1 files changed, 124 insertions, 70 deletions

diff --git a/net/ipv4/tcp_probe.c b/net/ipv4/tcp_probe.c
index d9323dfff826..86624fabc4bf 100644
--- a/net/ipv4/tcp_probe.c
+++ b/net/ipv4/tcp_probe.c
@@ -6,8 +6,7 @@
  *
  * 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.
+ * the Free Software Foundation; either version 2 of the License.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ -25,23 +24,22 @@
 #include <linux/tcp.h>
 #include <linux/proc_fs.h>
 #include <linux/module.h>
-#include <linux/kfifo.h>
 #include <linux/ktime.h>
 #include <linux/time.h>
-#include <linux/vmalloc.h>
 
 #include <net/tcp.h>
 
 MODULE_AUTHOR("Stephen Hemminger <shemminger@linux-foundation.org>");
 MODULE_DESCRIPTION("TCP cwnd snooper");
 MODULE_LICENSE("GPL");
+MODULE_VERSION("1.1");
 
 static int port __read_mostly = 0;
 MODULE_PARM_DESC(port, "Port to match (0=all)");
 module_param(port, int, 0);
 
-static int bufsize __read_mostly = 64*1024;
-MODULE_PARM_DESC(bufsize, "Log buffer size (default 64k)");
+static int bufsize __read_mostly = 4096;
+MODULE_PARM_DESC(bufsize, "Log buffer size in packets (4096)");
 module_param(bufsize, int, 0);
 
 static int full __read_mostly;
@@ -50,39 +48,38 @@ module_param(full, int, 0);
 
 static const char procname[] = "tcpprobe";
 
-struct {
-	struct kfifo	*fifo;
+struct tcp_log {
+	ktime_t tstamp;
+	__be32	saddr, daddr;
+	__be16	sport, dport;
+	u16	length;
+	u32	snd_nxt;
+	u32	snd_una;
+	u32	snd_wnd;
+	u32	snd_cwnd;
+	u32	ssthresh;
+	u32	srtt;
+};
+
+static struct {
 	spinlock_t	lock;
 	wait_queue_head_t wait;
 	ktime_t		start;
 	u32		lastcwnd;
-} tcpw;
 
-/*
- * Print to log with timestamps.
- * FIXME: causes an extra copy
- */
-static void printl(const char *fmt, ...)
-	__attribute__ ((format (printf, 1, 2)));
+	unsigned long	head, tail;
+	struct tcp_log	*log;
+} tcp_probe;
+
 
-static void printl(const char *fmt, ...)
+static inline int tcp_probe_used(void)
 {
-	va_list args;
-	int len;
-	struct timespec tv;
-	char tbuf[256];
-
-	va_start(args, fmt);
-	/* want monotonic time since start of tcp_probe */
-	tv = ktime_to_timespec(ktime_sub(ktime_get(), tcpw.start));
-
-	len = sprintf(tbuf, "%lu.%09lu ",
-		      (unsigned long) tv.tv_sec, (unsigned long) tv.tv_nsec);
-	len += vscnprintf(tbuf+len, sizeof(tbuf)-len, fmt, args);
-	va_end(args);
-
-	kfifo_put(tcpw.fifo, tbuf, len);
-	wake_up(&tcpw.wait);
+	return (tcp_probe.head - tcp_probe.tail) % bufsize;
+}
+
+static inline int tcp_probe_avail(void)
+{
+	return bufsize - tcp_probe_used();
 }
 
 /*
@@ -97,63 +94,117 @@ static int jtcp_rcv_established(struct sock *sk, struct sk_buff *skb,
 
 	/* Only update if port matches */
 	if ((port == 0 || ntohs(inet->dport) == port || ntohs(inet->sport) == port)
-	    && (full || tp->snd_cwnd != tcpw.lastcwnd)) {
-		printl("%d.%d.%d.%d:%u %d.%d.%d.%d:%u %d %#x %#x %u %u %u %u\n",
-		       NIPQUAD(inet->saddr), ntohs(inet->sport),
-		       NIPQUAD(inet->daddr), ntohs(inet->dport),
-		       skb->len, tp->snd_nxt, tp->snd_una,
-		       tp->snd_cwnd, tcp_current_ssthresh(sk),
-		       tp->snd_wnd, tp->srtt >> 3);
-		tcpw.lastcwnd = tp->snd_cwnd;
+	    && (full || tp->snd_cwnd != tcp_probe.lastcwnd)) {
+
+		spin_lock(&tcp_probe.lock);
+		/* If log fills, just silently drop */
+		if (tcp_probe_avail() > 1) {
+			struct tcp_log *p = tcp_probe.log + tcp_probe.head;
+
+			p->tstamp = ktime_get();
+			p->saddr = inet->saddr;
+			p->sport = inet->sport;
+			p->daddr = inet->daddr;
+			p->dport = inet->dport;
+			p->length = skb->len;
+			p->snd_nxt = tp->snd_nxt;
+			p->snd_una = tp->snd_una;
+			p->snd_cwnd = tp->snd_cwnd;
+			p->snd_wnd = tp->snd_wnd;
+			p->srtt = tp->srtt >> 3;
+
+			tcp_probe.head = (tcp_probe.head + 1) % bufsize;
+		}
+		tcp_probe.lastcwnd = tp->snd_cwnd;
+		spin_unlock(&tcp_probe.lock);
+
+		wake_up(&tcp_probe.wait);
 	}
 
 	jprobe_return();
 	return 0;
 }
 
-static struct jprobe tcp_probe = {
+static struct jprobe tcp_jprobe = {
 	.kp = {
 		.symbol_name	= "tcp_rcv_established",
 	},
 	.entry	= JPROBE_ENTRY(jtcp_rcv_established),
 };
 
