netdev - [PATCH 1/2] net: ethernet: altera: TSE: Remove unneeded dma sync for tx buffers

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:   Wed, 30 Nov 2016 23:48:31 +0100
From:   Lino Sanfilippo <LinoSanfilippo@....de>
To:     vbridger@...nsource.altera.com
Cc:     nios2-dev@...ts.rocketboards.org, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org, Lino Sanfilippo <LinoSanfilippo@....de>
Subject: [PATCH 1/2] net: ethernet: altera: TSE: Remove unneeded dma sync for tx buffers

An explicit dma sync for device directly after mapping as well as an
explicit dma sync for cpu directly before unmapping is unnecessary and
costly on the hotpath. So remove these calls.

Signed-off-by: Lino Sanfilippo <LinoSanfilippo@....de>
---
 drivers/net/ethernet/altera/altera_tse_main.c | 10 ----------
 1 file changed, 10 deletions(-)

 Please note that this is only compile tested since I do not have the
 concerning hardware.

diff --git a/drivers/net/ethernet/altera/altera_tse_main.c b/drivers/net/ethernet/altera/altera_tse_main.c
index bda31f3..16c4163 100644
--- a/drivers/net/ethernet/altera/altera_tse_main.c
+++ b/drivers/net/ethernet/altera/altera_tse_main.c
@@ -400,12 +400,6 @@ static int tse_rx(struct altera_tse_private *priv, int limit)
 
 		skb_put(skb, pktlength);
 
-		/* make cache consistent with receive packet buffer */
-		dma_sync_single_for_cpu(priv->device,
-					priv->rx_ring[entry].dma_addr,
-					priv->rx_ring[entry].len,
-					DMA_FROM_DEVICE);
-
 		dma_unmap_single(priv->device, priv->rx_ring[entry].dma_addr,
 				 priv->rx_ring[entry].len, DMA_FROM_DEVICE);
 
@@ -592,10 +586,6 @@ static int tse_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	buffer->dma_addr = dma_addr;
 	buffer->len = nopaged_len;
 
-	/* Push data out of the cache hierarchy into main memory */
-	dma_sync_single_for_device(priv->device, buffer->dma_addr,
-				   buffer->len, DMA_TO_DEVICE);
-
 	priv->dmaops->tx_buffer(priv, buffer);
 
 	skb_tx_timestamp(skb);
-- 
2.7.4