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base.c

/*
 *  linux/fs/proc/base.c
 *
 *  Copyright (C) 1991, 1992 Linus Torvalds
 *
 *  proc base directory handling functions
 *
 *  1999, Al Viro. Rewritten. Now it covers the whole per-process part.
 *  Instead of using magical inumbers to determine the kind of object
 *  we allocate and fill in-core inodes upon lookup. They don't even
 *  go into icache. We cache the reference to task_struct upon lookup too.
 *  Eventually it should become a filesystem in its own. We don't use the
 *  rest of procfs anymore.
 *
 *
 *  Changelog:
 *  17-Jan-2005
 *  Allan Bezerra
 *  Bruna Moreira <bruna.moreira@indt.org.br>
 *  Edjard Mota <edjard.mota@indt.org.br>
 *  Ilias Biris <ilias.biris@indt.org.br>
 *  Mauricio Lin <mauricio.lin@indt.org.br>
 *
 *  Embedded Linux Lab - 10LE Instituto Nokia de Tecnologia - INdT
 *
 *  A new process specific entry (smaps) included in /proc. It shows the
 *  size of rss for each memory area. The maps entry lacks information
 *  about physical memory size (rss) for each mapped file, i.e.,
 *  rss information for executables and library files.
 *  This additional information is useful for any tools that need to know
 *  about physical memory consumption for a process specific library.
 *
 *  Changelog:
 *  21-Feb-2005
 *  Embedded Linux Lab - 10LE Instituto Nokia de Tecnologia - INdT
 *  Pud inclusion in the page table walking.
 *
 *  ChangeLog:
 *  10-Mar-2005
 *  10LE Instituto Nokia de Tecnologia - INdT:
 *  A better way to walks through the page table as suggested by Hugh Dickins.
 *
 *  Simo Piiroinen <simo.piiroinen@nokia.com>:
 *  Smaps information related to shared, private, clean and dirty pages.
 *
 *  Paul Mundt <paul.mundt@nokia.com>:
 *  Overall revision about smaps.
 */

#include <asm/uaccess.h>

#include <linux/errno.h>
#include <linux/time.h>
#include <linux/proc_fs.h>
#include <linux/stat.h>
#include <linux/init.h>
#include <linux/capability.h>
#include <linux/file.h>
#include <linux/string.h>
#include <linux/seq_file.h>
#include <linux/namei.h>
#include <linux/mnt_namespace.h>
#include <linux/mm.h>
#include <linux/rcupdate.h>
#include <linux/kallsyms.h>
#include <linux/resource.h>
#include <linux/module.h>
#include <linux/mount.h>
#include <linux/security.h>
#include <linux/ptrace.h>
#include <linux/cgroup.h>
#include <linux/cpuset.h>
#include <linux/audit.h>
#include <linux/poll.h>
#include <linux/nsproxy.h>
#include <linux/oom.h>
#include <linux/elf.h>
#include <linux/pid_namespace.h>
#include "internal.h"

/* NOTE:
 *    Implementing inode permission operations in /proc is almost
 *    certainly an error.  Permission checks need to happen during
 *    each system call not at open time.  The reason is that most of
 *    what we wish to check for permissions in /proc varies at runtime.
 *
 *    The classic example of a problem is opening file descriptors
 *    in /proc for a task before it execs a suid executable.
 */


/* Worst case buffer size needed for holding an integer. */
#define PROC_NUMBUF 13

struct pid_entry {
      char *name;
      int len;
      mode_t mode;
      const struct inode_operations *iop;
      const struct file_operations *fop;
      union proc_op op;
};

#define NOD(NAME, MODE, IOP, FOP, OP) {               \
      .name = (NAME),                           \
      .len  = sizeof(NAME) - 1,                 \
      .mode = MODE,                             \
      .iop  = IOP,                              \
      .fop  = FOP,                              \
      .op   = OP,                         \
}

#define DIR(NAME, MODE, OTYPE)                                          \
      NOD(NAME, (S_IFDIR|(MODE)),                                 \
            &proc_##OTYPE##_inode_operations, &proc_##OTYPE##_operations,     \
            {} )
#define LNK(NAME, OTYPE)                              \
      NOD(NAME, (S_IFLNK|S_IRWXUGO),                        \
            &proc_pid_link_inode_operations, NULL,          \
            { .proc_get_link = &proc_##OTYPE##_link } )
#define REG(NAME, MODE, OTYPE)                        \
      NOD(NAME, (S_IFREG|(MODE)), NULL,         \
            &proc_##OTYPE##_operations, {})
#define INF(NAME, MODE, OTYPE)                        \
      NOD(NAME, (S_IFREG|(MODE)),               \
            NULL, &proc_info_file_operations,   \
            { .proc_read = &proc_##OTYPE } )

int maps_protect;
EXPORT_SYMBOL(maps_protect);

static struct fs_struct *get_fs_struct(struct task_struct *task)
{
      struct fs_struct *fs;
      task_lock(task);
      fs = task->fs;
      if(fs)
            atomic_inc(&fs->count);
      task_unlock(task);
      return fs;
}

static int get_nr_threads(struct task_struct *tsk)
{
      /* Must be called with the rcu_read_lock held */
      unsigned long flags;
      int count = 0;

      if (lock_task_sighand(tsk, &flags)) {
            count = atomic_read(&tsk->signal->count);
            unlock_task_sighand(tsk, &flags);
      }
      return count;
}

static int proc_cwd_link(struct inode *inode, struct dentry **dentry, struct vfsmount **mnt)
{
      struct task_struct *task = get_proc_task(inode);
      struct fs_struct *fs = NULL;
      int result = -ENOENT;

      if (task) {
            fs = get_fs_struct(task);
            put_task_struct(task);
      }
      if (fs) {
            read_lock(&fs->lock);
            *mnt = mntget(fs->pwdmnt);
            *dentry = dget(fs->pwd);
            read_unlock(&fs->lock);
            result = 0;
            put_fs_struct(fs);
      }
      return result;
}

static int proc_root_link(struct inode *inode, struct dentry **dentry, struct vfsmount **mnt)
{
      struct task_struct *task = get_proc_task(inode);
      struct fs_struct *fs = NULL;
      int result = -ENOENT;

      if (task) {
            fs = get_fs_struct(task);
            put_task_struct(task);
      }
      if (fs) {
            read_lock(&fs->lock);
            *mnt = mntget(fs->rootmnt);
            *dentry = dget(fs->root);
            read_unlock(&fs->lock);
            result = 0;
            put_fs_struct(fs);
      }
      return result;
}

#define MAY_PTRACE(task) \
      (task == current || \
      (task->parent == current && \
      (task->ptrace & PT_PTRACED) && \
       (task->state == TASK_STOPPED || task->state == TASK_TRACED) && \
       security_ptrace(current,task) == 0))

struct mm_struct *mm_for_maps(struct task_struct *task)
{
      struct mm_struct *mm = get_task_mm(task);
      if (!mm)
            return NULL;
      down_read(&mm->mmap_sem);
      task_lock(task);
      if (task->mm != mm)
            goto out;
      if (task->mm != current->mm && __ptrace_may_attach(task) < 0)
            goto out;
      task_unlock(task);
      return mm;
out:
      task_unlock(task);
      up_read(&mm->mmap_sem);
      mmput(mm);
      return NULL;
}

static int proc_pid_cmdline(struct task_struct *task, char * buffer)
{
      int res = 0;
      unsigned int len;
      struct mm_struct *mm = get_task_mm(task);
      if (!mm)
            goto out;
      if (!mm->arg_end)
            goto out_mm;      /* Shh! No looking before we're done */

      len = mm->arg_end - mm->arg_start;
 
      if (len > PAGE_SIZE)
            len = PAGE_SIZE;
 
      res = access_process_vm(task, mm->arg_start, buffer, len, 0);

      // If the nul at the end of args has been overwritten, then
      // assume application is using setproctitle(3).
      if (res > 0 && buffer[res-1] != '\0' && len < PAGE_SIZE) {
            len = strnlen(buffer, res);
            if (len < res) {
                res = len;
            } else {
                  len = mm->env_end - mm->env_start;
                  if (len > PAGE_SIZE - res)
                        len = PAGE_SIZE - res;
                  res += access_process_vm(task, mm->env_start, buffer+res, len, 0);
                  res = strnlen(buffer, res);
            }
      }
out_mm:
      mmput(mm);
out:
      return res;
}

static int proc_pid_auxv(struct task_struct *task, char *buffer)
{
      int res = 0;
      struct mm_struct *mm = get_task_mm(task);
      if (mm) {
            unsigned int nwords = 0;
            do
                  nwords += 2;
            while (mm->saved_auxv[nwords - 2] != 0); /* AT_NULL */
            res = nwords * sizeof(mm->saved_auxv[0]);
            if (res > PAGE_SIZE)
                  res = PAGE_SIZE;
            memcpy(buffer, mm->saved_auxv, res);
            mmput(mm);
      }
      return res;
}


#ifdef CONFIG_KALLSYMS
/*
 * Provides a wchan file via kallsyms in a proper one-value-per-file format.
 * Returns the resolved symbol.  If that fails, simply return the address.
 */
static int proc_pid_wchan(struct task_struct *task, char *buffer)
{
      unsigned long wchan;
      char symname[KSYM_NAME_LEN];

      wchan = get_wchan(task);

      if (lookup_symbol_name(wchan, symname) < 0)
            return sprintf(buffer, "%lu", wchan);
      else
            return sprintf(buffer, "%s", symname);
}
#endif /* CONFIG_KALLSYMS */

#ifdef CONFIG_SCHEDSTATS
/*
 * Provides /proc/PID/schedstat
 */
static int proc_pid_schedstat(struct task_struct *task, char *buffer)
{
      return sprintf(buffer, "%llu %llu %lu\n",
                  task->sched_info.cpu_time,
                  task->sched_info.run_delay,
                  task->sched_info.pcount);
}
#endif

