e1000e: fix flow control denial of service possibility
this patch avoids a denial of service from an evildoer sending a
continuous stream of flow control at our adapter that is plugged
into a non-flow control enabled switch.
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: Auke Kok <auke-jan.h.kok@intel.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/drivers/net/e1000e/lib.c b/drivers/net/e1000e/lib.c
index 0860b5f..341d74e 100644
--- a/drivers/net/e1000e/lib.c
+++ b/drivers/net/e1000e/lib.c
@@ -1104,34 +1104,13 @@
(mii_nway_lp_ability_reg & NWAY_LPAR_ASM_DIR)) {
mac->fc = e1000_fc_rx_pause;
hw_dbg(hw, "Flow Control = RX PAUSE frames only.\r\n");
- }
- /* Per the IEEE spec, at this point flow control should be
- * disabled. However, we want to consider that we could
- * be connected to a legacy switch that doesn't advertise
- * desired flow control, but can be forced on the link
- * partner. So if we advertised no flow control, that is
- * what we will resolve to. If we advertised some kind of
- * receive capability (Rx Pause Only or Full Flow Control)
- * and the link partner advertised none, we will configure
- * ourselves to enable Rx Flow Control only. We can do
- * this safely for two reasons: If the link partner really
- * didn't want flow control enabled, and we enable Rx, no
- * harm done since we won't be receiving any PAUSE frames
- * anyway. If the intent on the link partner was to have
- * flow control enabled, then by us enabling RX only, we
- * can at least receive pause frames and process them.
- * This is a good idea because in most cases, since we are
- * predominantly a server NIC, more times than not we will
- * be asked to delay transmission of packets than asking
- * our link partner to pause transmission of frames.
- */
- else if ((mac->original_fc == e1000_fc_none) ||
- (mac->original_fc == e1000_fc_tx_pause)) {
+ } else {
+ /*
+ * Per the IEEE spec, at this point flow control
+ * should be disabled.
+ */
mac->fc = e1000_fc_none;
hw_dbg(hw, "Flow Control = NONE.\r\n");
- } else {
- mac->fc = e1000_fc_rx_pause;
- hw_dbg(hw, "Flow Control = RX PAUSE frames only.\r\n");
}
/* Now we need to do one last check... If we auto-