From patchwork Wed Jul 24 08:00:45 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Barker X-Patchwork-Id: 13740661 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from aws-us-west-2-korg-lkml-1.web.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.lore.kernel.org (Postfix) with ESMTP id 648C7C49EA1 for ; Wed, 24 Jul 2024 08:01:18 +0000 (UTC) Received: from relmlie5.idc.renesas.com (relmlie5.idc.renesas.com [210.160.252.171]) by mx.groups.io with SMTP id smtpd.web10.5867.1721808052528588612 for ; Wed, 24 Jul 2024 01:01:12 -0700 Authentication-Results: mx.groups.io; dkim=none (message not signed); spf=pass (domain: bp.renesas.com, ip: 210.160.252.171, mailfrom: paul.barker.ct@bp.renesas.com) X-IronPort-AV: E=Sophos;i="6.09,232,1716217200"; d="scan'208";a="212533082" Received: from unknown (HELO relmlir6.idc.renesas.com) ([10.200.68.152]) by relmlie5.idc.renesas.com with ESMTP; 24 Jul 2024 17:01:11 +0900 Received: from ree-du1sdd5.ree.adwin.renesas.com (unknown [10.226.105.7]) by relmlir6.idc.renesas.com (Postfix) with ESMTP id F00FA41D15D7; Wed, 24 Jul 2024 17:01:09 +0900 (JST) From: Paul Barker To: cip-dev@lists.cip-project.org, Nobuhiro Iwamatsu , Pavel Machek Cc: Biju Das , Lad Prabhakar Subject: [PATCH 6.1.y-cip 10/11] net: ravb: Allow RX loop to move past DMA mapping errors Date: Wed, 24 Jul 2024 08:00:45 +0000 Message-Id: <20240724080046.1500825-11-paul.barker.ct@bp.renesas.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20240724080046.1500825-1-paul.barker.ct@bp.renesas.com> References: <20240724080046.1500825-1-paul.barker.ct@bp.renesas.com> MIME-Version: 1.0 List-Id: X-Webhook-Received: from li982-79.members.linode.com [45.33.32.79] by aws-us-west-2-korg-lkml-1.web.codeaurora.org with HTTPS for ; Wed, 24 Jul 2024 08:01:18 -0000 X-Groupsio-URL: https://lists.cip-project.org/g/cip-dev/message/16609 commit a892493a343494bd6bab9d098593932077ff3c43 upstream. The RX loops in ravb_rx_gbeth() and ravb_rx_rcar() skip to the next loop iteration if a zero-length descriptor is seen (indicating a DMA mapping error). However, the current RX descriptor index `priv->cur_rx[q]` was incremented at the end of the loop and so would not be incremented when we skip to the next loop iteration. This would cause the loop to keep seeing the same zero-length descriptor instead of moving on to the next descriptor. As the loop counter `i` still increments, the loop would eventually terminate so there is no risk of being stuck here forever - but we should still fix this to avoid wasting cycles. To fix this, the RX descriptor index is incremented at the top of the loop, in the for statement itself. The assignments of `entry` and `desc` are brought into the loop to avoid the need for duplication. Fixes: d8b48911fd24 ("ravb: fix ring memory allocation") Signed-off-by: Paul Barker Reviewed-by: Sergey Shtylyov Signed-off-by: Paolo Abeni Signed-off-by: Paul Barker --- drivers/net/ethernet/renesas/ravb_main.c | 25 ++++++++++++------------ 1 file changed, 13 insertions(+), 12 deletions(-) diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c index ff9f059e92f0..cc18cb9efb98 100644 --- a/drivers/net/ethernet/renesas/ravb_main.c +++ b/drivers/net/ethernet/renesas/ravb_main.c @@ -777,12 +777,15 @@ static bool ravb_rx_gbeth(struct net_device *ndev, int *quota, int q) int limit; int i; - entry = priv->cur_rx[q] % priv->num_rx_ring[q]; limit = priv->dirty_rx[q] + priv->num_rx_ring[q] - priv->cur_rx[q]; stats = &priv->stats[q]; - desc = &priv->rx_ring[q].desc[entry]; - for (i = 0; i < limit && rx_packets < *quota && desc->die_dt != DT_FEMPTY; i++) { + for (i = 0; i < limit; i++, priv->cur_rx[q]++) { + entry = priv->cur_rx[q] % priv->num_rx_ring[q]; + desc = &priv->rx_ring[q].desc[entry]; + if (rx_packets == *quota || desc->die_dt == DT_FEMPTY) + break; + /* Descriptor type must be checked before all other reads */ dma_rmb(); desc_status = desc->msc; @@ -850,9 +853,6 @@ static bool ravb_rx_gbeth(struct net_device *ndev, int *quota, int q) break; } } - - entry = (++priv->cur_rx[q]) % priv->num_rx_ring[q]; - desc = &priv->rx_ring[q].desc[entry]; } /* Refill the RX ring buffers. */ @@ -893,7 +893,6 @@ static bool ravb_rx_rcar(struct net_device *ndev, int *quota, int q) { struct ravb_private *priv = netdev_priv(ndev); const struct ravb_hw_info *info = priv->info; - int entry = priv->cur_rx[q] % priv->num_rx_ring[q]; struct net_device_stats *stats = &priv->stats[q]; struct ravb_ex_rx_desc *desc; unsigned int limit, i; @@ -903,10 +902,15 @@ static bool ravb_rx_rcar(struct net_device *ndev, int *quota, int q) int rx_packets = 0; u8 desc_status; u16 pkt_len; + int entry; limit = priv->dirty_rx[q] + priv->num_rx_ring[q] - priv->cur_rx[q]; - desc = &priv->rx_ring[q].ex_desc[entry]; - for (i = 0; i < limit && rx_packets < *quota && desc->die_dt != DT_FEMPTY; i++) { + for (i = 0; i < limit; i++, priv->cur_rx[q]++) { + entry = priv->cur_rx[q] % priv->num_rx_ring[q]; + desc = &priv->rx_ring[q].ex_desc[entry]; + if (rx_packets == *quota || desc->die_dt == DT_FEMPTY) + break; + /* Descriptor type must be checked before all other reads */ dma_rmb(); desc_status = desc->msc; @@ -960,9 +964,6 @@ static bool ravb_rx_rcar(struct net_device *ndev, int *quota, int q) rx_packets++; stats->rx_bytes += pkt_len; } - - entry = (++priv->cur_rx[q]) % priv->num_rx_ring[q]; - desc = &priv->rx_ring[q].ex_desc[entry]; } /* Refill the RX ring buffers. */