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/* -*- linux-c -*-
*
* debugfs functions
* Copyright (C) 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.
*/
#include <linux/debugfs.h>
#include "transport.h"
#include "../uidgid_compatibility.h"
/* Always returns zero, we just push all messages on the _stp_ctl_ready_q. */
inline static int _stp_debugfs_ctl_write_fs(int type, void *data, unsigned len)
{
return 0;
}
static struct dentry *__stp_debugfs_root_dir = NULL; // DEBUGFS/systemtap/
static struct dentry *__stp_debugfs_module_dir = NULL; // DEBUGFS/systemtap/MODULE/
static struct dentry *_stp_cmd_file = NULL; // DEBUGFS/systemtap/MODULE/.cmd
static int _stp_debugfs_register_ctl_channel_fs(void)
{
struct dentry *module_dir = _stp_debugfs_get_module_dir();
if (module_dir == NULL) {
errk("no module directory found.\n");
return -1;
}
/* create [debugfs]/systemtap/module_name/.cmd */
_stp_cmd_file = debugfs_create_file(".cmd", 0600, module_dir,
NULL, &_stp_ctl_fops_cmd);
if (_stp_cmd_file == NULL) {
errk("Error creating systemtap debugfs entries.\n");
return -1;
}
else if (IS_ERR(_stp_cmd_file)) {
_stp_cmd_file = NULL;
errk("Error creating systemtap debugfs entries: %ld\n",
-PTR_ERR(_stp_cmd_file));
return -1;
}
_stp_cmd_file->d_inode->i_uid = KUIDT_INIT(_stp_uid);
_stp_cmd_file->d_inode->i_gid = KGIDT_INIT(_stp_gid);
return 0;
}
static void _stp_debugfs_unregister_ctl_channel_fs(void)
{
if (_stp_cmd_file)
debugfs_remove(_stp_cmd_file);
}
static int _stp_debugfs_transport_fs_init(const char *module_name)
{
struct dentry *root_dir;
dbug_trans(1, "entry\n");
if (module_name == NULL)
return -1;
if (!_stp_lock_transport_dir()) {
errk("Couldn't lock transport directory.\n");
return -1;
}
root_dir = _stp_debugfs_get_root_dir();
if (root_dir == NULL) {
_stp_unlock_transport_dir();
return -1;
}
__stp_debugfs_module_dir = debugfs_create_dir(module_name, root_dir);
if (!__stp_debugfs_module_dir) {
errk("Could not create module directory \"%s\"\n",
module_name);
_stp_debugfs_remove_root_dir();
_stp_unlock_transport_dir();
return -1;
}
else if (IS_ERR(__stp_debugfs_module_dir)) {
errk("Could not create module directory \"%s\", error %ld\n",
module_name, -PTR_ERR(__stp_debugfs_module_dir));
_stp_debugfs_remove_root_dir();
_stp_unlock_transport_dir();
return -1;
}
if (_stp_transport_data_fs_init() != 0) {
debugfs_remove(__stp_debugfs_module_dir);
__stp_debugfs_module_dir = NULL;
_stp_debugfs_remove_root_dir();
_stp_unlock_transport_dir();
return -1;
}
_stp_unlock_transport_dir();
dbug_trans(1, "returning 0\n");
return 0;
}
static void _stp_debugfs_transport_fs_close(void)
{
dbug_trans(1, "stp_transport_fs_close\n");
_stp_transport_data_fs_close();
if (__stp_debugfs_module_dir) {
if (!_stp_lock_transport_dir()) {
errk("Couldn't lock transport directory.\n");
return;
}
debugfs_remove(__stp_debugfs_module_dir);
__stp_debugfs_module_dir = NULL;
_stp_debugfs_remove_root_dir();
_stp_unlock_transport_dir();
}
}
static struct dentry *_stp_lockfile = NULL;
static int _stp_lock_transport_dir(void)
{
int numtries = 0;
while ((_stp_lockfile = debugfs_create_dir("systemtap_lock", NULL)) == NULL) {
if (numtries++ >= 50)
return 0;
msleep(50);
}
return 1;
}
static void _stp_unlock_transport_dir(void)
{
if (_stp_lockfile) {
debugfs_remove(_stp_lockfile);
_stp_lockfile = NULL;
}
}
/* _stp_debugfs_get_root_dir() - creates root directory or returns
* a pointer to it if it already exists.