/* The badness from the OOM killer */
unsigned long badness(struct task_struct *p, unsigned long uptime);
static int proc_oom_score(struct task_struct *task, char *buffer)
{
      unsigned long points;
      struct timespec uptime;

      do_posix_clock_monotonic_gettime(&uptime);
      read_lock(&tasklist_lock);
      points = badness(task, uptime.tv_sec);
      read_unlock(&tasklist_lock);
      return sprintf(buffer, "%lu\n", points);
}

struct limit_names {
      char *name;
      char *unit;
};

static const struct limit_names lnames[RLIM_NLIMITS] = {
      [RLIMIT_CPU] = {"Max cpu time", "ms"},
      [RLIMIT_FSIZE] = {"Max file size", "bytes"},
      [RLIMIT_DATA] = {"Max data size", "bytes"},
      [RLIMIT_STACK] = {"Max stack size", "bytes"},
      [RLIMIT_CORE] = {"Max core file size", "bytes"},
      [RLIMIT_RSS] = {"Max resident set", "bytes"},
      [RLIMIT_NPROC] = {"Max processes", "processes"},
      [RLIMIT_NOFILE] = {"Max open files", "files"},
      [RLIMIT_MEMLOCK] = {"Max locked memory", "bytes"},
      [RLIMIT_AS] = {"Max address space", "bytes"},
      [RLIMIT_LOCKS] = {"Max file locks", "locks"},
      [RLIMIT_SIGPENDING] = {"Max pending signals", "signals"},
      [RLIMIT_MSGQUEUE] = {"Max msgqueue size", "bytes"},
      [RLIMIT_NICE] = {"Max nice priority", NULL},
      [RLIMIT_RTPRIO] = {"Max realtime priority", NULL},
};

/* Display limits for a process */
static int proc_pid_limits(struct task_struct *task, char *buffer)
{
      unsigned int i;
      int count = 0;
      unsigned long flags;
      char *bufptr = buffer;

      struct rlimit rlim[RLIM_NLIMITS];

      rcu_read_lock();
      if (!lock_task_sighand(task,&flags)) {
            rcu_read_unlock();
            return 0;
      }
      memcpy(rlim, task->signal->rlim, sizeof(struct rlimit) * RLIM_NLIMITS);
      unlock_task_sighand(task, &flags);
      rcu_read_unlock();

      /*
       * print the file header
       */
      count += sprintf(&bufptr[count], "%-25s %-20s %-20s %-10s\n",
                  "Limit", "Soft Limit", "Hard Limit", "Units");

      for (i = 0; i < RLIM_NLIMITS; i++) {
            if (rlim[i].rlim_cur == RLIM_INFINITY)
                  count += sprintf(&bufptr[count], "%-25s %-20s ",
                               lnames[i].name, "unlimited");
            else
                  count += sprintf(&bufptr[count], "%-25s %-20lu ",
                               lnames[i].name, rlim[i].rlim_cur);

            if (rlim[i].rlim_max == RLIM_INFINITY)
                  count += sprintf(&bufptr[count], "%-20s ", "unlimited");
            else
                  count += sprintf(&bufptr[count], "%-20lu ",
                               rlim[i].rlim_max);

            if (lnames[i].unit)
                  count += sprintf(&bufptr[count], "%-10s\n",
                               lnames[i].unit);
            else
                  count += sprintf(&bufptr[count], "\n");
      }

      return count;
}

/************************************************************************/
/*                       Here the fs part begins                        */
/************************************************************************/

/* permission checks */
static int proc_fd_access_allowed(struct inode *inode)
{
      struct task_struct *task;
      int allowed = 0;
      /* Allow access to a task's file descriptors if it is us or we
       * may use ptrace attach to the process and find out that
       * information.
       */
      task = get_proc_task(inode);
      if (task) {
            allowed = ptrace_may_attach(task);
            put_task_struct(task);
      }
      return allowed;
}

static int proc_setattr(struct dentry *dentry, struct iattr *attr)
{
      int error;
      struct inode *inode = dentry->d_inode;

      if (attr->ia_valid & ATTR_MODE)
            return -EPERM;

      error = inode_change_ok(inode, attr);
      if (!error)
            error = inode_setattr(inode, attr);
      return error;
}

static const struct inode_operations proc_def_inode_operations = {
      .setattr    = proc_setattr,
};

extern struct seq_operations mounts_op;
struct proc_mounts {
      struct seq_file m;
      int event;
};

static int mounts_open(struct inode *inode, struct file *file)
{
      struct task_struct *task = get_proc_task(inode);
      struct nsproxy *nsp;
      struct mnt_namespace *ns = NULL;
      struct proc_mounts *p;
      int ret = -EINVAL;

      if (task) {
            rcu_read_lock();
            nsp = task_nsproxy(task);
            if (nsp) {
                  ns = nsp->mnt_ns;
                  if (ns)
                        get_mnt_ns(ns);
            }
            rcu_read_unlock();

            put_task_struct(task);
      }

      if (ns) {
            ret = -ENOMEM;
            p = kmalloc(sizeof(struct proc_mounts), GFP_KERNEL);
            if (p) {
                  file->private_data = &p->m;
                  ret = seq_open(file, &mounts_op);
                  if (!ret) {
                        p->m.private = ns;
                        p->event = ns->event;
                        return 0;
                  }
                  kfree(p);
            }
            put_mnt_ns(ns);
      }
      return ret;
}

static int mounts_release(struct inode *inode, struct file *file)
{
      struct seq_file *m = file->private_data;
      struct mnt_namespace *ns = m->private;
      put_mnt_ns(ns);
      return seq_release(inode, file);
}

static unsigned mounts_poll(struct file *file, poll_table *wait)
{
      struct proc_mounts *p = file->private_data;
      struct mnt_namespace *ns = p->m.private;
      unsigned res = 0;

      poll_wait(file, &ns->poll, wait);

      spin_lock(&vfsmount_lock);
      if (p->event != ns->event) {
            p->event = ns->event;
            res = POLLERR;
      }
      spin_unlock(&vfsmount_lock);

      return res;
}

static const struct file_operations proc_mounts_operations = {
      .open       = mounts_open,
      .read       = seq_read,
      .llseek           = seq_lseek,
      .release    = mounts_release,
      .poll       = mounts_poll,
};

extern struct seq_operations mountstats_op;
static int mountstats_open(struct inode *inode, struct file *file)
{
      int ret = seq_open(file, &mountstats_op);

      if (!ret) {
            struct seq_file *m = file->private_data;
            struct nsproxy *nsp;
            struct mnt_namespace *mnt_ns = NULL;
            struct task_struct *task = get_proc_task(inode);

            if (task) {
                  rcu_read_lock();
                  nsp = task_nsproxy(task);
                  if (nsp) {
                        mnt_ns = nsp->mnt_ns;
                        if (mnt_ns)
                              get_mnt_ns(mnt_ns);
                  }
                  rcu_read_unlock();

                  put_task_struct(task);
            }

            if (mnt_ns)
                  m->private = mnt_ns;
            else {
                  seq_release(inode, file);
                  ret = -EINVAL;
            }
      }
      return ret;
}

static const struct file_operations proc_mountstats_operations = {
      .open       = mountstats_open,
      .read       = seq_read,
      .llseek           = seq_lseek,
      .release    = mounts_release,
};

#define PROC_BLOCK_SIZE (3*1024)          /* 4K page size but our output routines use some slack for overruns */

static ssize_t proc_info_read(struct file * file, char __user * buf,
                    size_t count, loff_t *ppos)
{
      struct inode * inode = file->f_path.dentry->d_inode;
      unsigned long page;
      ssize_t length;
      struct task_struct *task = get_proc_task(inode);

      length = -ESRCH;
      if (!task)
            goto out_no_task;

      if (count > PROC_BLOCK_SIZE)
            count = PROC_BLOCK_SIZE;

      length = -ENOMEM;
      if (!(page = __get_free_page(GFP_TEMPORARY)))
            goto out;

      length = PROC_I(inode)->op.proc_read(task, (char*)page);

      if (length >= 0)
            length = simple_read_from_buffer(buf, count, ppos, (char *)page, length);
      free_page(page);
out:
      put_task_struct(task);
out_no_task:
      return length;
}

static const struct file_operations proc_info_file_operations = {
      .read       = proc_info_read,
};

static int mem_open(struct inode* inode, struct file* file)
{
      file->private_data = (void*)((long)current->self_exec_id);
      return 0;
}

static ssize_t mem_read(struct file * file, char __user * buf,
                  size_t count, loff_t *ppos)
{
      struct task_struct *task = get_proc_task(file->f_path.dentry->d_inode);
      char *page;
      unsigned long src = *ppos;
      int ret = -ESRCH;
      struct mm_struct *mm;

      if (!task)
            goto out_no_task;

      if (!MAY_PTRACE(task) || !ptrace_may_attach(task))
            goto out;

      ret = -ENOMEM;
      page = (char *)__get_free_page(GFP_TEMPORARY);
      if (!page)
            goto out;

      ret = 0;
 
      mm = get_task_mm(task);
      if (!mm)
            goto out_free;

      ret = -EIO;
 
      if (file->private_data != (void*)((long)current->self_exec_id))
            goto out_put;

      ret = 0;
 
      while (count > 0) {
            int this_len, retval;

            this_len = (count > PAGE_SIZE) ? PAGE_SIZE : count;
            retval = access_process_vm(task, src, page, this_len, 0);
            if (!retval || !MAY_PTRACE(task) || !ptrace_may_attach(task)) {
                  if (!ret)
                        ret = -EIO;
                  break;
            }

            if (copy_to_user(buf, page, retval)) {
                  ret = -EFAULT;
                  break;
            }
 
            ret += retval;
            src += retval;
            buf += retval;
            count -= retval;
      }
      *ppos = src;

out_put:
      mmput(mm);
out_free:
      free_page((unsigned long) page);
out:
      put_task_struct(task);
out_no_task:
      return ret;
}

