That last fix was bad... the skb->users refcount change made it possible for
the skb to get double freed as skb->users was only incremented from one
immediately after calling dev_hard_xmit, this should address that I hope. I
now see thats what the old code was trying to avoid, but the old way fails
if the first packet attempted failed dev_hard_xmit. So it needs a fix
somehow. I am testing this by looping a script that starts pktgen with
count=10000 and clone_skb=100. Making sure it does not soft hang (requiring
a control c) or cause mem leaks.
Here is the updated patch.
--- linux-2.4.21/net/core/pktgen.c 2002-11-28 18:53:15.000000000 -0500
+++ linux-2.4-kjp/net/core/pktgen.c 2003-07-10 13:22:17.000000000 -0400
@@ -34,6 +34,7 @@
* * The new changes seem to have a performance impact of around 1%,
* as far as I can tell.
* --Ben Greear <greearb@xxxxxxxxxxxxxxx>
+ * Fix refcount off by one if first packet fails, potential null deref,
memleak 030710- KJP
*
* Renamed multiskb to clone_skb and cleaned up sending core for two
distinct
* skb modes. A clone_skb=0 mode for Ben "ranges" work and a clone_skb != 0
@@ -84,9 +85,9 @@
#define cycles() ((u32)get_cycles())
-#define VERSION "pktgen version 1.2"
+#define VERSION "pktgen version 1.2.1"
static char version[] __initdata =
- "pktgen.c: v1.2: Packet Generator for packet performance testing.\n";
+ "pktgen.c: v1.2.1: Packet Generator for packet performance testing.\n";
/* Used to help with determining the pkts on receive */
@@ -613,12 +614,11 @@
kfree_skb(skb);
skb = fill_packet(odev, info);
if (skb == NULL) {
- break;
+ goto out_reldev;
}
fp++;
fp_tmp = 0; /* reset counter */
}
- atomic_inc(&skb->users);
}
nr_frags = skb_shinfo(skb)->nr_frags;
@@ -626,7 +626,9 @@
spin_lock_bh(&odev->xmit_lock);
if (!netif_queue_stopped(odev)) {
+ atomic_inc(&skb->users);
if (odev->hard_start_xmit(skb, odev)) {
+ atomic_dec(&skb->users);
if (net_ratelimit()) {
printk(KERN_INFO "Hard xmit error\n");
}
@@ -634,9 +636,9 @@
last_ok = 0;
}
else {
- last_ok = 1;
- info->sofar++;
- info->seq_num++;
+ last_ok = 1;
+ info->sofar++;
+ info->seq_num++;
}
}
else {
@@ -731,6 +733,8 @@
(unsigned long long) info->errors
);
}
+
+ kfree_skb(skb);
out_reldev:
if (odev) {
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