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/* -*- linux-c -*-
*
* /proc command channels
* Copyright (C) 2007-2009 Red Hat Inc.
*
* This file is part of systemtap, and is free software. You can
* redistribute it and/or modify it under the terms of the GNU General
* Public License (GPL); either version 2, or (at your option) any
* later version.
*/
/* The maximum number of files AND directories that can be opened.
* It would be great if the translator would emit this based on the actual
* number of needed files.
*/
#ifndef _STP_PROCFS_C_
#define _STP_PROCFS_C_
#ifndef STP_MAX_PROCFS_FILES
#define STP_MAX_PROCFS_FILES 16
#endif
static int _stp_num_pde = 0;
static struct proc_dir_entry *_stp_pde[STP_MAX_PROCFS_FILES];
static struct proc_dir_entry *_stp_procfs_files[STP_MAX_PROCFS_FILES];
static struct proc_dir_entry *_stp_proc_stap = NULL;
static struct proc_dir_entry *_stp_proc_root = NULL;
static void _stp_close_procfs(void);
// 2.6.24 fixed proc_dir_entry refcounting.
#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,24)
#define LAST_ENTRY_COUNT 0
#else
#define LAST_ENTRY_COUNT 1
#endif
/*
* Removes /proc/systemtap/{module_name} and /proc/systemtap (if empty)
*/
static void _stp_rmdir_proc_module(void)
{
if (!_stp_lock_transport_dir()) {
errk("Unable to lock transport directory.\n");
return;
}
if (_stp_proc_root && _stp_proc_root->subdir == NULL) {
if (atomic_read(&_stp_proc_root->count) != LAST_ENTRY_COUNT)
_stp_warn("Removal of /proc/systemtap/%s\nis deferred until it is no longer in use.\n"
"Systemtap module removal will block.\n", THIS_MODULE->name);
remove_proc_entry(THIS_MODULE->name, _stp_proc_stap);
_stp_proc_root = NULL;
}
if (_stp_proc_stap && _stp_proc_stap->subdir == NULL) {
/* Important! Do not attempt removal of /proc/systemtap */
/* if in use. This will put the PDE in deleted state */
/* pending usage count dropping to 0. During this time, */
/* path_lookup() will still find it and allow new */
/* modules to use it, even though it will not show up */
/* in directory listings. */
if (atomic_read(&_stp_proc_stap->count) == 0) {
remove_proc_entry("systemtap", NULL);
_stp_proc_stap = NULL;
}
}
_stp_unlock_transport_dir();
}
/*
* Safely creates /proc/systemtap (if necessary) and
* /proc/systemtap/{module_name}.
*/
static int _stp_mkdir_proc_module(void)
{
if (_stp_proc_root == NULL) {
struct nameidata nd;
if (!_stp_lock_transport_dir()) {
errk("Unable to lock transport directory.\n");
goto done;
}
/* We use path_lookup() because there is no lookup */
/* function for procfs we can call directly. And */
/* proc_mkdir() will always succeed, creating multiple */
/* directory entries, all with the same name. */
if (path_lookup("/proc/systemtap", 0, &nd)) {
/* doesn't exist, so create it */
_stp_proc_stap = proc_mkdir ("systemtap", NULL);
if (_stp_proc_stap == NULL) {
_stp_unlock_transport_dir();
goto done;
}
} else {
#ifdef STAPCONF_NAMEIDATA_CLEANUP
_stp_proc_stap = PDE(nd.path.dentry->d_inode);
path_put (&nd.path);
#else
_stp_proc_stap = PDE(nd.dentry->d_inode);
path_release (&nd);
#endif
}
_stp_proc_root = proc_mkdir(THIS_MODULE->name, _stp_proc_stap);
#ifdef AUTOCONF_PROCFS_OWNER
if (_stp_proc_root != NULL)
_stp_proc_root->owner = THIS_MODULE;
#endif
_stp_unlock_transport_dir();
}
done:
return (_stp_proc_root) ? 1 : 0;
}
/*
* This checks our local cache to see if we already made the dir.
*/
static struct proc_dir_entry *_stp_procfs_lookup(const char *dir, struct proc_dir_entry *parent)
{
int i;
for (i = 0; i <_stp_num_pde; i++) {
struct proc_dir_entry *pde = _stp_pde[i];
if (pde->parent == parent && !strcmp(dir, pde->name))
return pde;
}
return NULL;
}
static int _stp_create_procfs(const char *path, int num,
const struct file_operations *fops)
{
const char *p;
char *next;
struct proc_dir_entry *last_dir, *de;
if (num >= STP_MAX_PROCFS_FILES) {
_stp_error("Requested file number %d is larger than max (%d)\n",
num, STP_MAX_PROCFS_FILES);
return -1;
}
_stp_mkdir_proc_module();
last_dir = _stp_proc_root;
/* if no path, use default one */
if (strlen(path) == 0)
p = "command";
else
p = path;
while ((next = strchr(p, '/'))) {
if (_stp_num_pde == STP_MAX_PROCFS_FILES)
goto too_many;
*next = 0;
de = _stp_procfs_lookup(p, last_dir);
if (de == NULL) {
last_dir = proc_mkdir(p, last_dir);
if (!last_dir) {
_stp_error("Could not create directory \"%s\"\n", p);
goto err;
}
_stp_pde[_stp_num_pde++] = last_dir;
#ifdef AUTOCONF_PROCFS_OWNER
last_dir->owner = THIS_MODULE;
#endif
last_dir->uid = _stp_uid;
last_dir->gid = _stp_gid;
} else {
if (!S_ISDIR(de->mode)) {
_stp_error("Could not create directory \"%s\"\n", p);
goto err;
}
last_dir = de;
}
p = next + 1;
}
if (_stp_num_pde == STP_MAX_PROCFS_FILES)
goto too_many;
de = proc_create(p, 0600, last_dir, fops);
if (de == NULL) {
_stp_error("Could not create file \"%s\" in path \"%s\"\n", p, path);
goto err;
}
#ifdef AUTOCONF_PROCFS_OWNER
de->owner = THIS_MODULE;
#endif
de->uid = _stp_uid;
de->gid = _stp_gid;
_stp_pde[_stp_num_pde++] = de;
_stp_procfs_files[num] = de;
return 0;
too_many:
_stp_error("Attempted to open too many procfs files. Maximum is %d\n", STP_MAX_PROCFS_FILES);
err:
_stp_close_procfs();
return -1;
}
static void _stp_close_procfs(void)
{
int i;
for (i = _stp_num_pde-1; i >= 0; i--) {
struct proc_dir_entry *pde = _stp_pde[i];
remove_proc_entry(pde->name, pde->parent);
}
_stp_num_pde = 0;
_stp_rmdir_proc_module();
}
#endif /* _STP_PROCFS_C_ */
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