#define mem_write NULL

#ifndef mem_write
/* This is a security hazard */
static ssize_t mem_write(struct file * file, const char __user *buf,
                   size_t count, loff_t *ppos)
{
      int copied;
      char *page;
      struct task_struct *task = get_proc_task(file->f_path.dentry->d_inode);
      unsigned long dst = *ppos;

      copied = -ESRCH;
      if (!task)
            goto out_no_task;

      if (!MAY_PTRACE(task) || !ptrace_may_attach(task))
            goto out;

      copied = -ENOMEM;
      page = (char *)__get_free_page(GFP_TEMPORARY);
      if (!page)
            goto out;

      copied = 0;
      while (count > 0) {
            int this_len, retval;

            this_len = (count > PAGE_SIZE) ? PAGE_SIZE : count;
            if (copy_from_user(page, buf, this_len)) {
                  copied = -EFAULT;
                  break;
            }
            retval = access_process_vm(task, dst, page, this_len, 1);
            if (!retval) {
                  if (!copied)
                        copied = -EIO;
                  break;
            }
            copied += retval;
            buf += retval;
            dst += retval;
            count -= retval;              
      }
      *ppos = dst;
      free_page((unsigned long) page);
out:
      put_task_struct(task);
out_no_task:
      return copied;
}
#endif

static loff_t mem_lseek(struct file * file, loff_t offset, int orig)
{
      switch (orig) {
      case 0:
            file->f_pos = offset;
            break;
      case 1:
            file->f_pos += offset;
            break;
      default:
            return -EINVAL;
      }
      force_successful_syscall_return();
      return file->f_pos;
}

static const struct file_operations proc_mem_operations = {
      .llseek           = mem_lseek,
      .read       = mem_read,
      .write            = mem_write,
      .open       = mem_open,
};

static ssize_t environ_read(struct file *file, char __user *buf,
                  size_t count, loff_t *ppos)
{
      struct task_struct *task = get_proc_task(file->f_dentry->d_inode);
      char *page;
      unsigned long src = *ppos;
      int ret = -ESRCH;
      struct mm_struct *mm;

      if (!task)
            goto out_no_task;

      if (!ptrace_may_attach(task))
            goto out;

      ret = -ENOMEM;
      page = (char *)__get_free_page(GFP_TEMPORARY);
      if (!page)
            goto out;

      ret = 0;

      mm = get_task_mm(task);
      if (!mm)
            goto out_free;

      while (count > 0) {
            int this_len, retval, max_len;

            this_len = mm->env_end - (mm->env_start + src);

            if (this_len <= 0)
                  break;

            max_len = (count > PAGE_SIZE) ? PAGE_SIZE : count;
            this_len = (this_len > max_len) ? max_len : this_len;

            retval = access_process_vm(task, (mm->env_start + src),
                  page, this_len, 0);

            if (retval <= 0) {
                  ret = retval;
                  break;
            }

            if (copy_to_user(buf, page, retval)) {
                  ret = -EFAULT;
                  break;
            }

            ret += retval;
            src += retval;
            buf += retval;
            count -= retval;
      }
      *ppos = src;

      mmput(mm);
out_free:
      free_page((unsigned long) page);
out:
      put_task_struct(task);
out_no_task:
      return ret;
}

static const struct file_operations proc_environ_operations = {
      .read       = environ_read,
};

static ssize_t oom_adjust_read(struct file *file, char __user *buf,
                        size_t count, loff_t *ppos)
{
      struct task_struct *task = get_proc_task(file->f_path.dentry->d_inode);
      char buffer[PROC_NUMBUF];
      size_t len;
      int oom_adjust;

      if (!task)
            return -ESRCH;
      oom_adjust = task->oomkilladj;
      put_task_struct(task);

      len = snprintf(buffer, sizeof(buffer), "%i\n", oom_adjust);

      return simple_read_from_buffer(buf, count, ppos, buffer, len);
}

static ssize_t oom_adjust_write(struct file *file, const char __user *buf,
                        size_t count, loff_t *ppos)
{
      struct task_struct *task;
      char buffer[PROC_NUMBUF], *end;
      int oom_adjust;

      memset(buffer, 0, sizeof(buffer));
      if (count > sizeof(buffer) - 1)
            count = sizeof(buffer) - 1;
      if (copy_from_user(buffer, buf, count))
            return -EFAULT;
      oom_adjust = simple_strtol(buffer, &end, 0);
      if ((oom_adjust < OOM_ADJUST_MIN || oom_adjust > OOM_ADJUST_MAX) &&
           oom_adjust != OOM_DISABLE)
            return -EINVAL;
      if (*end == '\n')
            end++;
      task = get_proc_task(file->f_path.dentry->d_inode);
      if (!task)
            return -ESRCH;
      if (oom_adjust < task->oomkilladj && !capable(CAP_SYS_RESOURCE)) {
            put_task_struct(task);
            return -EACCES;
      }
      task->oomkilladj = oom_adjust;
      put_task_struct(task);
      if (end - buffer == 0)
            return -EIO;
      return end - buffer;
}

static const struct file_operations proc_oom_adjust_operations = {
      .read       = oom_adjust_read,
      .write            = oom_adjust_write,
};

#ifdef CONFIG_MMU
static ssize_t clear_refs_write(struct file *file, const char __user *buf,
                        size_t count, loff_t *ppos)
{
      struct task_struct *task;
      char buffer[PROC_NUMBUF], *end;
      struct mm_struct *mm;

      memset(buffer, 0, sizeof(buffer));
      if (count > sizeof(buffer) - 1)
            count = sizeof(buffer) - 1;
      if (copy_from_user(buffer, buf, count))
            return -EFAULT;
      if (!simple_strtol(buffer, &end, 0))
            return -EINVAL;
      if (*end == '\n')
            end++;
      task = get_proc_task(file->f_path.dentry->d_inode);
      if (!task)
            return -ESRCH;
      mm = get_task_mm(task);
      if (mm) {
            clear_refs_smap(mm);
            mmput(mm);
      }
      put_task_struct(task);
      if (end - buffer == 0)
            return -EIO;
      return end - buffer;
}

static struct file_operations proc_clear_refs_operations = {
      .write            = clear_refs_write,
};
#endif

#ifdef CONFIG_AUDITSYSCALL
#define TMPBUFLEN 21
static ssize_t proc_loginuid_read(struct file * file, char __user * buf,
                          size_t count, loff_t *ppos)
{
      struct inode * inode = file->f_path.dentry->d_inode;
      struct task_struct *task = get_proc_task(inode);
      ssize_t length;
      char tmpbuf[TMPBUFLEN];

      if (!task)
            return -ESRCH;
      length = scnprintf(tmpbuf, TMPBUFLEN, "%u",
                        audit_get_loginuid(task->audit_context));
      put_task_struct(task);
      return simple_read_from_buffer(buf, count, ppos, tmpbuf, length);
}

static ssize_t proc_loginuid_write(struct file * file, const char __user * buf,
                           size_t count, loff_t *ppos)
{
      struct inode * inode = file->f_path.dentry->d_inode;
      char *page, *tmp;
      ssize_t length;
      uid_t loginuid;

      if (!capable(CAP_AUDIT_CONTROL))
            return -EPERM;

      if (current != pid_task(proc_pid(inode), PIDTYPE_PID))
            return -EPERM;

      if (count >= PAGE_SIZE)
            count = PAGE_SIZE - 1;

      if (*ppos != 0) {
            /* No partial writes. */
            return -EINVAL;
      }
      page = (char*)__get_free_page(GFP_TEMPORARY);
      if (!page)
            return -ENOMEM;
      length = -EFAULT;
      if (copy_from_user(page, buf, count))
            goto out_free_page;

      page[count] = '\0';
      loginuid = simple_strtoul(page, &tmp, 10);
      if (tmp == page) {
            length = -EINVAL;
            goto out_free_page;

      }
      length = audit_set_loginuid(current, loginuid);
      if (likely(length == 0))
            length = count;

out_free_page:
      free_page((unsigned long) page);
      return length;
}

static const struct file_operations proc_loginuid_operations = {
      .read       = proc_loginuid_read,
      .write            = proc_loginuid_write,
};
#endif

#ifdef CONFIG_FAULT_INJECTION
static ssize_t proc_fault_inject_read(struct file * file, char __user * buf,
                              size_t count, loff_t *ppos)
{
      struct task_struct *task = get_proc_task(file->f_dentry->d_inode);
      char buffer[PROC_NUMBUF];
      size_t len;
      int make_it_fail;

      if (!task)
            return -ESRCH;
      make_it_fail = task->make_it_fail;
      put_task_struct(task);

      len = snprintf(buffer, sizeof(buffer), "%i\n", make_it_fail);

      return simple_read_from_buffer(buf, count, ppos, buffer, len);
}

static ssize_t proc_fault_inject_write(struct file * file,
                  const char __user * buf, size_t count, loff_t *ppos)
{
      struct task_struct *task;
      char buffer[PROC_NUMBUF], *end;
      int make_it_fail;

      if (!capable(CAP_SYS_RESOURCE))
            return -EPERM;
      memset(buffer, 0, sizeof(buffer));
      if (count > sizeof(buffer) - 1)
            count = sizeof(buffer) - 1;
      if (copy_from_user(buffer, buf, count))
            return -EFAULT;
      make_it_fail = simple_strtol(buffer, &end, 0);
      if (*end == '\n')
            end++;
      task = get_proc_task(file->f_dentry->d_inode);
      if (!task)
            return -ESRCH;
      task->make_it_fail = make_it_fail;
      put_task_struct(task);
      if (end - buffer == 0)
            return -EIO;
      return end - buffer;
}

static const struct file_operations proc_fault_inject_operations = {
      .read       = proc_fault_inject_read,
      .write            = proc_fault_inject_write,
};
#endif

#ifdef CONFIG_SCHED_DEBUG
/*
 * Print out various scheduling related per-task fields:
 */
static int sched_show(struct seq_file *m, void *v)
{
      struct inode *inode = m->private;
      struct task_struct *p;

      WARN_ON(!inode);

      p = get_proc_task(inode);
      if (!p)
            return -ESRCH;
      proc_sched_show_task(p, m);

      put_task_struct(p);

      return 0;
}

static ssize_t
sched_write(struct file *file, const char __user *buf,
          size_t count, loff_t *offset)
{
      struct inode *inode = file->f_path.dentry->d_inode;
      struct task_struct *p;

      WARN_ON(!inode);

      p = get_proc_task(inode);
      if (!p)
            return -ESRCH;
      proc_sched_set_task(p);

      put_task_struct(p);

      return count;
}

static int sched_open(struct inode *inode, struct file *filp)
{
      int ret;

      ret = single_open(filp, sched_show, NULL);
      if (!ret) {
            struct seq_file *m = filp->private_data;

            m->private = inode;
      }
      return ret;
}

static const struct file_operations proc_pid_sched_operations = {
      .open       = sched_open,
      .read       = seq_read,
      .write            = sched_write,
      .llseek           = seq_lseek,
      .release    = single_release,
};

#endif

static void *proc_pid_follow_link(struct dentry *dentry, struct nameidata *nd)
{
      struct inode *inode = dentry->d_inode;
      int error = -EACCES;

      /* We don't need a base pointer in the /proc filesystem */
      path_release(nd);

