Many struct file_operations in the kernel can be "const". Marking them const moves these to the .rodata section, which avoids false sharing with potential dirty data. In addition it'll catch accidental writes at compile time to these shared resources. Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
186 lines
4.3 KiB
C
186 lines
4.3 KiB
C
/*
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* tcpprobe - Observe the TCP flow with kprobes.
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*
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* The idea for this came from Werner Almesberger's umlsim
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* Copyright (C) 2004, Stephen Hemminger <shemminger@osdl.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include <linux/kernel.h>
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#include <linux/kprobes.h>
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#include <linux/socket.h>
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#include <linux/tcp.h>
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#include <linux/proc_fs.h>
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#include <linux/module.h>
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#include <linux/kfifo.h>
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#include <linux/vmalloc.h>
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#include <net/tcp.h>
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MODULE_AUTHOR("Stephen Hemminger <shemminger@linux-foundation.org>");
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MODULE_DESCRIPTION("TCP cwnd snooper");
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MODULE_LICENSE("GPL");
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static int port = 0;
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MODULE_PARM_DESC(port, "Port to match (0=all)");
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module_param(port, int, 0);
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static int bufsize = 64*1024;
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MODULE_PARM_DESC(bufsize, "Log buffer size (default 64k)");
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module_param(bufsize, int, 0);
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static const char procname[] = "tcpprobe";
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struct {
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struct kfifo *fifo;
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spinlock_t lock;
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wait_queue_head_t wait;
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struct timeval tstart;
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} tcpw;
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static void printl(const char *fmt, ...)
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{
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va_list args;
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int len;
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struct timeval now;
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char tbuf[256];
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va_start(args, fmt);
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do_gettimeofday(&now);
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now.tv_sec -= tcpw.tstart.tv_sec;
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now.tv_usec -= tcpw.tstart.tv_usec;
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if (now.tv_usec < 0) {
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--now.tv_sec;
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now.tv_usec += 1000000;
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}
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len = sprintf(tbuf, "%lu.%06lu ",
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(unsigned long) now.tv_sec,
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(unsigned long) now.tv_usec);
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len += vscnprintf(tbuf+len, sizeof(tbuf)-len, fmt, args);
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va_end(args);
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kfifo_put(tcpw.fifo, tbuf, len);
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wake_up(&tcpw.wait);
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}
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static int jtcp_sendmsg(struct kiocb *iocb, struct sock *sk,
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struct msghdr *msg, size_t size)
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{
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const struct tcp_sock *tp = tcp_sk(sk);
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const struct inet_sock *inet = inet_sk(sk);
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if (port == 0 || ntohs(inet->dport) == port ||
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ntohs(inet->sport) == port) {
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printl("%d.%d.%d.%d:%u %d.%d.%d.%d:%u %d %#x %#x %u %u %u\n",
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NIPQUAD(inet->saddr), ntohs(inet->sport),
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NIPQUAD(inet->daddr), ntohs(inet->dport),
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size, tp->snd_nxt, tp->snd_una,
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tp->snd_cwnd, tcp_current_ssthresh(sk),
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tp->snd_wnd);
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}
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jprobe_return();
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return 0;
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}
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static struct jprobe tcp_send_probe = {
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.kp = {
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.symbol_name = "tcp_sendmsg",
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},
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.entry = JPROBE_ENTRY(jtcp_sendmsg),
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};
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static int tcpprobe_open(struct inode * inode, struct file * file)
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{
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kfifo_reset(tcpw.fifo);
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do_gettimeofday(&tcpw.tstart);
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return 0;
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}
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static ssize_t tcpprobe_read(struct file *file, char __user *buf,
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size_t len, loff_t *ppos)
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{
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int error = 0, cnt = 0;
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unsigned char *tbuf;
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if (!buf || len < 0)
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return -EINVAL;
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if (len == 0)
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return 0;
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tbuf = vmalloc(len);
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if (!tbuf)
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return -ENOMEM;
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error = wait_event_interruptible(tcpw.wait,
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__kfifo_len(tcpw.fifo) != 0);
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if (error)
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goto out_free;
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cnt = kfifo_get(tcpw.fifo, tbuf, len);
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error = copy_to_user(buf, tbuf, cnt);
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out_free:
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vfree(tbuf);
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return error ? error : cnt;
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}
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static const struct file_operations tcpprobe_fops = {
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.owner = THIS_MODULE,
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.open = tcpprobe_open,
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.read = tcpprobe_read,
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};
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static __init int tcpprobe_init(void)
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{
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int ret = -ENOMEM;
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init_waitqueue_head(&tcpw.wait);
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spin_lock_init(&tcpw.lock);
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tcpw.fifo = kfifo_alloc(bufsize, GFP_KERNEL, &tcpw.lock);
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if (IS_ERR(tcpw.fifo))
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return PTR_ERR(tcpw.fifo);
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if (!proc_net_fops_create(procname, S_IRUSR, &tcpprobe_fops))
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goto err0;
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ret = register_jprobe(&tcp_send_probe);
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if (ret)
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goto err1;
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pr_info("TCP watch registered (port=%d)\n", port);
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return 0;
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err1:
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proc_net_remove(procname);
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err0:
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kfifo_free(tcpw.fifo);
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return ret;
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}
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module_init(tcpprobe_init);
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static __exit void tcpprobe_exit(void)
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{
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kfifo_free(tcpw.fifo);
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proc_net_remove(procname);
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unregister_jprobe(&tcp_send_probe);
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}
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module_exit(tcpprobe_exit);
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