[PATCH] [UPDATED] pktgen fixes ....
From: Kambo Lohan <hidden>
Date: 2003-07-10 17:40:04
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.
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--- 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@candelatech.com> + * 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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