      /* Are we allowed to snoop on the tasks file descriptors? */
      if (!proc_fd_access_allowed(inode))
            goto out;

      error = PROC_I(inode)->op.proc_get_link(inode, &nd->dentry, &nd->mnt);
      nd->last_type = LAST_BIND;
out:
      return ERR_PTR(error);
}

static int do_proc_readlink(struct dentry *dentry, struct vfsmount *mnt,
                      char __user *buffer, int buflen)
{
      struct inode * inode;
      char *tmp = (char*)__get_free_page(GFP_TEMPORARY);
      char *path;
      int len;

      if (!tmp)
            return -ENOMEM;

      inode = dentry->d_inode;
      path = d_path(dentry, mnt, tmp, PAGE_SIZE);
      len = PTR_ERR(path);
      if (IS_ERR(path))
            goto out;
      len = tmp + PAGE_SIZE - 1 - path;

      if (len > buflen)
            len = buflen;
      if (copy_to_user(buffer, path, len))
            len = -EFAULT;
 out:
      free_page((unsigned long)tmp);
      return len;
}

static int proc_pid_readlink(struct dentry * dentry, char __user * buffer, int buflen)
{
      int error = -EACCES;
      struct inode *inode = dentry->d_inode;
      struct dentry *de;
      struct vfsmount *mnt = NULL;

      /* Are we allowed to snoop on the tasks file descriptors? */
      if (!proc_fd_access_allowed(inode))
            goto out;

      error = PROC_I(inode)->op.proc_get_link(inode, &de, &mnt);
      if (error)
            goto out;

      error = do_proc_readlink(de, mnt, buffer, buflen);
      dput(de);
      mntput(mnt);
out:
      return error;
}

static const struct inode_operations proc_pid_link_inode_operations = {
      .readlink   = proc_pid_readlink,
      .follow_link      = proc_pid_follow_link,
      .setattr    = proc_setattr,
};


/* building an inode */

static int task_dumpable(struct task_struct *task)
{
      int dumpable = 0;
      struct mm_struct *mm;

      task_lock(task);
      mm = task->mm;
      if (mm)
            dumpable = get_dumpable(mm);
      task_unlock(task);
      if(dumpable == 1)
            return 1;
      return 0;
}


static struct inode *proc_pid_make_inode(struct super_block * sb, struct task_struct *task)
{
      struct inode * inode;
      struct proc_inode *ei;

      /* We need a new inode */

      inode = new_inode(sb);
      if (!inode)
            goto out;

      /* Common stuff */
      ei = PROC_I(inode);
      inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
      inode->i_op = &proc_def_inode_operations;

      /*
       * grab the reference to task.
       */
      ei->pid = get_task_pid(task, PIDTYPE_PID);
      if (!ei->pid)
            goto out_unlock;

      inode->i_uid = 0;
      inode->i_gid = 0;
      if (task_dumpable(task)) {
            inode->i_uid = task->euid;
            inode->i_gid = task->egid;
      }
      security_task_to_inode(task, inode);

out:
      return inode;

out_unlock:
      iput(inode);
      return NULL;
}

static int pid_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
{
      struct inode *inode = dentry->d_inode;
      struct task_struct *task;
      generic_fillattr(inode, stat);

      rcu_read_lock();
      stat->uid = 0;
      stat->gid = 0;
      task = pid_task(proc_pid(inode), PIDTYPE_PID);
      if (task) {
            if ((inode->i_mode == (S_IFDIR|S_IRUGO|S_IXUGO)) ||
                task_dumpable(task)) {
                  stat->uid = task->euid;
                  stat->gid = task->egid;
            }
      }
      rcu_read_unlock();
      return 0;
}

/* dentry stuff */

/*
 *    Exceptional case: normally we are not allowed to unhash a busy
 * directory. In this case, however, we can do it - no aliasing problems
 * due to the way we treat inodes.
 *
 * Rewrite the inode's ownerships here because the owning task may have
 * performed a setuid(), etc.
 *
 * Before the /proc/pid/status file was created the only way to read
 * the effective uid of a /process was to stat /proc/pid.  Reading
 * /proc/pid/status is slow enough that procps and other packages
 * kept stating /proc/pid.  To keep the rules in /proc simple I have
 * made this apply to all per process world readable and executable
 * directories.
 */
static int pid_revalidate(struct dentry *dentry, struct nameidata *nd)
{
      struct inode *inode = dentry->d_inode;
      struct task_struct *task = get_proc_task(inode);
      if (task) {
            if ((inode->i_mode == (S_IFDIR|S_IRUGO|S_IXUGO)) ||
                task_dumpable(task)) {
                  inode->i_uid = task->euid;
                  inode->i_gid = task->egid;
            } else {
                  inode->i_uid = 0;
                  inode->i_gid = 0;
            }
            inode->i_mode &= ~(S_ISUID | S_ISGID);
            security_task_to_inode(task, inode);
            put_task_struct(task);
            return 1;
      }
      d_drop(dentry);
      return 0;
}

static int pid_delete_dentry(struct dentry * dentry)
{
      /* Is the task we represent dead?
       * If so, then don't put the dentry on the lru list,
       * kill it immediately.
       */
      return !proc_pid(dentry->d_inode)->tasks[PIDTYPE_PID].first;
}

static struct dentry_operations pid_dentry_operations =
{
      .d_revalidate     = pid_revalidate,
      .d_delete   = pid_delete_dentry,
};

/* Lookups */

typedef struct dentry *instantiate_t(struct inode *, struct dentry *,
                        struct task_struct *, const void *);

/*
 * Fill a directory entry.
 *
 * If possible create the dcache entry and derive our inode number and
 * file type from dcache entry.
 *
 * Since all of the proc inode numbers are dynamically generated, the inode
 * numbers do not exist until the inode is cache.  This means creating the
 * the dcache entry in readdir is necessary to keep the inode numbers
 * reported by readdir in sync with the inode numbers reported
 * by stat.
 */
static int proc_fill_cache(struct file *filp, void *dirent, filldir_t filldir,
      char *name, int len,
      instantiate_t instantiate, struct task_struct *task, const void *ptr)
{
      struct dentry *child, *dir = filp->f_path.dentry;
      struct inode *inode;
      struct qstr qname;
      ino_t ino = 0;
      unsigned type = DT_UNKNOWN;

      qname.name = name;
      qname.len  = len;
      qname.hash = full_name_hash(name, len);

      child = d_lookup(dir, &qname);
      if (!child) {
            struct dentry *new;
            new = d_alloc(dir, &qname);
            if (new) {
                  child = instantiate(dir->d_inode, new, task, ptr);
                  if (child)
                        dput(new);
                  else
                        child = new;
            }
      }
      if (!child || IS_ERR(child) || !child->d_inode)
            goto end_instantiate;
      inode = child->d_inode;
      if (inode) {
            ino = inode->i_ino;
            type = inode->i_mode >> 12;
      }
      dput(child);
end_instantiate:
      if (!ino)
            ino = find_inode_number(dir, &qname);
      if (!ino)
            ino = 1;
      return filldir(dirent, name, len, filp->f_pos, ino, type);
}

static unsigned name_to_int(struct dentry *dentry)
{
      const char *name = dentry->d_name.name;
      int len = dentry->d_name.len;
      unsigned n = 0;

      if (len > 1 && *name == '0')
            goto out;
      while (len-- > 0) {
            unsigned c = *name++ - '0';
            if (c > 9)
                  goto out;
            if (n >= (~0U-9)/10)
                  goto out;
            n *= 10;
            n += c;
      }
      return n;
out:
      return ~0U;
}

#define PROC_FDINFO_MAX 64

static int proc_fd_info(struct inode *inode, struct dentry **dentry,
                  struct vfsmount **mnt, char *info)
{
      struct task_struct *task = get_proc_task(inode);
      struct files_struct *files = NULL;
      struct file *file;
      int fd = proc_fd(inode);

      if (task) {
            files = get_files_struct(task);
            put_task_struct(task);
      }
      if (files) {
            /*
             * We are not taking a ref to the file structure, so we must
             * hold ->file_lock.
             */
            spin_lock(&files->file_lock);
            file = fcheck_files(files, fd);
            if (file) {
                  if (mnt)
                        *mnt = mntget(file->f_path.mnt);
                  if (dentry)
                        *dentry = dget(file->f_path.dentry);
                  if (info)
                        snprintf(info, PROC_FDINFO_MAX,
                               "pos:\t%lli\n"
                               "flags:\t0%o\n",
                               (long long) file->f_pos,
                               file->f_flags);
                  spin_unlock(&files->file_lock);
                  put_files_struct(files);
                  return 0;
            }
            spin_unlock(&files->file_lock);
            put_files_struct(files);
      }
      return -ENOENT;
}

static int proc_fd_link(struct inode *inode, struct dentry **dentry,
                  struct vfsmount **mnt)
{
      return proc_fd_info(inode, dentry, mnt, NULL);
}

static int tid_fd_revalidate(struct dentry *dentry, struct nameidata *nd)
{
      struct inode *inode = dentry->d_inode;
      struct task_struct *task = get_proc_task(inode);
      int fd = proc_fd(inode);
      struct files_struct *files;

      if (task) {
            files = get_files_struct(task);
            if (files) {
                  rcu_read_lock();
                  if (fcheck_files(files, fd)) {
                        rcu_read_unlock();
                        put_files_struct(files);
                        if (task_dumpable(task)) {
                              inode->i_uid = task->euid;
                              inode->i_gid = task->egid;
                        } else {
                              inode->i_uid = 0;
                              inode->i_gid = 0;
                        }
                        inode->i_mode &= ~(S_ISUID | S_ISGID);
                        security_task_to_inode(task, inode);
                        put_task_struct(task);
                        return 1;
                  }
                  rcu_read_unlock();
                  put_files_struct(files);
            }
            put_task_struct(task);
      }
      d_drop(dentry);
      return 0;
}

static struct dentry_operations tid_fd_dentry_operations =
{
      .d_revalidate     = tid_fd_revalidate,
      .d_delete   = pid_delete_dentry,
};

static struct dentry *proc_fd_instantiate(struct inode *dir,
      struct dentry *dentry, struct task_struct *task, const void *ptr)
{
      unsigned fd = *(const unsigned *)ptr;
      struct file *file;
      struct files_struct *files;
      struct inode *inode;
      struct proc_inode *ei;
      struct dentry *error = ERR_PTR(-ENOENT);

      inode = proc_pid_make_inode(dir->i_sb, task);
      if (!inode)
            goto out;
      ei = PROC_I(inode);
      ei->fd = fd;
      files = get_files_struct(task);
      if (!files)
            goto out_iput;
      inode->i_mode = S_IFLNK;

