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#ifndef _TRANSPORT_RELAYFS_C_ /* -*- linux-c -*- */
#define _TRANSPORT_RELAYFS_C_
/*
* relayfs.c - stp relayfs-related transport functions
*
* Copyright (C) IBM Corporation, 2005
* Copyright (C) Redhat Inc, 2005
*
* This file is released under the GPL.
*/
/** @file relayfs.c
* @brief Systemtap relayfs-related transport functions
*/
/** @addtogroup transport Transport Functions
* @{
*/
#include "relayfs.h"
#if (RELAYFS_CHANNEL_VERSION >= 4) || defined (CONFIG_RELAY)
/**
* _stp_subbuf_start - subbuf_start() relayfs callback implementation
*/
static int _stp_subbuf_start(struct rchan_buf *buf,
void *subbuf,
void *prev_subbuf,
size_t prev_padding)
{
if (relay_buf_full(buf))
return 0;
if (prev_subbuf)
*((unsigned *)prev_subbuf) = prev_padding;
subbuf_start_reserve(buf, sizeof(unsigned int));
return 1;
}
#else
/**
* _stp_subbuf_start - subbuf_start() relayfs callback implementation
*/
static int _stp_subbuf_start(struct rchan_buf *buf,
void *subbuf,
unsigned prev_subbuf_idx,
void *prev_subbuf)
{
unsigned padding = buf->padding[prev_subbuf_idx];
if (prev_subbuf)
*((unsigned *)prev_subbuf) = padding;
return sizeof(padding); /* reserve space for padding */
}
/**
* _stp_buf_full - buf_full() relayfs callback implementation
*/
static void _stp_buf_full(struct rchan_buf *buf,
unsigned subbuf_idx,
void *subbuf)
{
unsigned padding = buf->padding[subbuf_idx];
*((unsigned *)subbuf) = padding;
}
#endif /* RELAYFS_CHANNEL_VERSION >= 4 || CONFIG_RELAY */
#if defined (CONFIG_RELAY)
static struct dentry *_stp_create_buf_file(const char *filename,
struct dentry *parent,
int mode,
struct rchan_buf *buf,
int *is_global)
{
return debugfs_create_file(filename, mode, parent, buf,
&relay_file_operations);
}
static int _stp_remove_buf_file(struct dentry *dentry)
{
debugfs_remove(dentry);
return 0;
}
#endif /* CONFIG_RELAY */
/* relayfs callback functions */
#if defined (CONFIG_RELAY)
static struct rchan_callbacks stp_rchan_callbacks =
{
.subbuf_start = _stp_subbuf_start,
.create_buf_file = _stp_create_buf_file,
.remove_buf_file = _stp_remove_buf_file,
};
#else
static struct rchan_callbacks stp_rchan_callbacks =
{
.subbuf_start = _stp_subbuf_start,
#if (RELAYFS_CHANNEL_VERSION < 4)
.buf_full = _stp_buf_full,
#endif /* RELAYFS_CHANNEL_VERSION < 4 */
};
#endif /* CONFIG_RELAY */
static struct dentry *_stp_create_relay_dir(const char *dirname, struct dentry *parent)
{
struct dentry *dir;
#if defined (CONFIG_RELAY)
dir = debugfs_create_dir(dirname, parent);
if (IS_ERR(dir)) {
printk("STP: Couldn't create directory %s - debugfs not configured in.\n", dirname);
dir = NULL;
}
#else
dir = relayfs_create_dir(dirname, parent);
#endif
return dir;
}
static void _stp_remove_relay_dir(struct dentry *dir)
{
if (dir == NULL)
return;
#if defined (CONFIG_RELAY)
debugfs_remove(dir);
#else
relayfs_remove_dir(dir);
#endif
}
static struct dentry *_stp_get_relay_root(void)
{
struct file_system_type *fs;
struct super_block *sb;
struct dentry *root;
char *dirname = "systemtap";
root = _stp_create_relay_dir(dirname, NULL);
if (root)
return root;
#if defined (CONFIG_RELAY)
fs = get_fs_type("debugfs");
#else
fs = get_fs_type("relayfs");
#endif
if (!fs)
return NULL;
sb = list_entry(fs->fs_supers.next, struct super_block, s_instances);
mutex_lock(&sb->s_root->d_inode->i_mutex);
root = lookup_one_len(dirname, sb->s_root, strlen(dirname));
mutex_unlock(&sb->s_root->d_inode->i_mutex);
if (!IS_ERR(root))
dput(root);
return root;
}
static void _stp_put_relay_root(struct dentry *root)
{
if (root)
_stp_remove_relay_dir(root);
}
static struct dentry *_relay_root;
/**
* _stp_relayfs_close - destroys relayfs channel
* @chan: the relayfs channel
* @dir: the directory containing the relayfs files
*/
void _stp_relayfs_close(struct rchan *chan, struct dentry *dir)
{
if (!chan)
return;
relay_close(chan);
_stp_remove_relay_dir(dir);
_stp_put_relay_root(_relay_root);
}
/**
* _stp_relayfs_open - create relayfs channel
* @n_subbufs: number of relayfs sub-buffers
* @subbuf_size: size of relayfs sub-buffers
* @pid: daemon pid
* @outdir: receives directory dentry
*
* Returns relay channel, NULL on failure
*
* Creates relayfs files as /systemtap/pid/cpuX in relayfs root
*/
struct rchan *_stp_relayfs_open(unsigned n_subbufs,
unsigned subbuf_size,
int pid,
struct dentry **outdir)
{
char dirname[16];
struct rchan *chan;
struct dentry* root, *dir;
sprintf(dirname, "%d", pid);
root = _stp_get_relay_root();
if (!root) {
printk("STP: couldn't get relay root dir.\n");
return NULL;
}
dir = _stp_create_relay_dir(dirname, root);
if (!dir) {
printk("STP: couldn't create relay dir %s.\n", dirname);
_stp_put_relay_root(root);
return NULL;
}
#if (RELAYFS_CHANNEL_VERSION >= 4)
chan = relay_open("cpu", dir, subbuf_size,
n_subbufs, &stp_rchan_callbacks);
#else
chan = relay_open("cpu", dir, subbuf_size,
n_subbufs, 0, &stp_rchan_callbacks);
#endif /* RELAYFS_CHANNEL_VERSION >= 4 */
if (!chan) {
printk("STP: couldn't create relay channel.\n");
_stp_remove_relay_dir(dir);
_stp_put_relay_root(root);
}
_relay_root = root;
*outdir = dir;
return chan;
}
#endif /* _TRANSPORT_RELAYFS_C_ */
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