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/* -*- linux-c -*-
* relayfs.c - relayfs transport functions
*
* Copyright (C) IBM Corporation, 2005, 2006
* Copyright (C) 2005-2008 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>
#include "utt.h"
static int _stp_relay_flushing = 0;
/**
* _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;
}
static struct rchan_callbacks stp_rchan_callbacks =
{
.subbuf_start = _stp_subbuf_start,
.buf_full = _stp_buf_full,
};
static void _stp_remove_relay_dir(struct dentry *dir)
{
if (dir)
relayfs_remove_dir(dir);
}
static void _stp_remove_relay_root(struct dentry *root)
{
if (root) {
if (!_stp_lock_transport_dir()) {
errk("Unable to lock transport directory.\n");
return;
}
_stp_remove_relay_dir(root);
_stp_unlock_transport_dir();
}
}
static struct utt_trace *utt_trace_setup(struct utt_trace_setup *utts)
{
struct utt_trace *utt;
int i;
utt = _stp_kzalloc(sizeof(*utt));
if (!utt)
return NULL;
utt->utt_tree_root = _stp_get_root_dir(utts->root);
if (!utt->utt_tree_root)
goto err;
utt->dir = relayfs_create_dir(utts->name, utt->utt_tree_root);
if (!utt->dir)
goto err;
dbug_trans(1, "relay_open %d %d\n", utts->buf_size, utts->buf_nr);
utt->rchan = relay_open("trace", utt->dir, utts->buf_size,
utts->buf_nr, 0, &stp_rchan_callbacks);
if (!utt->rchan)
goto err;
/* now set ownership */
for_each_online_cpu(i) {
utt->rchan->buf[i]->dentry->d_inode->i_uid = _stp_uid;
utt->rchan->buf[i]->dentry->d_inode->i_gid = _stp_gid;
}
utt->rchan->private_data = utt;
utt->trace_state = Utt_trace_setup;
utts->err = 0;
return utt;
err:
errk("couldn't create relay channel.\n");
if (utt->dir)
_stp_remove_relay_dir(utt->dir);
if (utt->utt_tree_root)
_stp_remove_relay_root(utt->utt_tree_root);
_stp_kfree(utt);
return NULL;
}
static void utt_set_overwrite(int overwrite)
{
if (_stp_utt)
_stp_utt->rchan->overwrite = overwrite;
}
static int utt_trace_startstop(struct utt_trace *utt, int start,
unsigned int *trace_seq)
{
int ret;
if (!utt)
return 0;
/*
* For starting a trace, we can transition from a setup or stopped
* trace. For stopping a trace, the state must be running
*/
ret = -EINVAL;
if (start) {
if (utt->trace_state == Utt_trace_setup ||
utt->trace_state == Utt_trace_stopped) {
if (trace_seq)
(*trace_seq)++;
smp_mb();
utt->trace_state = Utt_trace_running;
ret = 0;
}
} else {
if (utt->trace_state == Utt_trace_running) {
utt->trace_state = Utt_trace_stopped;
_stp_relay_flushing = 1;
relay_flush(utt->rchan);
ret = 0;
}
}
return ret;
}
static int utt_trace_remove(struct utt_trace *utt)
{
dbug_trans(1, "removing relayfs files. %d\n", utt->trace_state);
if (utt && (utt->trace_state == Utt_trace_setup || utt->trace_state == Utt_trace_stopped)) {
if (utt->rchan)
relay_close(utt->rchan);
if (utt->dir)
_stp_remove_relay_dir(utt->dir);
if (utt->utt_tree_root)
_stp_remove_relay_root(utt->utt_tree_root);
_stp_kfree(utt);
}
return 0;
}
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