      /*
       * We are not taking a ref to the file structure, so we must
       * hold ->file_lock.
       */
      spin_lock(&files->file_lock);
      file = fcheck_files(files, fd);
      if (!file)
            goto out_unlock;
      if (file->f_mode & 1)
            inode->i_mode |= S_IRUSR | S_IXUSR;
      if (file->f_mode & 2)
            inode->i_mode |= S_IWUSR | S_IXUSR;
      spin_unlock(&files->file_lock);
      put_files_struct(files);

      inode->i_op = &proc_pid_link_inode_operations;
      inode->i_size = 64;
      ei->op.proc_get_link = proc_fd_link;
      dentry->d_op = &tid_fd_dentry_operations;
      d_add(dentry, inode);
      /* Close the race of the process dying before we return the dentry */
      if (tid_fd_revalidate(dentry, NULL))
            error = NULL;

 out:
      return error;
out_unlock:
      spin_unlock(&files->file_lock);
      put_files_struct(files);
out_iput:
      iput(inode);
      goto out;
}

static struct dentry *proc_lookupfd_common(struct inode *dir,
                                 struct dentry *dentry,
                                 instantiate_t instantiate)
{
      struct task_struct *task = get_proc_task(dir);
      unsigned fd = name_to_int(dentry);
      struct dentry *result = ERR_PTR(-ENOENT);

      if (!task)
            goto out_no_task;
      if (fd == ~0U)
            goto out;

      result = instantiate(dir, dentry, task, &fd);
out:
      put_task_struct(task);
out_no_task:
      return result;
}

static int proc_readfd_common(struct file * filp, void * dirent,
                        filldir_t filldir, instantiate_t instantiate)
{
      struct dentry *dentry = filp->f_path.dentry;
      struct inode *inode = dentry->d_inode;
      struct task_struct *p = get_proc_task(inode);
      unsigned int fd, ino;
      int retval;
      struct files_struct * files;
      struct fdtable *fdt;

      retval = -ENOENT;
      if (!p)
            goto out_no_task;
      retval = 0;

      fd = filp->f_pos;
      switch (fd) {
            case 0:
                  if (filldir(dirent, ".", 1, 0, inode->i_ino, DT_DIR) < 0)
                        goto out;
                  filp->f_pos++;
            case 1:
                  ino = parent_ino(dentry);
                  if (filldir(dirent, "..", 2, 1, ino, DT_DIR) < 0)
                        goto out;
                  filp->f_pos++;
            default:
                  files = get_files_struct(p);
                  if (!files)
                        goto out;
                  rcu_read_lock();
                  fdt = files_fdtable(files);
                  for (fd = filp->f_pos-2;
                       fd < fdt->max_fds;
                       fd++, filp->f_pos++) {
                        char name[PROC_NUMBUF];
                        int len;

                        if (!fcheck_files(files, fd))
                              continue;
                        rcu_read_unlock();

                        len = snprintf(name, sizeof(name), "%d", fd);
                        if (proc_fill_cache(filp, dirent, filldir,
                                        name, len, instantiate,
                                        p, &fd) < 0) {
                              rcu_read_lock();
                              break;
                        }
                        rcu_read_lock();
                  }
                  rcu_read_unlock();
                  put_files_struct(files);
      }
out:
      put_task_struct(p);
out_no_task:
      return retval;
}

static struct dentry *proc_lookupfd(struct inode *dir, struct dentry *dentry,
                            struct nameidata *nd)
{
      return proc_lookupfd_common(dir, dentry, proc_fd_instantiate);
}

static int proc_readfd(struct file *filp, void *dirent, filldir_t filldir)
{
      return proc_readfd_common(filp, dirent, filldir, proc_fd_instantiate);
}

static ssize_t proc_fdinfo_read(struct file *file, char __user *buf,
                              size_t len, loff_t *ppos)
{
      char tmp[PROC_FDINFO_MAX];
      int err = proc_fd_info(file->f_path.dentry->d_inode, NULL, NULL, tmp);
      if (!err)
            err = simple_read_from_buffer(buf, len, ppos, tmp, strlen(tmp));
      return err;
}

static const struct file_operations proc_fdinfo_file_operations = {
      .open       = nonseekable_open,
      .read       = proc_fdinfo_read,
};

static const struct file_operations proc_fd_operations = {
      .read       = generic_read_dir,
      .readdir    = proc_readfd,
};

/*
 * /proc/pid/fd needs a special permission handler so that a process can still
 * access /proc/self/fd after it has executed a setuid().
 */
static int proc_fd_permission(struct inode *inode, int mask,
                        struct nameidata *nd)
{
      int rv;

      rv = generic_permission(inode, mask, NULL);
      if (rv == 0)
            return 0;
      if (task_pid(current) == proc_pid(inode))
            rv = 0;
      return rv;
}

/*
 * proc directories can do almost nothing..
 */
static const struct inode_operations proc_fd_inode_operations = {
      .lookup           = proc_lookupfd,
      .permission = proc_fd_permission,
      .setattr    = proc_setattr,
};

static struct dentry *proc_fdinfo_instantiate(struct inode *dir,
      struct dentry *dentry, struct task_struct *task, const void *ptr)
{
      unsigned fd = *(unsigned *)ptr;
      struct inode *inode;
      struct proc_inode *ei;
      struct dentry *error = ERR_PTR(-ENOENT);

      inode = proc_pid_make_inode(dir->i_sb, task);
      if (!inode)
            goto out;
      ei = PROC_I(inode);
      ei->fd = fd;
      inode->i_mode = S_IFREG | S_IRUSR;
      inode->i_fop = &proc_fdinfo_file_operations;
      dentry->d_op = &tid_fd_dentry_operations;
      d_add(dentry, inode);
      /* Close the race of the process dying before we return the dentry */
      if (tid_fd_revalidate(dentry, NULL))
            error = NULL;

 out:
      return error;
}

static struct dentry *proc_lookupfdinfo(struct inode *dir,
                              struct dentry *dentry,
                              struct nameidata *nd)
{
      return proc_lookupfd_common(dir, dentry, proc_fdinfo_instantiate);
}

static int proc_readfdinfo(struct file *filp, void *dirent, filldir_t filldir)
{
      return proc_readfd_common(filp, dirent, filldir,
                          proc_fdinfo_instantiate);
}

static const struct file_operations proc_fdinfo_operations = {
      .read       = generic_read_dir,
      .readdir    = proc_readfdinfo,
};

/*
 * proc directories can do almost nothing..
 */
static const struct inode_operations proc_fdinfo_inode_operations = {
      .lookup           = proc_lookupfdinfo,
      .setattr    = proc_setattr,
};


static struct dentry *proc_pident_instantiate(struct inode *dir,
      struct dentry *dentry, struct task_struct *task, const void *ptr)
{
      const struct pid_entry *p = ptr;
      struct inode *inode;
      struct proc_inode *ei;
      struct dentry *error = ERR_PTR(-EINVAL);

      inode = proc_pid_make_inode(dir->i_sb, task);
      if (!inode)
            goto out;

      ei = PROC_I(inode);
      inode->i_mode = p->mode;
      if (S_ISDIR(inode->i_mode))
            inode->i_nlink = 2;     /* Use getattr to fix if necessary */
      if (p->iop)
            inode->i_op = p->iop;
      if (p->fop)
            inode->i_fop = p->fop;
      ei->op = p->op;
      dentry->d_op = &pid_dentry_operations;
      d_add(dentry, inode);
      /* Close the race of the process dying before we return the dentry */
      if (pid_revalidate(dentry, NULL))
            error = NULL;
out:
      return error;
}

static struct dentry *proc_pident_lookup(struct inode *dir, 
                               struct dentry *dentry,
                               const struct pid_entry *ents,
                               unsigned int nents)
{
      struct inode *inode;
      struct dentry *error;
      struct task_struct *task = get_proc_task(dir);
      const struct pid_entry *p, *last;

      error = ERR_PTR(-ENOENT);
      inode = NULL;

      if (!task)
            goto out_no_task;

      /*
       * Yes, it does not scale. And it should not. Don't add
       * new entries into /proc/<tgid>/ without very good reasons.
       */
      last = &ents[nents - 1];
      for (p = ents; p <= last; p++) {
            if (p->len != dentry->d_name.len)
                  continue;
            if (!memcmp(dentry->d_name.name, p->name, p->len))
                  break;
      }
      if (p > last)
            goto out;

      error = proc_pident_instantiate(dir, dentry, task, p);
out:
      put_task_struct(task);
out_no_task:
      return error;
}

static int proc_pident_fill_cache(struct file *filp, void *dirent,
      filldir_t filldir, struct task_struct *task, const struct pid_entry *p)
{
      return proc_fill_cache(filp, dirent, filldir, p->name, p->len,
                        proc_pident_instantiate, task, p);
}

static int proc_pident_readdir(struct file *filp,
            void *dirent, filldir_t filldir,
            const struct pid_entry *ents, unsigned int nents)
{
      int i;
      struct dentry *dentry = filp->f_path.dentry;
      struct inode *inode = dentry->d_inode;
      struct task_struct *task = get_proc_task(inode);
      const struct pid_entry *p, *last;
      ino_t ino;
      int ret;

      ret = -ENOENT;
      if (!task)
            goto out_no_task;

      ret = 0;
      i = filp->f_pos;
      switch (i) {
      case 0:
            ino = inode->i_ino;
            if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
                  goto out;
            i++;
            filp->f_pos++;
            /* fall through */
      case 1:
            ino = parent_ino(dentry);
            if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
                  goto out;
            i++;
            filp->f_pos++;
            /* fall through */
      default:
            i -= 2;
            if (i >= nents) {
                  ret = 1;
                  goto out;
            }
            p = ents + i;
            last = &ents[nents - 1];
            while (p <= last) {
                  if (proc_pident_fill_cache(filp, dirent, filldir, task, p) < 0)
                        goto out;
                  filp->f_pos++;
                  p++;
            }
      }

      ret = 1;
out:
      put_task_struct(task);
out_no_task:
      return ret;
}

#ifdef CONFIG_SECURITY
static ssize_t proc_pid_attr_read(struct file * file, char __user * buf,
                          size_t count, loff_t *ppos)
{
      struct inode * inode = file->f_path.dentry->d_inode;
      char *p = NULL;
      ssize_t length;
      struct task_struct *task = get_proc_task(inode);

      if (!task)
            return -ESRCH;

      length = security_getprocattr(task,
                              (char*)file->f_path.dentry->d_name.name,
                              &p);
      put_task_struct(task);
      if (length > 0)
            length = simple_read_from_buffer(buf, count, ppos, p, length);
      kfree(p);
      return length;
}

static ssize_t proc_pid_attr_write(struct file * file, const char __user * buf,
                           size_t count, loff_t *ppos)
{
      struct inode * inode = file->f_path.dentry->d_inode;
      char *page;
      ssize_t length;
      struct task_struct *task = get_proc_task(inode);

      length = -ESRCH;
      if (!task)
            goto out_no_task;
      if (count > PAGE_SIZE)
            count = PAGE_SIZE;

