 390}
 391
 392static const struct inode_operations proc_link_inode_operations = {
 393        .readlink       = generic_readlink,
 394        .follow_link    = proc_follow_link,
 395};
 396
 397/*
 398 * As some entries in /proc are volatile, we want to 
 399 * get rid of unused dentries.  This could be made 
 400 * smarter: we could keep a "volatile" flag in the 
 401 * inode to indicate which ones to keep.
 402 */
 403static int proc_delete_dentry(const struct dentry * dentry)
 404{
 405        return 1;
 406}
 407
 408static const struct dentry_operations proc_dentry_operations =
 409{
 410        .d_delete       = proc_delete_dentry,
 411};
 412
 413/*
 414 * Don't create negative dentries here, return -ENOENT by hand
 415 * instead.
 416 */
 417struct dentry *proc_lookup_de(struct proc_dir_entry *de, struct inode *dir,
 418                struct dentry *dentry)
 419{
 420        struct inode *inode = NULL;
 421        int error = -ENOENT;
 422
 423        spin_lock(&proc_subdir_lock);
 424        for (de = de->subdir; de ; de = de->next) {
 425                if (de->namelen != dentry->d_name.len)
 426                        continue;
 427                if (!memcmp(dentry->d_name.name, de->name, de->namelen)) {
 428                        pde_get(de);
 429                        spin_unlock(&proc_subdir_lock);
 430                        error = -EINVAL;
 431                        inode = proc_get_inode(dir->i_sb, de);
 432                        goto out_unlock;
 433                }
 434        }
 435        spin_unlock(&proc_subdir_lock);
 436out_unlock:
 437
 438        if (inode) {
 439                d_set_d_op(dentry, &proc_dentry_operations);
 440                d_add(dentry, inode);
 441                return NULL;
 442        }
 443        if (de)
 444                pde_put(de);
 445        return ERR_PTR(error);
 446}
 447
 448struct dentry *proc_lookup(struct inode *dir, struct dentry *dentry,
 449                struct nameidata *nd)
 450{
 451        return proc_lookup_de(PDE(dir), dir, dentry);
 452}
 453
 454/*
 455 * This returns non-zero if at EOF, so that the /proc
 456 * root directory can use this and check if it should
 457 * continue with the <pid> entries..
 458 *
 459 * Note that the VFS-layer doesn't care about the return
 460 * value of the readdir() call, as long as it's non-negative
 461 * for success..
 462 */
 463int proc_readdir_de(struct proc_dir_entry *de, struct file *filp, void *dirent,
 464                filldir_t filldir)
 465{
 466        unsigned int ino;
 467        int i;
 468        struct inode *inode = filp->f_path.dentry->d_inode;
 469        int ret = 0;
 470
 471        ino = inode->i_ino;
 472        i = filp->f_pos;
 473        switch (i) {
 474                case 0:
 475                        if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
 476                                goto out;
 477                        i++;
 478                        filp->f_pos++;
 479                        /* fall through */
 480                case 1:
 481                        if (filldir(dirent, "..", 2, i,
 482                                    parent_ino(filp->f_path.dentry),
 483                                    DT_DIR) < 0)
 484                                goto out;
 485                        i++;
 486                        filp->f_pos++;
 487                        /* fall through */
 488                default:
 489                        spin_lock(&proc_subdir_lock);
 490                        de = de->subdir;
 491                        i -= 2;
 492                        for (;;) {
 493                                if (!de) {
 494                                        ret = 1;
 495                                        spin_unlock(&proc_subdir_lock);
 496                                        goto out;
 497                                }
 498                                if (!i)
 499                                        break;
 500                                de = de->next;
 501                                i--;
 502                        }
 503
 504                        do {
 505                                struct proc_dir_entry *next;
 506
 507                                /* filldir passes info to user space */
 508                                pde_get(de);
 509                                spin_unlock(&proc_subdir_lock);
 510                                if (filldir(dirent, de->name, de->namelen, filp->f_pos,
 511                                            de->low_ino, de->mode >> 12) < 0) {
 512                                        pde_put(de);
 513                                        goto out;
 514                                }
 515                                spin_lock(&proc_subdir_lock);
 516                                filp->f_pos++;
 517                                next = de->next;
 518                                pde_put(de);
 519                                de = next;
 520                        } while (de);
 521                        spin_unlock(&proc_subdir_lock);
 522        }
 523        ret = 1;
 524out:
 525        return ret;     
 526}
 527
 528int proc_readdir(struct file *filp, void *dirent, filldir_t filldir)
 529{
 530        struct inode *inode = filp->f_path.dentry->d_inode;
 531
 532        return proc_readdir_de(PDE(inode), filp, dirent, filldir);
 533}
 534
 535/*
 536 * These are the generic /proc directory operations. They
 537 * use the in-memory "struct proc_dir_entry" tree to parse
 538 * the /proc directory.
