Commit a42e9d6c authored by Stephen Hemminger's avatar Stephen Hemminger Committed by David S. Miller
Browse files

[TCP]: TCP Probe congestion window tracing



This adds a new module for tracking TCP state variables non-intrusively
using kprobes.  It has a simple /proc interface that outputs one line
for each packet received. A sample usage is to collect congestion
window and ssthresh over time graphs.
Signed-off-by: default avatarStephen Hemminger <shemminger@osdl.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 72dc5b92
......@@ -215,6 +215,21 @@ config NET_PKTGEN
To compile this code as a module, choose M here: the
module will be called pktgen.
config NET_TCPPROBE
tristate "TCP connection probing"
depends on INET && EXPERIMENTAL && PROC_FS && KPROBES
---help---
This module allows for capturing the changes to TCP connection
state in response to incoming patckets. It is used for debugging
TCP congestion avoidance modules. If you don't understand
what was just said, you don't need it: say N.
Documentation on how to use the packet generator can be found
at http://linux-net.osdl.org/index.php/TcpProbe
To compile this code as a module, choose M here: the
module will be called tcp_probe.
endmenu
endmenu
......
......@@ -36,6 +36,7 @@ obj-$(CONFIG_IP_VS) += ipvs/
obj-$(CONFIG_INET_DIAG) += inet_diag.o
obj-$(CONFIG_IP_ROUTE_MULTIPATH_CACHED) += multipath.o
obj-$(CONFIG_INET_TCP_DIAG) += tcp_diag.o
obj-$(CONFIG_NET_TCPPROBE) += tcp_probe.o
obj-$(CONFIG_TCP_CONG_BIC) += tcp_bic.o
obj-$(CONFIG_TCP_CONG_CUBIC) += tcp_cubic.o
obj-$(CONFIG_TCP_CONG_WESTWOOD) += tcp_westwood.o
......
/*
* tcpprobe - Observe the TCP flow with kprobes.
*
* The idea for this came from Werner Almesberger's umlsim
* Copyright (C) 2004, Stephen Hemminger <shemminger@osdl.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <linux/kernel.h>
#include <linux/kprobes.h>
#include <linux/socket.h>
#include <linux/tcp.h>
#include <linux/proc_fs.h>
#include <linux/module.h>
#include <linux/kfifo.h>
#include <linux/vmalloc.h>
#include <net/tcp.h>
MODULE_AUTHOR("Stephen Hemminger <shemminger@osdl.org>");
MODULE_DESCRIPTION("TCP cwnd snooper");
MODULE_LICENSE("GPL");
static int port = 0;
MODULE_PARM_DESC(port, "Port to match (0=all)");
module_param(port, int, 0);
static int bufsize = 64*1024;
MODULE_PARM_DESC(bufsize, "Log buffer size (default 64k)");
module_param(bufsize, int, 0);
static const char procname[] = "tcpprobe";
struct {
struct kfifo *fifo;
spinlock_t lock;
wait_queue_head_t wait;
struct timeval tstart;
} tcpw;
static void printl(const char *fmt, ...)
{
va_list args;
int len;
struct timeval now;
char tbuf[256];
va_start(args, fmt);
do_gettimeofday(&now);
now.tv_sec -= tcpw.tstart.tv_sec;
now.tv_usec -= tcpw.tstart.tv_usec;
if (now.tv_usec < 0) {
--now.tv_sec;
now.tv_usec += 1000000;
}
len = sprintf(tbuf, "%lu.%06lu ", now.tv_sec, now.tv_usec);
len += vscnprintf(tbuf+len, sizeof(tbuf)-len, fmt, args);
va_end(args);
kfifo_put(tcpw.fifo, tbuf, len);
wake_up(&tcpw.wait);
}
static int jtcp_sendmsg(struct kiocb *iocb, struct sock *sk,
struct msghdr *msg, size_t size)
{
const struct tcp_sock *tp = tcp_sk(sk);
const struct inet_sock *inet = inet_sk(sk);
if (port == 0 || ntohs(inet->dport) == port ||
ntohs(inet->sport) == port) {
printl("%d.%d.%d.%d:%u %d.%d.%d.%d:%u %d %#x %#x %u %u %u\n",
NIPQUAD(inet->saddr), ntohs(inet->sport),
NIPQUAD(inet->daddr), ntohs(inet->dport),
size, tp->snd_nxt, tp->snd_una,
tp->snd_cwnd, tcp_current_ssthresh(sk),
tp->snd_wnd);
}
jprobe_return();
return 0;
}
static struct jprobe tcp_send_probe = {
.kp = { .addr = (kprobe_opcode_t *) &tcp_sendmsg, },
.entry = (kprobe_opcode_t *) &jtcp_sendmsg,
};
static int tcpprobe_open(struct inode * inode, struct file * file)
{
kfifo_reset(tcpw.fifo);
do_gettimeofday(&tcpw.tstart);
return 0;
}
static ssize_t tcpprobe_read(struct file *file, char __user *buf,
size_t len, loff_t *ppos)
{
int error = 0, cnt;
unsigned char *tbuf;
if (!buf || len < 0)
return -EINVAL;
if (len == 0)
return 0;
tbuf = vmalloc(len);
if (!tbuf)
return -ENOMEM;
error = wait_event_interruptible(tcpw.wait,
__kfifo_len(tcpw.fifo) != 0);
if (error)
return error;
cnt = kfifo_get(tcpw.fifo, tbuf, len);
error = copy_to_user(buf, tbuf, cnt);
vfree(tbuf);
return error ? error : cnt;
}
static struct file_operations tcpprobe_fops = {
.owner = THIS_MODULE,
.open = tcpprobe_open,
.read = tcpprobe_read,
};
static __init int tcpprobe_init(void)
{
int ret = -ENOMEM;
init_waitqueue_head(&tcpw.wait);
spin_lock_init(&tcpw.lock);
tcpw.fifo = kfifo_alloc(bufsize, GFP_KERNEL, &tcpw.lock);
if (!proc_net_fops_create(procname, S_IRUSR, &tcpprobe_fops))
goto err0;
ret = register_jprobe(&tcp_send_probe);
if (ret)
goto err1;
pr_info("TCP watch registered (port=%d)\n", port);
return 0;
err1:
proc_net_remove(procname);
err0:
kfifo_free(tcpw.fifo);
return ret;
}
module_init(tcpprobe_init);
static __exit void tcpprobe_exit(void)
{
kfifo_free(tcpw.fifo);
proc_net_remove(procname);
unregister_jprobe(&tcp_send_probe);
}
module_exit(tcpprobe_exit);
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