      /* No partial writes. */
      length = -EINVAL;
      if (*ppos != 0)
            goto out;

      length = -ENOMEM;
      page = (char*)__get_free_page(GFP_TEMPORARY);
      if (!page)
            goto out;

      length = -EFAULT;
      if (copy_from_user(page, buf, count))
            goto out_free;

      length = security_setprocattr(task,
                              (char*)file->f_path.dentry->d_name.name,
                              (void*)page, count);
out_free:
      free_page((unsigned long) page);
out:
      put_task_struct(task);
out_no_task:
      return length;
}

static const struct file_operations proc_pid_attr_operations = {
      .read       = proc_pid_attr_read,
      .write            = proc_pid_attr_write,
};

static const struct pid_entry attr_dir_stuff[] = {
      REG("current",    S_IRUGO|S_IWUGO, pid_attr),
      REG("prev",       S_IRUGO,       pid_attr),
      REG("exec",       S_IRUGO|S_IWUGO, pid_attr),
      REG("fscreate",   S_IRUGO|S_IWUGO, pid_attr),
      REG("keycreate",  S_IRUGO|S_IWUGO, pid_attr),
      REG("sockcreate", S_IRUGO|S_IWUGO, pid_attr),
};

static int proc_attr_dir_readdir(struct file * filp,
                       void * dirent, filldir_t filldir)
{
      return proc_pident_readdir(filp,dirent,filldir,
                           attr_dir_stuff,ARRAY_SIZE(attr_dir_stuff));
}

static const struct file_operations proc_attr_dir_operations = {
      .read       = generic_read_dir,
      .readdir    = proc_attr_dir_readdir,
};

static struct dentry *proc_attr_dir_lookup(struct inode *dir,
                        struct dentry *dentry, struct nameidata *nd)
{
      return proc_pident_lookup(dir, dentry,
                          attr_dir_stuff, ARRAY_SIZE(attr_dir_stuff));
}

static const struct inode_operations proc_attr_dir_inode_operations = {
      .lookup           = proc_attr_dir_lookup,
      .getattr    = pid_getattr,
      .setattr    = proc_setattr,
};

#endif

#if defined(USE_ELF_CORE_DUMP) && defined(CONFIG_ELF_CORE)
static ssize_t proc_coredump_filter_read(struct file *file, char __user *buf,
                               size_t count, loff_t *ppos)
{
      struct task_struct *task = get_proc_task(file->f_dentry->d_inode);
      struct mm_struct *mm;
      char buffer[PROC_NUMBUF];
      size_t len;
      int ret;

      if (!task)
            return -ESRCH;

      ret = 0;
      mm = get_task_mm(task);
      if (mm) {
            len = snprintf(buffer, sizeof(buffer), "%08lx\n",
                         ((mm->flags & MMF_DUMP_FILTER_MASK) >>
                        MMF_DUMP_FILTER_SHIFT));
            mmput(mm);
            ret = simple_read_from_buffer(buf, count, ppos, buffer, len);
      }

      put_task_struct(task);

      return ret;
}

static ssize_t proc_coredump_filter_write(struct file *file,
                                const char __user *buf,
                                size_t count,
                                loff_t *ppos)
{
      struct task_struct *task;
      struct mm_struct *mm;
      char buffer[PROC_NUMBUF], *end;
      unsigned int val;
      int ret;
      int i;
      unsigned long mask;

      ret = -EFAULT;
      memset(buffer, 0, sizeof(buffer));
      if (count > sizeof(buffer) - 1)
            count = sizeof(buffer) - 1;
      if (copy_from_user(buffer, buf, count))
            goto out_no_task;

      ret = -EINVAL;
      val = (unsigned int)simple_strtoul(buffer, &end, 0);
      if (*end == '\n')
            end++;
      if (end - buffer == 0)
            goto out_no_task;

      ret = -ESRCH;
      task = get_proc_task(file->f_dentry->d_inode);
      if (!task)
            goto out_no_task;

      ret = end - buffer;
      mm = get_task_mm(task);
      if (!mm)
            goto out_no_mm;

      for (i = 0, mask = 1; i < MMF_DUMP_FILTER_BITS; i++, mask <<= 1) {
            if (val & mask)
                  set_bit(i + MMF_DUMP_FILTER_SHIFT, &mm->flags);
            else
                  clear_bit(i + MMF_DUMP_FILTER_SHIFT, &mm->flags);
      }

      mmput(mm);
 out_no_mm:
      put_task_struct(task);
 out_no_task:
      return ret;
}

static const struct file_operations proc_coredump_filter_operations = {
      .read       = proc_coredump_filter_read,
      .write            = proc_coredump_filter_write,
};
#endif

/*
 * /proc/self:
 */
static int proc_self_readlink(struct dentry *dentry, char __user *buffer,
                        int buflen)
{
      char tmp[PROC_NUMBUF];
      sprintf(tmp, "%d", task_tgid_vnr(current));
      return vfs_readlink(dentry,buffer,buflen,tmp);
}

static void *proc_self_follow_link(struct dentry *dentry, struct nameidata *nd)
{
      char tmp[PROC_NUMBUF];
      sprintf(tmp, "%d", task_tgid_vnr(current));
      return ERR_PTR(vfs_follow_link(nd,tmp));
}

static const struct inode_operations proc_self_inode_operations = {
      .readlink   = proc_self_readlink,
      .follow_link      = proc_self_follow_link,
};

/*
 * proc base
 *
 * These are the directory entries in the root directory of /proc
 * that properly belong to the /proc filesystem, as they describe
 * describe something that is process related.
 */
static const struct pid_entry proc_base_stuff[] = {
      NOD("self", S_IFLNK|S_IRWXUGO,
            &proc_self_inode_operations, NULL, {}),
};

/*
 *    Exceptional case: normally we are not allowed to unhash a busy
 * directory. In this case, however, we can do it - no aliasing problems
 * due to the way we treat inodes.
 */
static int proc_base_revalidate(struct dentry *dentry, struct nameidata *nd)
{
      struct inode *inode = dentry->d_inode;
      struct task_struct *task = get_proc_task(inode);
      if (task) {
            put_task_struct(task);
            return 1;
      }
      d_drop(dentry);
      return 0;
}

static struct dentry_operations proc_base_dentry_operations =
{
      .d_revalidate     = proc_base_revalidate,
      .d_delete   = pid_delete_dentry,
};

static struct dentry *proc_base_instantiate(struct inode *dir,
      struct dentry *dentry, struct task_struct *task, const void *ptr)
{
      const struct pid_entry *p = ptr;
      struct inode *inode;
      struct proc_inode *ei;
      struct dentry *error = ERR_PTR(-EINVAL);

      /* Allocate the inode */
      error = ERR_PTR(-ENOMEM);
      inode = new_inode(dir->i_sb);
      if (!inode)
            goto out;

      /* Initialize the inode */
      ei = PROC_I(inode);
      inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;

      /*
       * grab the reference to the task.
       */
      ei->pid = get_task_pid(task, PIDTYPE_PID);
      if (!ei->pid)
            goto out_iput;

      inode->i_uid = 0;
      inode->i_gid = 0;
      inode->i_mode = p->mode;
      if (S_ISDIR(inode->i_mode))
            inode->i_nlink = 2;
      if (S_ISLNK(inode->i_mode))
            inode->i_size = 64;
      if (p->iop)
            inode->i_op = p->iop;
      if (p->fop)
            inode->i_fop = p->fop;
      ei->op = p->op;
      dentry->d_op = &proc_base_dentry_operations;
      d_add(dentry, inode);
      error = NULL;
out:
      return error;
out_iput:
      iput(inode);
      goto out;
}

static struct dentry *proc_base_lookup(struct inode *dir, struct dentry *dentry)
{
      struct dentry *error;
      struct task_struct *task = get_proc_task(dir);
      const struct pid_entry *p, *last;

      error = ERR_PTR(-ENOENT);

      if (!task)
            goto out_no_task;

      /* Lookup the directory entry */
      last = &proc_base_stuff[ARRAY_SIZE(proc_base_stuff) - 1];
      for (p = proc_base_stuff; p <= last; p++) {
            if (p->len != dentry->d_name.len)
                  continue;
            if (!memcmp(dentry->d_name.name, p->name, p->len))
                  break;
      }
      if (p > last)
            goto out;

      error = proc_base_instantiate(dir, dentry, task, p);

out:
      put_task_struct(task);
out_no_task:
      return error;
}

static int proc_base_fill_cache(struct file *filp, void *dirent,
      filldir_t filldir, struct task_struct *task, const struct pid_entry *p)
{
      return proc_fill_cache(filp, dirent, filldir, p->name, p->len,
                        proc_base_instantiate, task, p);
}

#ifdef CONFIG_TASK_IO_ACCOUNTING
static int proc_pid_io_accounting(struct task_struct *task, char *buffer)
{
      return sprintf(buffer,
#ifdef CONFIG_TASK_XACCT
                  "rchar: %llu\n"
                  "wchar: %llu\n"
                  "syscr: %llu\n"
                  "syscw: %llu\n"
#endif
                  "read_bytes: %llu\n"
                  "write_bytes: %llu\n"
                  "cancelled_write_bytes: %llu\n",
#ifdef CONFIG_TASK_XACCT
                  (unsigned long long)task->rchar,
                  (unsigned long long)task->wchar,
                  (unsigned long long)task->syscr,
                  (unsigned long long)task->syscw,
#endif
                  (unsigned long long)task->ioac.read_bytes,
                  (unsigned long long)task->ioac.write_bytes,
                  (unsigned long long)task->ioac.cancelled_write_bytes);
}
#endif