 539 */
 540static const struct file_operations proc_dir_operations = {
 541        .llseek                 = generic_file_llseek,
 542        .read                   = generic_read_dir,
 543        .readdir                = proc_readdir,
 544};
 545
 546/*
 547 * proc directories can do almost nothing..
 548 */
 549static const struct inode_operations proc_dir_inode_operations = {
 550        .lookup         = proc_lookup,
 551        .getattr        = proc_getattr,
 552        .setattr        = proc_notify_change,
 553};
 554
 555static int proc_register(struct proc_dir_entry * dir, struct proc_dir_entry * dp)
 556{
 557        unsigned int i;
 558        struct proc_dir_entry *tmp;
 559        
 560        i = get_inode_number();
 561        if (i == 0)
 562                return -EAGAIN;
 563        dp->low_ino = i;
 564
 565        if (S_ISDIR(dp->mode)) {
 566                if (dp->proc_iops == NULL) {
 567                        dp->proc_fops = &proc_dir_operations;
 568                        dp->proc_iops = &proc_dir_inode_operations;
 569                }
 570                dir->nlink++;
 571        } else if (S_ISLNK(dp->mode)) {
 572                if (dp->proc_iops == NULL)
 573                        dp->proc_iops = &proc_link_inode_operations;
 574        } else if (S_ISREG(dp->mode)) {
 575                if (dp->proc_fops == NULL)
 576                        dp->proc_fops = &proc_file_operations;
 577                if (dp->proc_iops == NULL)
 578                        dp->proc_iops = &proc_file_inode_operations;
 579        }
 580
 581        spin_lock(&proc_subdir_lock);
 582
 583        for (tmp = dir->subdir; tmp; tmp = tmp->next)
 584                if (strcmp(tmp->name, dp->name) == 0) {
 585                        WARN(1, KERN_WARNING "proc_dir_entry '%s/%s' already registered\n",
 586                                dir->name, dp->name);
 587                        break;
 588                }
 589
 590        dp->next = dir->subdir;
 591        dp->parent = dir;
 592        dir->subdir = dp;
 593        spin_unlock(&proc_subdir_lock);
 594
 595        return 0;
 596}
 597
 598static struct proc_dir_entry *__proc_create(struct proc_dir_entry **parent,
 599                                          const char *name,
 600                                          umode_t mode,
 601                                          nlink_t nlink)
 602{
 603        struct proc_dir_entry *ent = NULL;
 604        const char *fn = name;
 605        unsigned int len;
 606
 607        /* make sure name is valid */
 608        if (!name || !strlen(name)) goto out;
 609
 610        if (xlate_proc_name(name, parent, &fn) != 0)
 611                goto out;
 612
 613        /* At this point there must not be any '/' characters beyond *fn */
 614        if (strchr(fn, '/'))
 615                goto out;
 616
 617        len = strlen(fn);
 618
 619        ent = kmalloc(sizeof(struct proc_dir_entry) + len + 1, GFP_KERNEL);
 620        if (!ent) goto out;
 621
 622        memset(ent, 0, sizeof(struct proc_dir_entry));
 623        memcpy(ent->name, fn, len + 1);
 624        ent->namelen = len;
 625        ent->mode = mode;
 626        ent->nlink = nlink;
 627        atomic_set(&ent->count, 1);
 628        ent->pde_users = 0;
 629        spin_lock_init(&ent->pde_unload_lock);
 630        ent->pde_unload_completion = NULL;
 631        INIT_LIST_HEAD(&ent->pde_openers);
 632 out:
 633        return ent;
 634}
 635
 636struct proc_dir_entry *proc_symlink(const char *name,
 637                struct proc_dir_entry *parent, const char *dest)
 638{
 639        struct proc_dir_entry *ent;
 640
