Subject: Re: skge- "soft lockup on CPU#0" with mtu=9000 (2.6.20.1 + web100 patch)

From: Jay Vosburgh <[email-masked]>
Date: Thu, 08 Mar 2007 13:37:41 -0800

Chris Stromsoe <[email-masked]> wrote:

>Within 2 or 3 minutes after issuing
>
>ip link set bond1 mtu 9000
>
>I get one "NETDEV WATCHDOG: eth2: transmit timed out" to the console, and
>then this starts to repeat:
>
>BUG: soft lockup detected on CPU#0!

	I believe this is the same bug that is fixed by this change:

commit c4f283b1f275e5528c13c119e5cfc80cdba55d00
Author: Jay Vosburgh <[email-masked]>
Date:   Wed Feb 28 17:03:20 2007 -0800

    bonding: fix double dev_add_pack
    
        Bonding can erroneously register the same packet_type to receive
    ARPs (for use by ARP validation): once at device open time, and once via
    sysfs.  Since sysfs can change the validate setting (and thus register
    or unregister) at any time, a flag is needed to synchronize with device
    open in order to avoid double registrations, and the simplest place is
    within the packet_type structure itself.  Double unregister is not an
    issue.
    
        Bug reported by Ulrich Oelmann <[email-masked]>.
    
    Signed-off-by: Jay Vosburgh <[email-masked]>
    Signed-off-by: Jeff Garzik <[email-masked]>

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index ea73ebf..68afcb5 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -3423,6 +3423,9 @@ void bond_register_arp(struct bonding *b
 {
 	struct packet_type *pt = &bond->arp_mon_pt;
 
+	if (pt->type)
+		return;
+
 	pt->type = htons(ETH_P_ARP);
 	pt->dev = NULL; /*bond->dev;XXX*/
 	pt->func = bond_arp_rcv;
@@ -3431,7 +3434,10 @@ void bond_register_arp(struct bonding *b
 
 void bond_unregister_arp(struct bonding *bond)
 {
-	dev_remove_pack(&bond->arp_mon_pt);
+	struct packet_type *pt = &bond->arp_mon_pt;
+
+	dev_remove_pack(pt);
+	pt->type = 0;
 }
 
 /*---------------------------- Hashing Policies -----------------------------*/

	-J

---
	-Jay Vosburgh, IBM Linux Technology Center, [email-masked]