/*
 * Thread groups
 */
static const struct file_operations proc_task_operations;
static const struct inode_operations proc_task_inode_operations;

static const struct pid_entry tgid_base_stuff[] = {
      DIR("task",       S_IRUGO|S_IXUGO, task),
      DIR("fd",         S_IRUSR|S_IXUSR, fd),
      DIR("fdinfo",     S_IRUSR|S_IXUSR, fdinfo),
      REG("environ",    S_IRUSR, environ),
      INF("auxv",       S_IRUSR, pid_auxv),
      INF("status",     S_IRUGO, pid_status),
      INF("limits",       S_IRUSR, pid_limits),
#ifdef CONFIG_SCHED_DEBUG
      REG("sched",      S_IRUGO|S_IWUSR, pid_sched),
#endif
      INF("cmdline",    S_IRUGO, pid_cmdline),
      INF("stat",       S_IRUGO, tgid_stat),
      INF("statm",      S_IRUGO, pid_statm),
      REG("maps",       S_IRUGO, maps),
#ifdef CONFIG_NUMA
      REG("numa_maps",  S_IRUGO, numa_maps),
#endif
      REG("mem",        S_IRUSR|S_IWUSR, mem),
      LNK("cwd",        cwd),
      LNK("root",       root),
      LNK("exe",        exe),
      REG("mounts",     S_IRUGO, mounts),
      REG("mountstats", S_IRUSR, mountstats),
#ifdef CONFIG_MMU
      REG("clear_refs", S_IWUSR, clear_refs),
      REG("smaps",      S_IRUGO, smaps),
#endif
#ifdef CONFIG_SECURITY
      DIR("attr",       S_IRUGO|S_IXUGO, attr_dir),
#endif
#ifdef CONFIG_KALLSYMS
      INF("wchan",      S_IRUGO, pid_wchan),
#endif
#ifdef CONFIG_SCHEDSTATS
      INF("schedstat",  S_IRUGO, pid_schedstat),
#endif
#ifdef CONFIG_PROC_PID_CPUSET
      REG("cpuset",     S_IRUGO, cpuset),
#endif
#ifdef CONFIG_CGROUPS
      REG("cgroup",  S_IRUGO, cgroup),
#endif
      INF("oom_score",  S_IRUGO, oom_score),
      REG("oom_adj",    S_IRUGO|S_IWUSR, oom_adjust),
#ifdef CONFIG_AUDITSYSCALL
      REG("loginuid",   S_IWUSR|S_IRUGO, loginuid),
#endif
#ifdef CONFIG_FAULT_INJECTION
      REG("make-it-fail", S_IRUGO|S_IWUSR, fault_inject),
#endif
#if defined(USE_ELF_CORE_DUMP) && defined(CONFIG_ELF_CORE)
      REG("coredump_filter", S_IRUGO|S_IWUSR, coredump_filter),
#endif
#ifdef CONFIG_TASK_IO_ACCOUNTING
      INF("io",   S_IRUGO, pid_io_accounting),
#endif
};

static int proc_tgid_base_readdir(struct file * filp,
                       void * dirent, filldir_t filldir)
{
      return proc_pident_readdir(filp,dirent,filldir,
                           tgid_base_stuff,ARRAY_SIZE(tgid_base_stuff));
}

static const struct file_operations proc_tgid_base_operations = {
      .read       = generic_read_dir,
      .readdir    = proc_tgid_base_readdir,
};

static struct dentry *proc_tgid_base_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd){
      return proc_pident_lookup(dir, dentry,
                          tgid_base_stuff, ARRAY_SIZE(tgid_base_stuff));
}

static const struct inode_operations proc_tgid_base_inode_operations = {
      .lookup           = proc_tgid_base_lookup,
      .getattr    = pid_getattr,
      .setattr    = proc_setattr,
};

static void proc_flush_task_mnt(struct vfsmount *mnt, pid_t pid, pid_t tgid)
{
      struct dentry *dentry, *leader, *dir;
      char buf[PROC_NUMBUF];
      struct qstr name;

      name.name = buf;
      name.len = snprintf(buf, sizeof(buf), "%d", pid);
      dentry = d_hash_and_lookup(mnt->mnt_root, &name);
      if (dentry) {
            shrink_dcache_parent(dentry);
            d_drop(dentry);
            dput(dentry);
      }

      if (tgid == 0)
            goto out;

      name.name = buf;
      name.len = snprintf(buf, sizeof(buf), "%d", tgid);
      leader = d_hash_and_lookup(mnt->mnt_root, &name);
      if (!leader)
            goto out;

      name.name = "task";
      name.len = strlen(name.name);
      dir = d_hash_and_lookup(leader, &name);
      if (!dir)
            goto out_put_leader;

      name.name = buf;
      name.len = snprintf(buf, sizeof(buf), "%d", pid);
      dentry = d_hash_and_lookup(dir, &name);
      if (dentry) {
            shrink_dcache_parent(dentry);
            d_drop(dentry);
            dput(dentry);
      }

      dput(dir);
out_put_leader:
      dput(leader);
out:
      return;
}

/**
 * proc_flush_task -  Remove dcache entries for @task from the /proc dcache.
 * @task: task that should be flushed.
 *
 * When flushing dentries from proc, one needs to flush them from global
 * proc (proc_mnt) and from all the namespaces' procs this task was seen
 * in. This call is supposed to do all of this job.
 *
 * Looks in the dcache for
 * /proc/@pid
 * /proc/@tgid/task/@pid
 * if either directory is present flushes it and all of it'ts children
 * from the dcache.
 *
 * It is safe and reasonable to cache /proc entries for a task until
 * that task exits.  After that they just clog up the dcache with
 * useless entries, possibly causing useful dcache entries to be
 * flushed instead.  This routine is proved to flush those useless
 * dcache entries at process exit time.
 *
 * NOTE: This routine is just an optimization so it does not guarantee
 *       that no dcache entries will exist at process exit time it
 *       just makes it very unlikely that any will persist.
 */

void proc_flush_task(struct task_struct *task)
{
      int i;
      struct pid *pid, *tgid = NULL;
      struct upid *upid;

      pid = task_pid(task);
      if (thread_group_leader(task))
            tgid = task_tgid(task);

      for (i = 0; i <= pid->level; i++) {
            upid = &pid->numbers[i];
            proc_flush_task_mnt(upid->ns->proc_mnt, upid->nr,
                  tgid ? tgid->numbers[i].nr : 0);
      }

      upid = &pid->numbers[pid->level];
      if (upid->nr == 1)
            pid_ns_release_proc(upid->ns);
}

static struct dentry *proc_pid_instantiate(struct inode *dir,
                                 struct dentry * dentry,
                                 struct task_struct *task, const void *ptr)
{
      struct dentry *error = ERR_PTR(-ENOENT);
      struct inode *inode;

      inode = proc_pid_make_inode(dir->i_sb, task);
      if (!inode)
            goto out;

      inode->i_mode = S_IFDIR|S_IRUGO|S_IXUGO;
      inode->i_op = &proc_tgid_base_inode_operations;
      inode->i_fop = &proc_tgid_base_operations;
      inode->i_flags|=S_IMMUTABLE;
      inode->i_nlink = 5;
#ifdef CONFIG_SECURITY
      inode->i_nlink += 1;
#endif

      dentry->d_op = &pid_dentry_operations;

      d_add(dentry, inode);
      /* Close the race of the process dying before we return the dentry */
      if (pid_revalidate(dentry, NULL))
            error = NULL;
out:
      return error;
}

struct dentry *proc_pid_lookup(struct inode *dir, struct dentry * dentry, struct nameidata *nd)
{
      struct dentry *result = ERR_PTR(-ENOENT);
      struct task_struct *task;
      unsigned tgid;
      struct pid_namespace *ns;

      result = proc_base_lookup(dir, dentry);
      if (!IS_ERR(result) || PTR_ERR(result) != -ENOENT)
            goto out;

      tgid = name_to_int(dentry);
      if (tgid == ~0U)
            goto out;

      ns = dentry->d_sb->s_fs_info;
      rcu_read_lock();
      task = find_task_by_pid_ns(tgid, ns);
      if (task)
            get_task_struct(task);
      rcu_read_unlock();
      if (!task)
            goto out;

      result = proc_pid_instantiate(dir, dentry, task, NULL);
      put_task_struct(task);
out:
      return result;
}

/*
 * Find the first task with tgid >= tgid
 *
 */
struct tgid_iter {
      unsigned int tgid;
      struct task_struct *task;
};
static struct tgid_iter next_tgid(struct pid_namespace *ns, struct tgid_iter iter)
{
      struct pid *pid;

      if (iter.task)
            put_task_struct(iter.task);
      rcu_read_lock();
retry:
      iter.task = NULL;
      pid = find_ge_pid(iter.tgid, ns);
      if (pid) {
            iter.tgid = pid_nr_ns(pid, ns);
            iter.task = pid_task(pid, PIDTYPE_PID);
            /* What we to know is if the pid we have find is the
             * pid of a thread_group_leader.  Testing for task
             * being a thread_group_leader is the obvious thing
             * todo but there is a window when it fails, due to
             * the pid transfer logic in de_thread.
             *
             * So we perform the straight forward test of seeing
             * if the pid we have found is the pid of a thread
             * group leader, and don't worry if the task we have
             * found doesn't happen to be a thread group leader.
             * As we don't care in the case of readdir.
             */
            if (!iter.task || !has_group_leader_pid(iter.task)) {
                  iter.tgid += 1;
                  goto retry;
            }
            get_task_struct(iter.task);
      }
      rcu_read_unlock();
      return iter;
}

#define TGID_OFFSET (FIRST_PROCESS_ENTRY + ARRAY_SIZE(proc_base_stuff))

static int proc_pid_fill_cache(struct file *filp, void *dirent, filldir_t filldir,
      struct tgid_iter iter)
{
      char name[PROC_NUMBUF];
      int len = snprintf(name, sizeof(name), "%d", iter.tgid);
      return proc_fill_cache(filp, dirent, filldir, name, len,
                        proc_pid_instantiate, iter.task, NULL);
}

/* for the /proc/ directory itself, after non-process stuff has been done */
int proc_pid_readdir(struct file * filp, void * dirent, filldir_t filldir)
{
      unsigned int nr = filp->f_pos - FIRST_PROCESS_ENTRY;
      struct task_struct *reaper = get_proc_task(filp->f_path.dentry->d_inode);
      struct tgid_iter iter;
      struct pid_namespace *ns;

      if (!reaper)
            goto out_no_task;

      for (; nr < ARRAY_SIZE(proc_base_stuff); filp->f_pos++, nr++) {
            const struct pid_entry *p = &proc_base_stuff[nr];
            if (proc_base_fill_cache(filp, dirent, filldir, reaper, p) < 0)
                  goto out;
      }

      ns = filp->f_dentry->d_sb->s_fs_info;
      iter.task = NULL;
      iter.tgid = filp->f_pos - TGID_OFFSET;
      for (iter = next_tgid(ns, iter);
           iter.task;
           iter.tgid += 1, iter = next_tgid(ns, iter)) {
            filp->f_pos = iter.tgid + TGID_OFFSET;
            if (proc_pid_fill_cache(filp, dirent, filldir, iter) < 0) {
                  put_task_struct(iter.task);
                  goto out;
            }
      }
      filp->f_pos = PID_MAX_LIMIT + TGID_OFFSET;
out:
      put_task_struct(reaper);
out_no_task:
      return 0;
}