 641        ent = __proc_create(&parent, name,
 642                          (S_IFLNK | S_IRUGO | S_IWUGO | S_IXUGO),1);
 643
 644        if (ent) {
 645                ent->data = kmalloc((ent->size=strlen(dest))+1, GFP_KERNEL);
 646                if (ent->data) {
 647                        strcpy((char*)ent->data,dest);
 648                        if (proc_register(parent, ent) < 0) {
 649                                kfree(ent->data);
 650                                kfree(ent);
 651                                ent = NULL;
 652                        }
 653                } else {
 654                        kfree(ent);
 655                        ent = NULL;
 656                }
 657        }
 658        return ent;
 659}
 660EXPORT_SYMBOL(proc_symlink);
 661
 662struct proc_dir_entry *proc_mkdir_mode(const char *name, umode_t mode,
 663                struct proc_dir_entry *parent)
 664{
 665        struct proc_dir_entry *ent;
 666
 667        ent = __proc_create(&parent, name, S_IFDIR | mode, 2);
 668        if (ent) {
 669                if (proc_register(parent, ent) < 0) {
 670                        kfree(ent);
 671                        ent = NULL;
 672                }
 673        }
 674        return ent;
 675}
 676EXPORT_SYMBOL(proc_mkdir_mode);
 677
 678struct proc_dir_entry *proc_net_mkdir(struct net *net, const char *name,
 679                struct proc_dir_entry *parent)
 680{
 681        struct proc_dir_entry *ent;
 682
 683        ent = __proc_create(&parent, name, S_IFDIR | S_IRUGO | S_IXUGO, 2);
 684        if (ent) {
 685                ent->data = net;
 686                if (proc_register(parent, ent) < 0) {
 687                        kfree(ent);
 688                        ent = NULL;
 689                }
 690        }
 691        return ent;
 692}
 693EXPORT_SYMBOL_GPL(proc_net_mkdir);
 694
 695struct proc_dir_entry *proc_mkdir(const char *name,
 696                struct proc_dir_entry *parent)
 697{
 698        return proc_mkdir_mode(name, S_IRUGO | S_IXUGO, parent);
 699}
 700EXPORT_SYMBOL(proc_mkdir);
 701
 702struct proc_dir_entry *create_proc_entry(const char *name, umode_t mode,
 703                                         struct proc_dir_entry *parent)
 704{
 705        struct proc_dir_entry *ent;
 706        nlink_t nlink;
 707
 708        if (S_ISDIR(mode)) {
 709                if ((mode & S_IALLUGO) == 0)
 710                        mode |= S_IRUGO | S_IXUGO;
 711                nlink = 2;
 712        } else {
 713                if ((mode & S_IFMT) == 0)
 714                        mode |= S_IFREG;
 715                if ((mode & S_IALLUGO) == 0)
 716                        mode |= S_IRUGO;
 717                nlink = 1;
 718        }
 719
 720        ent = __proc_create(&parent, name, mode, nlink);
 721        if (ent) {
 722                if (proc_register(parent, ent) < 0) {
 723                        kfree(ent);
 724                        ent = NULL;
 725                }
 726        }
 727        return ent;
 728}
 729EXPORT_SYMBOL(create_proc_entry);
 730
 731struct proc_dir_entry *proc_create_data(const char *name, umode_t mode,
 732                                        struct proc_dir_entry *parent,
 733                                        const struct file_operations *proc_fops,
 734                                        void *data)
 735{
 736        struct proc_dir_entry *pde;
 737        nlink_t nlink;
 738
 739        if (S_ISDIR(mode)) {
 740                if ((mode & S_IALLUGO) == 0)
 741                        mode |= S_IRUGO | S_IXUGO;
 742                nlink = 2;
 743        } else {
 744                if ((mode & S_IFMT) == 0)
