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 <ulrich.oelmann@web.de>.

Signed-off-by: Jay Vosburgh <fubar@us.ibm.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 7 insertions, 1 deletions

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index ea73ebff4387..68afcb5d7257 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 *bond)
 {
         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 *bond)
 
 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 -----------------------------*/