From: Eric Dumazet <edumazet@google.com>
Date: Tue, 2 Dec 2014 12:30:59 +0000 (-0800)
Subject: net: mvneta: fix race condition in mvneta_tx()
X-Git-Tag: v3.19-rc1~118^2~10^2~16
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=5f478b41033606d325e420df693162e2524c2b94;p=karo-tx-linux.git

net: mvneta: fix race condition in mvneta_tx()

mvneta_tx() dereferences skb to get skb->len too late,
as hardware might have completed the transmit and TX completion
could have freed the skb from another cpu.

Fixes: 71f6d1b31fb1 ("net: mvneta: replace Tx timer with a real interrupt")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
index bb4afe6ccc85..67a84cfaefa1 100644
--- a/drivers/net/ethernet/marvell/mvneta.c
+++ b/drivers/net/ethernet/marvell/mvneta.c
@@ -1721,6 +1721,7 @@ static int mvneta_tx(struct sk_buff *skb, struct net_device *dev)
 	u16 txq_id = skb_get_queue_mapping(skb);
 	struct mvneta_tx_queue *txq = &pp->txqs[txq_id];
 	struct mvneta_tx_desc *tx_desc;
+	int len = skb->len;
 	int frags = 0;
 	u32 tx_cmd;
 
@@ -1788,7 +1789,7 @@ out:
 
 		u64_stats_update_begin(&stats->syncp);
 		stats->tx_packets++;
-		stats->tx_bytes  += skb->len;
+		stats->tx_bytes  += len;
 		u64_stats_update_end(&stats->syncp);
 	} else {
 		dev->stats.tx_dropped++;