Current File : //usr/share/systemtap/runtime/transport/relayfs.c
/* -*- linux-c -*-
* relayfs.c - relayfs transport functions
*
* Copyright (C) IBM Corporation, 2005, 2006
* Copyright (C) 2005-2009 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.
*/
/* This file is only for older kernels that have no debugfs. */
/* relayfs is required! */
#if !defined (CONFIG_RELAYFS_FS) && !defined (CONFIG_RELAYFS_FS_MODULE)
#error "RelayFS does not appear to be in this kernel!"
#endif
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/percpu.h>
#include <linux/init.h>
#include <linux/relayfs_fs.h>
#include <linux/namei.h>
/* Note: if struct _stp_relay_data_type changes, staplog.c might need
* to be changed. */
struct _stp_relay_data_type {
struct rchan *rchan;
enum _stp_transport_state transport_state;
int flushing;
};
struct _stp_relay_data_type _stp_relay_data;
/* We need to include procfs.c here so that it can see the
* _stp_relay_data_type definition. */
#include "procfs.c"
/**
* __stp_relay_subbuf_start_callback - subbuf_start() relayfs
* callback implementation
*/
static int
__stp_relay_subbuf_start_callback(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_relay_buf_full_callback - buf_full() relayfs callback
* implementation
*/
static void __stp_relay_buf_full_callback(struct rchan_buf *buf,
unsigned subbuf_idx,
void *subbuf)
{
unsigned padding = buf->padding[subbuf_idx];
*((unsigned *)subbuf) = padding;
}
static struct rchan_callbacks stp_rchan_callbacks =
{
.subbuf_start = __stp_relay_subbuf_start_callback,
.buf_full = __stp_relay_buf_full_callback,
};
static void _stp_transport_data_fs_start(void)
{
if (_stp_relay_data.transport_state == STP_TRANSPORT_INITIALIZED)
_stp_relay_data.transport_state = STP_TRANSPORT_RUNNING;
}
static void _stp_transport_data_fs_stop(void)
{
if (_stp_relay_data.transport_state == STP_TRANSPORT_RUNNING) {
_stp_relay_data.transport_state = STP_TRANSPORT_STOPPED;
_stp_relay_data.flushing = 1;
if (_stp_relay_data.rchan)
relay_flush(_stp_relay_data.rchan);
}
}
static void _stp_transport_data_fs_close(void)
{
_stp_transport_data_fs_stop();
if (_stp_relay_data.rchan) {
relay_close(_stp_relay_data.rchan);
_stp_relay_data.rchan = NULL;
}
}
static int _stp_transport_data_fs_init(void)
{
int rc = 0;
int i;
dbug_trans(1, "relay_open %d %d\n", _stp_subbuf_size, _stp_nsubbufs);
_stp_relay_data.transport_state = STP_TRANSPORT_STOPPED;
_stp_relay_data.flushing = 0;
/* Create "trace" file. */
_stp_relay_data.rchan = relay_open("trace", _stp_get_module_dir(),
_stp_subbuf_size, _stp_nsubbufs,
0, &stp_rchan_callbacks);
if (!_stp_relay_data.rchan) {
rc = -ENOENT;
goto err;
}
{
u64 relay_mem;
relay_mem = _stp_subbuf_size * _stp_nsubbufs;
#ifdef STP_BULKMODE
relay_mem *= num_online_cpus();
#endif
_stp_allocated_net_memory += relay_mem;
_stp_allocated_memory += relay_mem;
}
/* now set ownership */
for_each_online_cpu(i) {
_stp_relay_data.rchan->buf[i]->dentry->d_inode->i_uid
= _stp_uid;
_stp_relay_data.rchan->buf[i]->dentry->d_inode->i_gid
= _stp_gid;
}
/* We're initialized. */
_stp_relay_data.transport_state = STP_TRANSPORT_INITIALIZED;
return rc;
err:
errk("couldn't create relay channel.\n");
_stp_transport_data_fs_close();
return rc;
}
static enum _stp_transport_state _stp_transport_get_state(void)
{
return _stp_relay_data.transport_state;
}
static void _stp_transport_data_fs_overwrite(int overwrite)
{
_stp_relay_data.rchan->overwrite = overwrite;
}
/**
* _stp_data_write_reserve - try to reserve size_request bytes
* @size_request: number of bytes to attempt to reserve
* @entry: entry is returned here
*
* Returns number of bytes reserved, 0 if full. On return, entry
* will point to allocated opaque pointer. Use
* _stp_data_entry_data() to get pointer to copy data into.
*
* (For this code's purposes, entry is filled in with the actual
* data pointer, but the caller doesn't know that.)
*/
static size_t
_stp_data_write_reserve(size_t size_request, void **entry)
{
if (entry == NULL)
return -EINVAL;
*entry = relay_reserve(_stp_relay_data.rchan, size_request);
if (*entry == NULL)
return 0;
return size_request;
}
static unsigned char *_stp_data_entry_data(void *entry)
{
/* Nothing to do here. */
return entry;
}
static int _stp_data_write_commit(void *entry)
{
/* Nothing to do here. */
return 0;
}
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