be2net: Fix race in posting rx buffers.

There is a possibility of be_post_rx_frags() being called simultaneously from
both be_worker() (when rx_post_starved) and be_poll_rx() (when rxq->used is 0).
This can be avoided by posting rx buffers only when some completions have been
reaped.

Signed-off-by: Sathya Perla <sathya.perla@emulex.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/emulex/benet/be_main.c

@@ -1862,7 +1862,7 @@ static int be_poll_rx(struct napi_struct *napi, int budget)
 	}
 
 	/* Refill the queue */
-	if (atomic_read(&rxo->q.used) < RX_FRAGS_REFILL_WM)
+	if (work_done && atomic_read(&rxo->q.used) < RX_FRAGS_REFILL_WM)
 		be_post_rx_frags(rxo, GFP_ATOMIC);
 
 	/* All consumed */