[PATCH net] ppp: annotate concurrent dev->stats accesses

[PATCH net] ppp: annotate concurrent dev->stats accesses

[Eric Dumazet]

dev->stats fields can be updated concurrently from multiple CPUs
without synchronization.

Use DEV_STATS_INC() for stats increments and DEV_STATS_READ()
when reading dev->stats in ppp_get_stats64() and ppp_get_stats()
to avoid data races.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 drivers/net/ppp/ppp_generic.c | 32 ++++++++++++++++----------------
 1 file changed, 16 insertions(+), 16 deletions(-)

diff --git a/drivers/net/ppp/ppp_generic.c b/drivers/net/ppp/ppp_generic.c
index 717c1d3aa95380da64eb5ae6fc1da6e4dfaa9d87..ef54e0a0462a175bb989db8dda895e9ae755965f 100644
--- a/drivers/net/ppp/ppp_generic.c
+++ b/drivers/net/ppp/ppp_generic.c
@@ -1482,7 +1482,7 @@ ppp_start_xmit(struct sk_buff *skb, struct net_device *dev)
 
  outf:
 	kfree_skb(skb);
-	++dev->stats.tx_dropped;
+	DEV_STATS_INC(dev, tx_dropped);
 	return NETDEV_TX_OK;
 }
 
@@ -1532,11 +1532,11 @@ ppp_net_siocdevprivate(struct net_device *dev, struct ifreq *ifr,
 static void
 ppp_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats64)
 {
-	stats64->rx_errors        = dev->stats.rx_errors;
-	stats64->tx_errors        = dev->stats.tx_errors;
-	stats64->rx_dropped       = dev->stats.rx_dropped;
-	stats64->tx_dropped       = dev->stats.tx_dropped;
-	stats64->rx_length_errors = dev->stats.rx_length_errors;
+	stats64->rx_errors        = DEV_STATS_READ(dev, rx_errors);
+	stats64->tx_errors        = DEV_STATS_READ(dev, tx_errors);
+	stats64->rx_dropped       = DEV_STATS_READ(dev, rx_dropped);
+	stats64->tx_dropped       = DEV_STATS_READ(dev, tx_dropped);
+	stats64->rx_length_errors = DEV_STATS_READ(dev, rx_length_errors);
 	dev_fetch_sw_netstats(stats64, dev->tstats);
 }
 
@@ -1889,7 +1889,7 @@ ppp_prepare_tx_skb(struct ppp *ppp, struct sk_buff **pskb)
 
  drop:
 	kfree_skb(skb);
-	++ppp->dev->stats.tx_errors;
+	DEV_STATS_INC(ppp->dev, tx_errors);
 	return 1;
 }
 
@@ -2156,7 +2156,7 @@ static int ppp_mp_explode(struct ppp *ppp, struct sk_buff *skb)
  err_linearize:
 	if (ppp->debug & 1)
 		netdev_err(ppp->dev, "PPP: no memory (fragment)\n");
-	++ppp->dev->stats.tx_errors;
+	DEV_STATS_INC(ppp->dev, tx_errors);
 	++ppp->nxseq;
 	return 1;	/* abandon the frame */
 }
@@ -2329,7 +2329,7 @@ ppp_input(struct ppp_channel *chan, struct sk_buff *skb)
 	if (!ppp_decompress_proto(skb)) {
 		kfree_skb(skb);
 		if (ppp) {
-			++ppp->dev->stats.rx_length_errors;
+			DEV_STATS_INC(ppp->dev, rx_length_errors);
 			ppp_receive_error(ppp);
 		}
 		goto done;
@@ -2391,7 +2391,7 @@ ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
 static void
 ppp_receive_error(struct ppp *ppp)
 {
-	++ppp->dev->stats.rx_errors;
+	DEV_STATS_INC(ppp->dev, rx_errors);
 	if (ppp->vj)
 		slhc_toss(ppp->vj);
 }
@@ -2658,7 +2658,7 @@ ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
 	 */
 	if (seq_before(seq, ppp->nextseq)) {
 		kfree_skb(skb);
-		++ppp->dev->stats.rx_dropped;
+		DEV_STATS_INC(ppp->dev, rx_dropped);
 		ppp_receive_error(ppp);
 		return;
 	}
@@ -2694,7 +2694,7 @@ ppp_receive_mp_frame(struct ppp *ppp, struct sk_buff *skb, struct channel *pch)
 		if (pskb_may_pull(skb, 2))
 			ppp_receive_nonmp_frame(ppp, skb);
 		else {
-			++ppp->dev->stats.rx_length_errors;
+			DEV_STATS_INC(ppp->dev, rx_length_errors);
 			kfree_skb(skb);
 			ppp_receive_error(ppp);
 		}
@@ -2800,7 +2800,7 @@ ppp_mp_reconstruct(struct ppp *ppp)
 		if (lost == 0 && (PPP_MP_CB(p)->BEbits & E) &&
 		    (PPP_MP_CB(head)->BEbits & B)) {
 			if (len > ppp->mrru + 2) {
-				++ppp->dev->stats.rx_length_errors;
+				DEV_STATS_INC(ppp->dev, rx_length_errors);
 				netdev_printk(KERN_DEBUG, ppp->dev,
 					      "PPP: reconstructed packet"
 					      " is too long (%d)\n", len);
@@ -2855,7 +2855,7 @@ ppp_mp_reconstruct(struct ppp *ppp)
 					      "  missed pkts %u..%u\n",
 					      ppp->nextseq,
 					      PPP_MP_CB(head)->sequence-1);
-			++ppp->dev->stats.rx_dropped;
+			DEV_STATS_INC(ppp->dev, rx_dropped);
 			ppp_receive_error(ppp);
 		}
 
@@ -3322,8 +3322,8 @@ ppp_get_stats(struct ppp *ppp, struct ppp_stats *st)
 		st->p.ppp_opackets += tx_packets;
 		st->p.ppp_obytes += tx_bytes;
 	}
-	st->p.ppp_ierrors = ppp->dev->stats.rx_errors;
-	st->p.ppp_oerrors = ppp->dev->stats.tx_errors;
+	st->p.ppp_ierrors = DEV_STATS_READ(ppp->dev, rx_errors);
+	st->p.ppp_oerrors = DEV_STATS_READ(ppp->dev, tx_errors);
 	if (!vj)
 		return;
 	st->vj.vjs_packets = vj->sls_o_compressed + vj->sls_o_uncompressed;
-- 
2.55.0.141.g00534a21ce-goog