From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: [PATCH 2/2] sky2: hand receive DMA mapping failures Date: Mon, 1 Feb 2010 15:45:41 -0800 Message-ID: <20100201154541.6e3b9a17@nehalam> References: <20100201154147.5bb0b2c7@nehalam> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: David Miller , Jarek Poplawski , Michael Breuer , netdev@vger.kernel.org To: Stephen Hemminger Return-path: Received: from mail.vyatta.com ([76.74.103.46]:48830 "EHLO mail.vyatta.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753283Ab0BAXpx (ORCPT ); Mon, 1 Feb 2010 18:45:53 -0500 In-Reply-To: <20100201154147.5bb0b2c7@nehalam> Sender: netdev-owner@vger.kernel.org List-ID: If receive buffer mapping failed, then it was possible to get stuck with unmapped receive buffer in DMA ring. This would be an extremely rare condition because the driver had just released the map for the last receive so it should be able to get another map again (in soft-irq). Signed-off-by: Stephen Hemminger --- Patch is against net-next. Not worth the risk for 2.6.33 or stable --- a/drivers/net/sky2.c 2010-02-01 10:18:12.575044064 -0800 +++ b/drivers/net/sky2.c 2010-02-01 10:18:16.975356378 -0800 @@ -1103,18 +1103,39 @@ static int sky2_rx_map_skb(struct pci_de int i; re->data_addr = pci_map_single(pdev, skb->data, size, PCI_DMA_FROMDEVICE); - if (unlikely(pci_dma_mapping_error(pdev, re->data_addr))) - return -EIO; + if (pci_dma_mapping_error(pdev, re->data_addr)) + goto mapping_error; pci_unmap_len_set(re, data_size, size); - for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) - re->frag_addr[i] = pci_map_page(pdev, - skb_shinfo(skb)->frags[i].page, - skb_shinfo(skb)->frags[i].page_offset, - skb_shinfo(skb)->frags[i].size, + for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { + skb_frag_t *frag = &skb_shinfo(skb)->frags[i]; + + re->frag_addr[i] = pci_map_page(pdev, frag->page, + frag->page_offset, + frag->size, PCI_DMA_FROMDEVICE); + + if (pci_dma_mapping_error(pdev, re->frag_addr[i])) + goto map_page_error; + } return 0; + +map_page_error: + while (--i >= 0) { + pci_unmap_page(pdev, re->frag_addr[i], + skb_shinfo(skb)->frags[i].size, + PCI_DMA_FROMDEVICE); + } + + pci_unmap_single(pdev, re->data_addr, pci_unmap_len(re, data_size), + PCI_DMA_FROMDEVICE); + +mapping_error: + if (net_ratelimit()) + dev_warn(&pdev->dev, "%s: rx mapping error\n", + skb->dev->name); + return -EIO; } static void sky2_rx_unmap_skb(struct pci_dev *pdev, struct rx_ring_info *re) @@ -2306,30 +2327,32 @@ static struct sk_buff *receive_new(struc struct rx_ring_info *re, unsigned int length) { - struct sk_buff *skb, *nskb; + struct sk_buff *skb; + struct rx_ring_info nre; unsigned hdr_space = sky2->rx_data_size; - /* Don't be tricky about reusing pages (yet) */ - nskb = sky2_rx_alloc(sky2); - if (unlikely(!nskb)) - return NULL; + nre.skb = sky2_rx_alloc(sky2); + if (unlikely(!nre.skb)) + goto nobuf; + + if (sky2_rx_map_skb(sky2->hw->pdev, &nre, hdr_space)) + goto nomap; skb = re->skb; sky2_rx_unmap_skb(sky2->hw->pdev, re); - prefetch(skb->data); - re->skb = nskb; - if (sky2_rx_map_skb(sky2->hw->pdev, re, hdr_space)) { - dev_kfree_skb(nskb); - re->skb = skb; - return NULL; - } + *re = nre; if (skb_shinfo(skb)->nr_frags) skb_put_frags(skb, hdr_space, length); else skb_put(skb, length); return skb; + +nomap: + dev_kfree_skb(nre.skb); +nobuf: + return NULL; } /*