LXR linux/fs/proc/thread

   1#include <linux/sched.h>
   2#include <linux/namei.h>
   3#include <linux/slab.h>
   4#include <linux/pid_namespace.h>
   5#include "internal.h"
   6
   7/*
   8 * /proc/thread_self:
   9 */
  10static int proc_thread_self_readlink(struct dentry *dentry, char __user *buffer,
  11                              int buflen)
  12{
  13        struct pid_namespace *ns = dentry->d_sb->s_fs_info;
  14        pid_t tgid = task_tgid_nr_ns(current, ns);
  15        pid_t pid = task_pid_nr_ns(current, ns);
  16        char tmp[PROC_NUMBUF + 6 + PROC_NUMBUF];
  17        if (!pid)
  18                return -ENOENT;
  19        sprintf(tmp, "%d/task/%d", tgid, pid);
  20        return readlink_copy(buffer, buflen, tmp);
  21}
  22
  23static void *proc_thread_self_follow_link(struct dentry *dentry, struct nameidata *nd)
  24{
  25        struct pid_namespace *ns = dentry->d_sb->s_fs_info;
  26        pid_t tgid = task_tgid_nr_ns(current, ns);
  27        pid_t pid = task_pid_nr_ns(current, ns);
  28        char *name = ERR_PTR(-ENOENT);
  29        if (pid) {
  30                name = kmalloc(PROC_NUMBUF + 6 + PROC_NUMBUF, GFP_KERNEL);
  31                if (!name)
  32                        name = ERR_PTR(-ENOMEM);
  33                else
  34                        sprintf(name, "%d/task/%d", tgid, pid);
  35        }
  36        nd_set_link(nd, name);
  37        return NULL;
  38}
  39
  40static const struct inode_operations proc_thread_self_inode_operations = {
  41        .readlink       = proc_thread_self_readlink,
  42        .follow_link    = proc_thread_self_follow_link,
  43        .put_link       = kfree_put_link,
  44};
  45
  46static unsigned thread_self_inum;
  47
  48int proc_setup_thread_self(struct super_block *s)
  49{
  50        struct inode *root_inode = s->s_root->d_inode;
  51        struct pid_namespace *ns = s->s_fs_info;
  52        struct dentry *thread_self;
  53
  54        mutex_lock(&root_inode->i_mutex);
  55        thread_self = d_alloc_name(s->s_root, "thread-self");
  56        if (thread_self) {
  57                struct inode *inode = new_inode_pseudo(s);
  58                if (inode) {
  59                        inode->i_ino = thread_self_inum;
  60                        inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
  61                        inode->i_mode = S_IFLNK | S_IRWXUGO;
  62                        inode->i_uid = GLOBAL_ROOT_UID;
  63                        inode->i_gid = GLOBAL_ROOT_GID;
  64                        inode->i_op = &proc_thread_self_inode_operations;
  65                        d_add(thread_self, inode);
  66                } else {
  67                        dput(thread_self);
  68                        thread_self = ERR_PTR(-ENOMEM);
  69                }
  70        } else {
  71                thread_self = ERR_PTR(-ENOMEM);
  72        }
  73        mutex_unlock(&root_inode->i_mutex);
  74        if (IS_ERR(thread_self)) {
  75                pr_err("proc_fill_super: can't allocate /proc/thread_self\n");
  76                return PTR_ERR(thread_self);
  77        }
  78        ns->proc_thread_self = thread_self;
  79        return 0;
  80}
  81
  82void __init proc_thread_self_init(void)
  83{
  84        proc_alloc_inum(&thread_self_inum);
  85}
  86