cxgb4 : Disable recursive mailbox commands when enabling vi

Enabling a Virtual Interface can result in an interrupt during the processing
 of the VI Enable command and, in some paths, result in an attempt to issue
another command in the interrupt context, eventually crashing the system. Thus,
 we disable interrupts during the course of the VI Enable command and ensure
enable doesn't sleep.
Signed-off-by: Anish Bhatt <anish@chelsio.com>
Signed-off-by: Casey Leedom <leedom@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c

@@ -673,9 +673,12 @@ static int link_start(struct net_device *dev)
 	if (ret == 0)
 		ret = t4_link_start(pi->adapter, mb, pi->tx_chan,
 				    &pi->link_cfg);
-	if (ret == 0)
+	if (ret == 0) {
+		local_bh_disable();
 		ret = t4_enable_vi_params(pi->adapter, mb, pi->viid, true,
 					  true, CXGB4_DCB_ENABLED);
+		local_bh_enable();
+	}
 
 	return ret;
 }

drivers/net/ethernet/chelsio/cxgb4/t4_hw.c

@@ -3558,7 +3558,7 @@ int t4_enable_vi_params(struct adapter *adap, unsigned int mbox,
 	c.ien_to_len16 = htonl(FW_VI_ENABLE_CMD_IEN(rx_en) |
 			       FW_VI_ENABLE_CMD_EEN(tx_en) | FW_LEN16(c) |
 			       FW_VI_ENABLE_CMD_DCB_INFO(dcb_en));
-	return t4_wr_mbox(adap, mbox, &c, sizeof(c), NULL);
+	return t4_wr_mbox_ns(adap, mbox, &c, sizeof(c), NULL);
 }
 
 /**