*
* The caller *must* lock the transport directory.
*/
static struct dentry *_stp_debugfs_get_root_dir(void)
{
struct file_system_type *fs;
struct super_block *sb;
const char *name = "systemtap";
if (__stp_debugfs_root_dir != NULL) {
return __stp_debugfs_root_dir;
}
fs = get_fs_type("debugfs");
if (!fs) {
errk("Couldn't find debugfs filesystem.\n");
return NULL;
}
__stp_debugfs_root_dir = debugfs_create_dir(name, NULL);
if (__stp_debugfs_root_dir == ERR_PTR(-EEXIST)) /* some kernels signal duplication this way */
__stp_debugfs_root_dir = NULL;
if (!__stp_debugfs_root_dir) {
/* Couldn't create it because it is already there, so
* find it. */
#ifdef STAPCONF_FS_SUPERS_HLIST
sb = hlist_entry(fs->fs_supers.first, struct super_block,
s_instances);
#else
sb = list_entry(fs->fs_supers.next, struct super_block,
s_instances);
#endif
_stp_lock_inode(sb->s_root->d_inode);
__stp_debugfs_root_dir = lookup_one_len(name, sb->s_root,
strlen(name));
_stp_unlock_inode(sb->s_root->d_inode);
if (!IS_ERR(__stp_debugfs_root_dir))
dput(__stp_debugfs_root_dir);
else {
__stp_debugfs_root_dir = NULL;
errk("Could not create or find transport directory.\n");
}
}
else if (IS_ERR(__stp_debugfs_root_dir)) {
__stp_debugfs_root_dir = NULL;
errk("Could not create root directory \"%s\", error %ld\n", name,
-PTR_ERR(__stp_debugfs_root_dir));
}
return __stp_debugfs_root_dir;
}
/* _stp_debugfs_remove_root_dir() - removes root directory (if empty)
*
* The caller *must* lock the transport directory.
*/
static void _stp_debugfs_remove_root_dir(void)
{
if (__stp_debugfs_root_dir) {
if (simple_empty(__stp_debugfs_root_dir)) {
debugfs_remove(__stp_debugfs_root_dir);
}
__stp_debugfs_root_dir = NULL;
}
}
// this is used by relay_v2 to place the traceN relayfs files.
static struct dentry *_stp_debugfs_get_module_dir(void)
{
return __stp_debugfs_module_dir;
}
// relay_v2 callbacks for creating per-cpu files
static int __stp_debugfs_relay_remove_buf_file_callback(struct dentry *dentry)
{
debugfs_remove(dentry);
return 0;
}
static struct dentry *
__stp_debugfs_relay_create_buf_file_callback(const char *filename,
struct dentry *parent,
#ifdef STAPCONF_RELAY_UMODE_T
umode_t mode,
#else
int mode,
#endif
struct rchan_buf *buf,
int *is_global)
{
struct dentry *file = debugfs_create_file(filename, mode, parent, buf,
&relay_file_operations_w_owner);
/*
* Here's what 'is_global' does (from linux/relay.h):
*
* Setting the is_global outparam to a non-zero value will
* cause relay_open() to create a single global buffer rather
* than the default set of per-cpu buffers.
*/
if (is_global)
*is_global = 0;
if (IS_ERR(file)) {
file = NULL;
}
else if (file) {
file->d_inode->i_uid = KUIDT_INIT(_stp_uid);
file->d_inode->i_gid = KGIDT_INIT(_stp_gid);
}
return file;
}