From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934108AbdKGAtV (ORCPT ); Mon, 6 Nov 2017 19:49:21 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:52803 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932664AbdKFXyM (ORCPT ); Mon, 6 Nov 2017 18:54:12 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "David S. Miller" , "Florian Fainelli" , "Petri Gynther" , "Jaedon Shin" Date: Mon, 06 Nov 2017 23:03:02 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 010/294] net: bcmgenet: fix off-by-one in incrementing read pointer In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.50-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Florian Fainelli commit cf377d886f7944a5ccdbd164b89949e13617b096 upstream. Commit b629be5c8399d7c423b92135eb43a86c924d1cbc ("net: bcmgenet: check harder for out of memory conditions") moved the increment of the local read pointer *before* reading from the hardware descriptor using dmadesc_get_length_status(), which creates an off-by-one situation. Fix this by moving again the read_ptr increment after we have read the hardware descriptor to get both the control block and the read pointer back in sync. Fixes: b629be5c8399 ("net: bcmgenet: check harder for out of memory conditions") Signed-off-by: Jaedon Shin Signed-off-by: Florian Fainelli Acked-by: Petri Gynther Signed-off-by: David S. Miller Signed-off-by: Ben Hutchings --- drivers/net/ethernet/broadcom/genet/bcmgenet.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) --- a/drivers/net/ethernet/broadcom/genet/bcmgenet.c +++ b/drivers/net/ethernet/broadcom/genet/bcmgenet.c @@ -1354,11 +1354,6 @@ static unsigned int bcmgenet_desc_rx(str cb = &priv->rx_cbs[priv->rx_read_ptr]; skb = cb->skb; - rxpktprocessed++; - - priv->rx_read_ptr++; - priv->rx_read_ptr &= (priv->num_rx_bds - 1); - /* We do not have a backing SKB, so we do not have a * corresponding DMA mapping for this incoming packet since * bcmgenet_rx_refill always either has both skb and mapping or @@ -1471,6 +1466,10 @@ refill: err = bcmgenet_rx_refill(priv, cb); if (err) netif_err(priv, rx_err, dev, "Rx refill failed\n"); + + rxpktprocessed++; + priv->rx_read_ptr++; + priv->rx_read_ptr &= (priv->num_rx_bds - 1); } return rxpktprocessed;