/*
 * Tasks
 */
static const struct pid_entry tid_base_stuff[] = {
      DIR("fd",        S_IRUSR|S_IXUSR, fd),
      DIR("fdinfo",    S_IRUSR|S_IXUSR, fdinfo),
      REG("environ",   S_IRUSR, environ),
      INF("auxv",      S_IRUSR, pid_auxv),
      INF("status",    S_IRUGO, pid_status),
      INF("limits",      S_IRUSR, pid_limits),
#ifdef CONFIG_SCHED_DEBUG
      REG("sched",     S_IRUGO|S_IWUSR, pid_sched),
#endif
      INF("cmdline",   S_IRUGO, pid_cmdline),
      INF("stat",      S_IRUGO, tid_stat),
      INF("statm",     S_IRUGO, pid_statm),
      REG("maps",      S_IRUGO, maps),
#ifdef CONFIG_NUMA
      REG("numa_maps", S_IRUGO, numa_maps),
#endif
      REG("mem",       S_IRUSR|S_IWUSR, mem),
      LNK("cwd",       cwd),
      LNK("root",      root),
      LNK("exe",       exe),
      REG("mounts",    S_IRUGO, mounts),
#ifdef CONFIG_MMU
      REG("clear_refs", S_IWUSR, clear_refs),
      REG("smaps",     S_IRUGO, smaps),
#endif
#ifdef CONFIG_SECURITY
      DIR("attr",      S_IRUGO|S_IXUGO, attr_dir),
#endif
#ifdef CONFIG_KALLSYMS
      INF("wchan",     S_IRUGO, pid_wchan),
#endif
#ifdef CONFIG_SCHEDSTATS
      INF("schedstat", S_IRUGO, pid_schedstat),
#endif
#ifdef CONFIG_PROC_PID_CPUSET
      REG("cpuset",    S_IRUGO, cpuset),
#endif
#ifdef CONFIG_CGROUPS
      REG("cgroup",  S_IRUGO, cgroup),
#endif
      INF("oom_score", S_IRUGO, oom_score),
      REG("oom_adj",   S_IRUGO|S_IWUSR, oom_adjust),
#ifdef CONFIG_AUDITSYSCALL
      REG("loginuid",  S_IWUSR|S_IRUGO, loginuid),
#endif
#ifdef CONFIG_FAULT_INJECTION
      REG("make-it-fail", S_IRUGO|S_IWUSR, fault_inject),
#endif
};

static int proc_tid_base_readdir(struct file * filp,
                       void * dirent, filldir_t filldir)
{
      return proc_pident_readdir(filp,dirent,filldir,
                           tid_base_stuff,ARRAY_SIZE(tid_base_stuff));
}

static struct dentry *proc_tid_base_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd){
      return proc_pident_lookup(dir, dentry,
                          tid_base_stuff, ARRAY_SIZE(tid_base_stuff));
}

static const struct file_operations proc_tid_base_operations = {
      .read       = generic_read_dir,
      .readdir    = proc_tid_base_readdir,
};

static const struct inode_operations proc_tid_base_inode_operations = {
      .lookup           = proc_tid_base_lookup,
      .getattr    = pid_getattr,
      .setattr    = proc_setattr,
};

static struct dentry *proc_task_instantiate(struct inode *dir,
      struct dentry *dentry, struct task_struct *task, const void *ptr)
{
      struct dentry *error = ERR_PTR(-ENOENT);
      struct inode *inode;
      inode = proc_pid_make_inode(dir->i_sb, task);

      if (!inode)
            goto out;
      inode->i_mode = S_IFDIR|S_IRUGO|S_IXUGO;
      inode->i_op = &proc_tid_base_inode_operations;
      inode->i_fop = &proc_tid_base_operations;
      inode->i_flags|=S_IMMUTABLE;
      inode->i_nlink = 4;
#ifdef CONFIG_SECURITY
      inode->i_nlink += 1;
#endif

      dentry->d_op = &pid_dentry_operations;

      d_add(dentry, inode);
      /* Close the race of the process dying before we return the dentry */
      if (pid_revalidate(dentry, NULL))
            error = NULL;
out:
      return error;
}

static struct dentry *proc_task_lookup(struct inode *dir, struct dentry * dentry, struct nameidata *nd)
{
      struct dentry *result = ERR_PTR(-ENOENT);
      struct task_struct *task;
      struct task_struct *leader = get_proc_task(dir);
      unsigned tid;
      struct pid_namespace *ns;

      if (!leader)
            goto out_no_task;

      tid = name_to_int(dentry);
      if (tid == ~0U)
            goto out;

      ns = dentry->d_sb->s_fs_info;
      rcu_read_lock();
      task = find_task_by_pid_ns(tid, ns);
      if (task)
            get_task_struct(task);
      rcu_read_unlock();
      if (!task)
            goto out;
      if (!same_thread_group(leader, task))
            goto out_drop_task;

      result = proc_task_instantiate(dir, dentry, task, NULL);
out_drop_task:
      put_task_struct(task);
out:
      put_task_struct(leader);
out_no_task:
      return result;
}

/*
 * Find the first tid of a thread group to return to user space.
 *
 * Usually this is just the thread group leader, but if the users
 * buffer was too small or there was a seek into the middle of the
 * directory we have more work todo.
 *
 * In the case of a short read we start with find_task_by_pid.
 *
 * In the case of a seek we start with the leader and walk nr
 * threads past it.
 */
static struct task_struct *first_tid(struct task_struct *leader,
            int tid, int nr, struct pid_namespace *ns)
{
      struct task_struct *pos;

      rcu_read_lock();
      /* Attempt to start with the pid of a thread */
      if (tid && (nr > 0)) {
            pos = find_task_by_pid_ns(tid, ns);
            if (pos && (pos->group_leader == leader))
                  goto found;
      }

      /* If nr exceeds the number of threads there is nothing todo */
      pos = NULL;
      if (nr && nr >= get_nr_threads(leader))
            goto out;

      /* If we haven't found our starting place yet start
       * with the leader and walk nr threads forward.
       */
      for (pos = leader; nr > 0; --nr) {
            pos = next_thread(pos);
            if (pos == leader) {
                  pos = NULL;
                  goto out;
            }
      }
found:
      get_task_struct(pos);
out:
      rcu_read_unlock();
      return pos;
}

/*
 * Find the next thread in the thread list.
 * Return NULL if there is an error or no next thread.
 *
 * The reference to the input task_struct is released.
 */
static struct task_struct *next_tid(struct task_struct *start)
{
      struct task_struct *pos = NULL;
      rcu_read_lock();
      if (pid_alive(start)) {
            pos = next_thread(start);
            if (thread_group_leader(pos))
                  pos = NULL;
            else
                  get_task_struct(pos);
      }
      rcu_read_unlock();
      put_task_struct(start);
      return pos;
}

static int proc_task_fill_cache(struct file *filp, void *dirent, filldir_t filldir,
      struct task_struct *task, int tid)
{
      char name[PROC_NUMBUF];
      int len = snprintf(name, sizeof(name), "%d", tid);
      return proc_fill_cache(filp, dirent, filldir, name, len,
                        proc_task_instantiate, task, NULL);
}

/* for the /proc/TGID/task/ directories */
static int proc_task_readdir(struct file * filp, void * dirent, filldir_t filldir)
{
      struct dentry *dentry = filp->f_path.dentry;
      struct inode *inode = dentry->d_inode;
      struct task_struct *leader = NULL;
      struct task_struct *task;
      int retval = -ENOENT;
      ino_t ino;
      int tid;
      unsigned long pos = filp->f_pos;  /* avoiding "long long" filp->f_pos */
      struct pid_namespace *ns;

      task = get_proc_task(inode);
      if (!task)
            goto out_no_task;
      rcu_read_lock();
      if (pid_alive(task)) {
            leader = task->group_leader;
            get_task_struct(leader);
      }
      rcu_read_unlock();
      put_task_struct(task);
      if (!leader)
            goto out_no_task;
      retval = 0;

      switch (pos) {
      case 0:
            ino = inode->i_ino;
            if (filldir(dirent, ".", 1, pos, ino, DT_DIR) < 0)
                  goto out;
            pos++;
            /* fall through */
      case 1:
            ino = parent_ino(dentry);
            if (filldir(dirent, "..", 2, pos, ino, DT_DIR) < 0)
                  goto out;
            pos++;
            /* fall through */
      }

      /* f_version caches the tgid value that the last readdir call couldn't
       * return. lseek aka telldir automagically resets f_version to 0.
       */
      ns = filp->f_dentry->d_sb->s_fs_info;
      tid = (int)filp->f_version;
      filp->f_version = 0;
      for (task = first_tid(leader, tid, pos - 2, ns);
           task;
           task = next_tid(task), pos++) {
            tid = task_pid_nr_ns(task, ns);
            if (proc_task_fill_cache(filp, dirent, filldir, task, tid) < 0) {
                  /* returning this tgid failed, save it as the first
                   * pid for the next readir call */
                  filp->f_version = (u64)tid;
                  put_task_struct(task);
                  break;
            }
      }
out:
      filp->f_pos = pos;
      put_task_struct(leader);
out_no_task:
      return retval;
}

static int proc_task_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
{
      struct inode *inode = dentry->d_inode;
      struct task_struct *p = get_proc_task(inode);
      generic_fillattr(inode, stat);

      if (p) {
            rcu_read_lock();
            stat->nlink += get_nr_threads(p);
            rcu_read_unlock();
            put_task_struct(p);
      }

      return 0;
}

static const struct inode_operations proc_task_inode_operations = {
      .lookup           = proc_task_lookup,
      .getattr    = proc_task_getattr,
      .setattr    = proc_setattr,
};

static const struct file_operations proc_task_operations = {
      .read       = generic_read_dir,
      .readdir    = proc_task_readdir,
};

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