RE: [PATCH 06/14] net: axienet: Check for DMA mapping errors
From: Radhey Shyam Pandey <hidden>
Date: 2020-01-13 05:54:48
Also in:
linux-arm-kernel, lkml
quoted hunk ↗ jump to hunk
-----Original Message----- From: Andre Przywara <andre.przywara@arm.com> Sent: Friday, January 10, 2020 5:24 PM To: David S . Miller <davem@davemloft.net>; Radhey Shyam Pandey [off-list ref] Cc: Michal Simek <redacted>; Robert Hancock [off-list ref]; netdev@vger.kernel.org; linux-arm- kernel@lists.infradead.org; linux-kernel@vger.kernel.org Subject: [PATCH 06/14] net: axienet: Check for DMA mapping errors Especially with the default 32-bit DMA mask, DMA buffers are a limited resource, so their allocation can fail. So as the DMA API documentation requires, add error checking code after dma_map_single() calls to catch the case where we run out of "low" memory. Signed-off-by: Andre Przywara <andre.przywara@arm.com> --- .../net/ethernet/xilinx/xilinx_axienet_main.c | 22 ++++++++++++++++++- 1 file changed, 21 insertions(+), 1 deletion(-)diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_main.cb/drivers/net/ethernet/xilinx/xilinx_axienet_main.c index 82abe2b0f16a..8d2b67cbecf9 100644--- a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c +++ b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c@@ -248,6 +248,11 @@ static int axienet_dma_bd_init(struct net_device*ndev) skb->data, lp->max_frm_size, DMA_FROM_DEVICE); + if (dma_mapping_error(ndev->dev.parent, lp->rx_bd_v[i].phys))
Prefer using unlikely compiler hint for dma_mapping_error. Also, we need to add error print to report this condition to the user, in case it isn't there in dma_mapping_error implementation.
{
+ dev_kfree_skb(skb);free of skb is already handled in _release. We can reuse that?
quoted hunk ↗ jump to hunk
+ goto out; + } + lp->rx_bd_v[i].cntrl = lp->max_frm_size; }@@ -668,6 +673,7 @@ axienet_start_xmit(struct sk_buff *skb, structnet_device *ndev) dma_addr_t tail_p; struct axienet_local *lp = netdev_priv(ndev); struct axidma_bd *cur_p; + u32 orig_tail_ptr = lp->tx_bd_tail; num_frag = skb_shinfo(skb)->nr_frags; cur_p = &lp->tx_bd_v[lp->tx_bd_tail];@@ -703,9 +709,11 @@ axienet_start_xmit(struct sk_buff *skb, structnet_device *ndev) cur_p->app0 |= 2; /* Tx Full Checksum Offload Enabled */ } - cur_p->cntrl = skb_headlen(skb) | XAXIDMA_BD_CTRL_TXSOF_MASK; cur_p->phys = dma_map_single(ndev->dev.parent, skb->data, skb_headlen(skb), DMA_TO_DEVICE); + if (dma_mapping_error(ndev->dev.parent, cur_p->phys)) + return NETDEV_TX_BUSY;
This is not ideally tx busy and related to available mem mapping in the system. I just looked at other eth drivers and it seems they return TX_OK with drop count stats incremented.
quoted hunk ↗ jump to hunk
+ cur_p->cntrl = skb_headlen(skb) | XAXIDMA_BD_CTRL_TXSOF_MASK; for (ii = 0; ii < num_frag; ii++) { if (++lp->tx_bd_tail >= lp->tx_bd_num) @@ -716,6 +724,13 @@ axienet_start_xmit(struct sk_buff *skb, struct net_device *ndev) skb_frag_address(frag), skb_frag_size(frag), DMA_TO_DEVICE); + if (dma_mapping_error(ndev->dev.parent, cur_p->phys)) { + axienet_free_tx_chain(ndev, orig_tail_ptr, ii + 1, + NULL); + lp->tx_bd_tail = orig_tail_ptr; + + return NETDEV_TX_BUSY; + } cur_p->cntrl = skb_frag_size(frag); }@@ -796,6 +811,11 @@ static void axienet_recv(struct net_device *ndev) cur_p->phys = dma_map_single(ndev->dev.parent, new_skb-quoted
data,lp->max_frm_size, DMA_FROM_DEVICE); + if (dma_mapping_error(ndev->dev.parent, cur_p->phys)) { + dev_kfree_skb(new_skb); + return; + } + cur_p->cntrl = lp->max_frm_size; cur_p->status = 0; cur_p->skb = new_skb; -- 2.17.1