sh_eth: Optimization for RX excess judgement

mitsu-kimura · davem330 · commit 319cd52013de · 2014-12-09T18:05:08.000-05:00
Both of 'boguscnt' and 'quota' have nearly meaning as the condition of
the reception loop.
In order to cut down redundant processing, this patch changes excess
judgement.

Signed-off-by: Mitsuhiro Kimura &lt;mitsuhiro.kimura.kc@renesas.com&gt;
Signed-off-by: Yoshihiro Kaneko &lt;ykaneko0929@gmail.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
diff --git a/drivers/net/ethernet/renesas/sh_eth.c b/drivers/net/ethernet/renesas/sh_eth.c
@@ -1395,10 +1395,13 @@ static int sh_eth_rx(struct net_device *ndev, u32 intr_status, int *quota)
 
 	int entry = mdp->cur_rx % mdp->num_rx_ring;
 	int boguscnt = (mdp->dirty_rx + mdp->num_rx_ring) - mdp->cur_rx;
+	int limit;
 	struct sk_buff *skb;
 	u16 pkt_len = 0;
 	u32 desc_status;
 
+	boguscnt = min(boguscnt, *quota);
+	limit = boguscnt;
 	rxdesc = &mdp->rx_ring[entry];
 	while (!(rxdesc->status & cpu_to_edmac(mdp, RD_RACT))) {
 		desc_status = edmac_to_cpu(mdp, rxdesc->status);
@@ -1407,11 +1410,6 @@ static int sh_eth_rx(struct net_device *ndev, u32 intr_status, int *quota)
 		if (--boguscnt < 0)
 			break;
 
-		if (*quota <= 0)
-			break;
-
-		(*quota)--;
-
 		if (!(desc_status & RDFEND))
 			ndev->stats.rx_length_errors++;
 
@@ -1502,6 +1500,8 @@ static int sh_eth_rx(struct net_device *ndev, u32 intr_status, int *quota)
 		sh_eth_write(ndev, EDRRR_R, EDRRR);
 	}
 
+	*quota -= limit - boguscnt - 1;
+
 	return *quota <= 0;
 }
 
