Re: 2.6.9 RCU breakage in dev_queue_xmit

[Herbert Xu]

Jeff V. Merkey <jmerkey@xxxxxxxxx> wrote:
> 
> Running dual gigabit interfaces at 196 MB/S (megabytes/second) on 
> receive, 12 CLK interacket gap time, 1500 bytes payload
> at 65000 packets per second per gigabit interface, and retransmitting 
> received packets at 130 MB/S out of a third gigabit interface
> with skb, RCU locks in dev_queue_xmit breaks and enters the following state:

This patch might help.
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Email: Herbert Xu ~{PmV>HI~} <herbert@xxxxxxxxxxxxxxxxxxx>
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--
# This is a BitKeeper generated diff -Nru style patch.
#
# ChangeSet
#   2004/11/01 17:41:19-08:00 mingo@xxxxxxx 
#   [NET]: Fix unbalanced local_bh_enable() in dev_queue_xmit()
#   
#   Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
#   Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
# 
# net/core/dev.c
#   2004/11/01 17:40:59-08:00 mingo@xxxxxxx +5 -6
#   [NET]: Fix unbalanced local_bh_enable() in dev_queue_xmit()
#   
#   Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
#   Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
# 
diff -Nru a/net/core/dev.c b/net/core/dev.c
--- a/net/core/dev.c	2004-11-10 12:45:48 +11:00
+++ b/net/core/dev.c	2004-11-10 12:45:48 +11:00
@@ -1261,6 +1261,11 @@
 	struct Qdisc *q;
 	int rc = -ENOMEM;
 
+	/* Disable soft irqs for various locks below. Also 
+	 * stops preemption for RCU. 
+	 */
+	local_bh_disable(); 
+
 	if (skb_shinfo(skb)->frag_list &&
 	    !(dev->features & NETIF_F_FRAGLIST) &&
 	    __skb_linearize(skb, GFP_ATOMIC))
@@ -1284,12 +1289,6 @@
 	      skb->protocol != htons(ETH_P_IP))))
 	      	if (skb_checksum_help(skb, 0))
 	      		goto out_kfree_skb;
-
-
-	/* Disable soft irqs for various locks below. Also 
-	 * stops preemption for RCU. 
-	 */
-	local_bh_disable(); 
 
 	/* Updates of qdisc are serialized by queue_lock. 
 	 * The struct Qdisc which is pointed to by qdisc is now a 
-
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