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);