ixgb: fix race on rx_buffer_len in mtu change
some random coverage testing found that when changing mtu
under heavy traffic load, NAPI would use the rx_buffer_len variable
after it had been changed by change_mtu.
Similar to e1000 bugs found long ago.
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
diff --git a/drivers/net/ixgb/ixgb_main.c b/drivers/net/ixgb/ixgb_main.c
index 4bf6bbc..c3234c4 100644
--- a/drivers/net/ixgb/ixgb_main.c
+++ b/drivers/net/ixgb/ixgb_main.c
@@ -1573,14 +1573,18 @@
return -EINVAL;
}
+ if (old_max_frame == max_frame)
+ return 0;
+
+ if (netif_running(netdev))
+ ixgb_down(adapter, true);
+
adapter->rx_buffer_len = max_frame + 8; /* + 8 for errata */
netdev->mtu = new_mtu;
- if ((old_max_frame != max_frame) && netif_running(netdev)) {
- ixgb_down(adapter, true);
+ if (netif_running(netdev))
ixgb_up(adapter);
- }
return 0;
}