-
 static int tcpprobe_open(struct inode * inode, struct file * file)
 {
-	kfifo_reset(tcpw.fifo);
-	tcpw.start = ktime_get();
+	/* Reset (empty) log */
+	spin_lock_bh(&tcp_probe.lock);
+	tcp_probe.head = tcp_probe.tail = 0;
+	tcp_probe.start = ktime_get();
+	spin_unlock_bh(&tcp_probe.lock);
+
 	return 0;
 }
 
+static int tcpprobe_sprint(char *tbuf, int n)
+{
+	const struct tcp_log *p
+		= tcp_probe.log + tcp_probe.tail % bufsize;
+	struct timespec tv
+		= ktime_to_timespec(ktime_sub(p->tstamp, tcp_probe.start));
+
+	return snprintf(tbuf, n,
+			"%lu.%09lu %d.%d.%d.%d:%u %d.%d.%d.%d:%u"
+			" %d %#x %#x %u %u %u %u\n",
+			(unsigned long) tv.tv_sec,
+			(unsigned long) tv.tv_nsec,
+			NIPQUAD(p->saddr), ntohs(p->sport),
+			NIPQUAD(p->daddr), ntohs(p->dport),
+			p->length, p->snd_nxt, p->snd_una,
+			p->snd_cwnd, p->ssthresh, p->snd_wnd, p->srtt);
+}
+
 static ssize_t tcpprobe_read(struct file *file, char __user *buf,
 			     size_t len, loff_t *ppos)
 {
 	int error = 0, cnt = 0;
-	unsigned char *tbuf;
 
 	if (!buf || len < 0)
 		return -EINVAL;
 
-	if (len == 0)
-		return 0;
+	while (cnt < len) {
+		char tbuf[128];
+		int width;
+
+		/* Wait for data in buffer */
+		error = wait_event_interruptible(tcp_probe.wait,
+						 tcp_probe_used() > 0);
+		if (error)
+			break;
 
-	tbuf = vmalloc(len);
-	if (!tbuf)
-		return -ENOMEM;
+		spin_lock_bh(&tcp_probe.lock);
+		if (tcp_probe.head == tcp_probe.tail) {
+			/* multiple readers race? */
+			spin_unlock_bh(&tcp_probe.lock);
+			continue;
+		}
 
-	error = wait_event_interruptible(tcpw.wait,
-					 __kfifo_len(tcpw.fifo) != 0);
-	if (error)
-		goto out_free;
+		width = tcpprobe_sprint(tbuf, sizeof(tbuf));
 
-	cnt = kfifo_get(tcpw.fifo, tbuf, len);
-	error = copy_to_user(buf, tbuf, cnt);
+		if (width < len)
+			tcp_probe.tail = (tcp_probe.tail + 1) % bufsize;
 
-out_free:
-	vfree(tbuf);
+		spin_unlock_bh(&tcp_probe.lock);
+
+		/* if record greater than space available
+		   return partial buffer (so far) */
+		if (width >= len)
+			break;
+
+		error = copy_to_user(buf + cnt, tbuf, width);
+		if (error)
+			break;
+		cnt += width;
+	}
 
-	return error ? error : cnt;
+	return cnt == 0 ? error : cnt;
 }
 
 static const struct file_operations tcpprobe_fops = {
@@ -166,34 +217,37 @@ 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 (IS_ERR(tcpw.fifo))
-		return PTR_ERR(tcpw.fifo);
+	init_waitqueue_head(&tcp_probe.wait);
+	spin_lock_init(&tcp_probe.lock);
+
+	if (bufsize < 0)
+		return -EINVAL;
+
+	tcp_probe.log = kcalloc(sizeof(struct tcp_log), bufsize, GFP_KERNEL);
+	if (!tcp_probe.log)
+		goto err0;
 
 	if (!proc_net_fops_create(procname, S_IRUSR, &tcpprobe_fops))
 		goto err0;
 
-	ret = register_jprobe(&tcp_probe);
+	ret = register_jprobe(&tcp_jprobe);
 	if (ret)
 		goto err1;
 
-	pr_info("TCP watch registered (port=%d)\n", port);
+	pr_info("TCP probe registered (port=%d)\n", port);
 	return 0;
  err1:
 	proc_net_remove(procname);
  err0:
-	kfifo_free(tcpw.fifo);
+	kfree(tcp_probe.log);
 	return ret;
 }
 module_init(tcpprobe_init);
 
 static __exit void tcpprobe_exit(void)
 {
-	kfifo_free(tcpw.fifo);
 	proc_net_remove(procname);
-	unregister_jprobe(&tcp_probe);
-
+	unregister_jprobe(&tcp_jprobe);
+	kfree(tcp_probe.log);
 }
 module_exit(tcpprobe_exit);