 745                        mode |= S_IFREG;
 746                if ((mode & S_IALLUGO) == 0)
 747                        mode |= S_IRUGO;
 748                nlink = 1;
 749        }
 750
 751        pde = __proc_create(&parent, name, mode, nlink);
 752        if (!pde)
 753                goto out;
 754        pde->proc_fops = proc_fops;
 755        pde->data = data;
 756        if (proc_register(parent, pde) < 0)
 757                goto out_free;
 758        return pde;
 759out_free:
 760        kfree(pde);
 761out:
 762        return NULL;
 763}
 764EXPORT_SYMBOL(proc_create_data);
 765
 766static void free_proc_entry(struct proc_dir_entry *de)
 767{
 768        release_inode_number(de->low_ino);
 769
 770        if (S_ISLNK(de->mode))
 771                kfree(de->data);
 772        kfree(de);
 773}
 774
 775void pde_put(struct proc_dir_entry *pde)
 776{
 777        if (atomic_dec_and_test(&pde->count))
 778                free_proc_entry(pde);
 779}
 780
 781/*
 782 * Remove a /proc entry and free it if it's not currently in use.
 783 */
 784void remove_proc_entry(const char *name, struct proc_dir_entry *parent)
 785{
 786        struct proc_dir_entry **p;
 787        struct proc_dir_entry *de = NULL;
 788        const char *fn = name;
 789        unsigned int len;
 790
 791        spin_lock(&proc_subdir_lock);
 792        if (__xlate_proc_name(name, &parent, &fn) != 0) {
 793                spin_unlock(&proc_subdir_lock);
 794                return;
 795        }
 796        len = strlen(fn);
 797
 798        for (p = &parent->subdir; *p; p=&(*p)->next ) {
 799                if (proc_match(len, fn, *p)) {
 800                        de = *p;
 801                        *p = de->next;
 802                        de->next = NULL;
 803                        break;
 804                }
 805        }
 806        spin_unlock(&proc_subdir_lock);
 807        if (!de) {
 808                WARN(1, "name '%s'\n", name);
 809                return;
 810        }
 811
 812        spin_lock(&de->pde_unload_lock);
 813        /*
 814         * Stop accepting new callers into module. If you're
 815         * dynamically allocating ->proc_fops, save a pointer somewhere.
 816         */
 817        de->proc_fops = NULL;
 818        /* Wait until all existing callers into module are done. */
 819        if (de->pde_users > 0) {
 820                DECLARE_COMPLETION_ONSTACK(c);
 821
 822                if (!de->pde_unload_completion)
 823                        de->pde_unload_completion = &c;
 824
 825                spin_unlock(&de->pde_unload_lock);
 826
 827                wait_for_completion(de->pde_unload_completion);
 828
 829                spin_lock(&de->pde_unload_lock);
 830        }
 831
 832        while (!list_empty(&de->pde_openers)) {
 833                struct pde_opener *pdeo;
 834
 835                pdeo = list_first_entry(&de->pde_openers, struct pde_opener, lh);
 836                list_del(&pdeo->lh);
 837                spin_unlock(&de->pde_unload_lock);
 838                pdeo->release(pdeo->inode, pdeo->file);
 839                kfree(pdeo);
 840                spin_lock(&de->pde_unload_lock);
 841        }
 842        spin_unlock(&de->pde_unload_lock);
 843
 844        if (S_ISDIR(de->mode))
 845                parent->nlink--;
 846        de->nlink = 0;
 847        WARN(de->subdir, KERN_WARNING "%s: removing non-empty directory "
 848                        "'%s/%s', leaking at least '%s'\n", __func__,
 849                        de->parent->name, de->name, de->subdir->name);
 850        pde_put(de);
 851}
 852EXPORT_SYMBOL(remove_proc_entry);
 853
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