Return-path: Received: from mail-pa0-f50.google.com ([209.85.220.50]:56349 "EHLO mail-pa0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750904Ab2L0Uiz (ORCPT ); Thu, 27 Dec 2012 15:38:55 -0500 Message-ID: <50DCB1D9.50906@lwfinger.net> (sfid-20121227_213910_507642_03ACCF0B) Date: Thu, 27 Dec 2012 14:38:49 -0600 From: Larry Finger MIME-Version: 1.0 To: Eric Dumazet CC: linville@tuxdriver.com, davem@davemloft.net, linux-wireless@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] forcedeth: Fix WARNINGS that result when DMA mapping is not checked References: <1356637327-4884-1-git-send-email-Larry.Finger@lwfinger.net> <1356638715.30414.1349.camel@edumazet-glaptop> In-Reply-To: <1356638715.30414.1349.camel@edumazet-glaptop> Content-Type: text/plain; charset=UTF-8; format=flowed Sender: linux-wireless-owner@vger.kernel.org List-ID: On 12/27/2012 02:05 PM, Eric Dumazet wrote: > On Thu, 2012-12-27 at 13:42 -0600, Larry Finger wrote: >> With 3.8-rc1, the first call of pci_map_single() that is not checked >> with a corresponding pci_dma_mapping_error() call results in a warning >> with a splat as follows: >> >> WARNING: at lib/dma-debug.c:933 check_unmap+0x480/0x950() >> Hardware name: HP Pavilion dv2700 Notebook PC >> forcedeth 0000:00:0a.0: DMA-API: device driver failed to check >> map error[device address=0x00000000b176e002] [size=90 bytes] [mapped as single] >> >> Signed-off-by: Larry Finger >> --- >> drivers/net/ethernet/nvidia/forcedeth.c | 23 +++++++++++++++++++++++ >> 1 file changed, 23 insertions(+) >> >> diff --git a/drivers/net/ethernet/nvidia/forcedeth.c b/drivers/net/ethernet/nvidia/forcedeth.c >> index 653487d..de39cf2 100644 >> --- a/drivers/net/ethernet/nvidia/forcedeth.c >> +++ b/drivers/net/ethernet/nvidia/forcedeth.c >> @@ -1821,6 +1821,11 @@ static int nv_alloc_rx(struct net_device *dev) >> skb->data, >> skb_tailroom(skb), >> PCI_DMA_FROMDEVICE); >> + if (pci_dma_mapping_error(np->pci_dev, >> + np->put_rx_ctx->dma)) { >> + dev_kfree_skb_any(skb); > > skb has no destructor yet, kfree_skb(skb) should be fine OK. > >> + goto packet_dropped; >> + } >> np->put_rx_ctx->dma_len = skb_tailroom(skb); >> np->put_rx.orig->buf = cpu_to_le32(np->put_rx_ctx->dma); >> wmb(); >> @@ -1830,6 +1835,7 @@ static int nv_alloc_rx(struct net_device *dev) >> if (unlikely(np->put_rx_ctx++ == np->last_rx_ctx)) >> np->put_rx_ctx = np->first_rx_ctx; >> } else { >> +packet_dropped: >> u64_stats_update_begin(&np->swstats_rx_syncp); >> np->stat_rx_dropped++; >> u64_stats_update_end(&np->swstats_rx_syncp); >> @@ -1856,6 +1862,11 @@ static int nv_alloc_rx_optimized(struct net_device *dev) >> skb->data, >> skb_tailroom(skb), >> PCI_DMA_FROMDEVICE); >> + if (pci_dma_mapping_error(np->pci_dev, >> + np->put_rx_ctx->dma)) { >> + dev_kfree_skb_any(skb); >> + goto packet_dropped; >> + } >> np->put_rx_ctx->dma_len = skb_tailroom(skb); >> np->put_rx.ex->bufhigh = cpu_to_le32(dma_high(np->put_rx_ctx->dma)); >> np->put_rx.ex->buflow = cpu_to_le32(dma_low(np->put_rx_ctx->dma)); >> @@ -1866,6 +1877,7 @@ static int nv_alloc_rx_optimized(struct net_device *dev) >> if (unlikely(np->put_rx_ctx++ == np->last_rx_ctx)) >> np->put_rx_ctx = np->first_rx_ctx; >> } else { >> +packet_dropped: >> u64_stats_update_begin(&np->swstats_rx_syncp); >> np->stat_rx_dropped++; >> u64_stats_update_end(&np->swstats_rx_syncp); >> @@ -2217,6 +2229,9 @@ static netdev_tx_t nv_start_xmit(struct sk_buff *skb, struct net_device *dev) >> bcnt = (size > NV_TX2_TSO_MAX_SIZE) ? NV_TX2_TSO_MAX_SIZE : size; >> np->put_tx_ctx->dma = pci_map_single(np->pci_dev, skb->data + offset, bcnt, >> PCI_DMA_TODEVICE); >> + if (pci_dma_mapping_error(np->pci_dev, >> + np->put_tx_ctx->dma)) >> + return NETDEV_TX_BUSY; > > Really this is not going to work very well : caller will call this in a > loop. Any suggestions on what value should be returned, or does the caller need to be modified? Thanks for the review, Larry