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Date: Thu, 20 Feb 2014 09:39:53 +0000
From: Sathya Perla <Sathya.Perla@...lex.Com>
To: "jiang.biao2@....com.cn" <jiang.biao2@....com.cn>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>
CC: Subramanian Seetharaman <subbu.seetharaman@...lex.com>,
Ajit Khaparde <Ajit.Khaparde@...lex.Com>,
"wang.liang82@....com.cn" <wang.liang82@....com.cn>,
"cai.qu@....com.cn" <cai.qu@....com.cn>,
"li.fengmao@....com.cn" <li.fengmao@....com.cn>,
"long.chun@....com.cn" <long.chun@....com.cn>,
David Miller <davem@...emloft.net>
Subject: RE: [PATCH] be2net: Bugfix for packet drop with kernel param
swiotlb=force
> -----Original Message-----
> From: jiang.biao2@....com.cn [mailto:jiang.biao2@....com.cn]
>
>
> From: Li Fengmao <li.fengmao@....com.cn>
>
> There will be packet drop with kernel param "swiotlb = force" on
> Emulex 10Gb NIC using be2net driver. The problem is caused by
> receiving skb without calling pci_unmap_page() in get_rx_page_info().
> rx_page_info->last_page_user is initialized to false in
> be_post_rx_frags() when current frag are mapped in the first half of
> the same page with another frag. But in that case with
> "swiotlb = force" param, data can not be copied into the page of
> rx_page_info without calling pci_unmap_page, so the data frag mapped
> in the first half of the page will be dropped.
>
> It can be solved by creating only a mapping relation between frag
> and page, and deleting rx_page_info->last_page_user to ensure
> calling pci_unmap_page when handling each receiving frag.
This patch uses an entire page for each RX frag (whose default size is 2048).
Consequently, on platforms like ppc64 where the default PAGE_SIZE is 64K,
memory usage becomes very inefficient.
Instead, I've tried a partial-page mapping scheme. This retains the
page sharing logic, but un-maps each frag separately so that
the data is copied from the bounce buffers.
Pls see if this works for you; thanks.
---
diff --git a/drivers/net/ethernet/emulex/benet/be.h b/drivers/net/ethernet/emulex/benet/be.h
index a150401..013777a 100644
--- a/drivers/net/ethernet/emulex/benet/be.h
+++ b/drivers/net/ethernet/emulex/benet/be.h
@@ -263,7 +263,6 @@ struct be_rx_page_info {
struct page *page;
DEFINE_DMA_UNMAP_ADDR(bus);
u16 page_offset;
- bool last_page_user;
};
struct be_rx_stats {
diff --git a/drivers/net/ethernet/emulex/benet/be_main.c b/drivers/net/ethernet/emulex/benet/be_main.c
index 4f87f5c..9d8ea91 100644
--- a/drivers/net/ethernet/emulex/benet/be_main.c
+++ b/drivers/net/ethernet/emulex/benet/be_main.c
@@ -1448,13 +1448,8 @@ static struct be_rx_page_info *get_rx_page_info(struct be_rx_obj *rxo)
rx_page_info = &rxo->page_info_tbl[frag_idx];
BUG_ON(!rx_page_info->page);
- if (rx_page_info->last_page_user) {
- dma_unmap_page(&adapter->pdev->dev,
- dma_unmap_addr(rx_page_info, bus),
- adapter->big_page_size, DMA_FROM_DEVICE);
- rx_page_info->last_page_user = false;
- }
-
+ dma_unmap_page(&adapter->pdev->dev, dma_unmap_addr(rx_page_info, bus),
+ rx_frag_size, DMA_FROM_DEVICE);
queue_tail_inc(rxq);
atomic_dec(&rxq->used);
return rx_page_info;
@@ -1761,12 +1756,12 @@ static inline struct page *be_alloc_pages(u32 size, gfp_t gfp)
static void be_post_rx_frags(struct be_rx_obj *rxo, gfp_t gfp)
{
struct be_adapter *adapter = rxo->adapter;
- struct be_rx_page_info *page_info = NULL, *prev_page_info = NULL;
+ struct be_rx_page_info *page_info = NULL;
struct be_queue_info *rxq = &rxo->q;
struct page *pagep = NULL;
struct device *dev = &adapter->pdev->dev;
struct be_eth_rx_d *rxd;
- u64 page_dmaaddr = 0, frag_dmaaddr;
+ u64 frag_dmaaddr;
u32 posted, page_offset = 0;
page_info = &rxo->page_info_tbl[rxq->head];
@@ -1777,24 +1772,22 @@ static void be_post_rx_frags(struct be_rx_obj *rxo, gfp_t gfp)
rx_stats(rxo)->rx_post_fail++;
break;
}
- page_dmaaddr = dma_map_page(dev, pagep, 0,
- adapter->big_page_size,
- DMA_FROM_DEVICE);
- if (dma_mapping_error(dev, page_dmaaddr)) {
- put_page(pagep);
- pagep = NULL;
- rx_stats(rxo)->rx_post_fail++;
- break;
- }
page_info->page_offset = 0;
} else {
get_page(pagep);
page_info->page_offset = page_offset + rx_frag_size;
}
page_offset = page_info->page_offset;
+
+ frag_dmaaddr = dma_map_page(dev, pagep, page_offset,
+ rx_frag_size, DMA_FROM_DEVICE);
+ if (dma_mapping_error(dev, frag_dmaaddr)) {
+ put_page(pagep);
+ rx_stats(rxo)->rx_post_fail++;
+ break;
+ }
page_info->page = pagep;
- dma_unmap_addr_set(page_info, bus, page_dmaaddr);
- frag_dmaaddr = page_dmaaddr + page_info->page_offset;
+ dma_unmap_addr_set(page_info, bus, frag_dmaaddr);
rxd = queue_head_node(rxq);
rxd->fragpa_lo = cpu_to_le32(frag_dmaaddr & 0xFFFFFFFF);
@@ -1802,17 +1795,12 @@ static void be_post_rx_frags(struct be_rx_obj *rxo, gfp_t gfp)
/* Any space left in the current big page for another frag? */
if ((page_offset + rx_frag_size + rx_frag_size) >
- adapter->big_page_size) {
+ adapter->big_page_size)
pagep = NULL;
- page_info->last_page_user = true;
- }
- prev_page_info = page_info;
queue_head_inc(rxq);
page_info = &rxo->page_info_tbl[rxq->head];
}
- if (pagep)
- prev_page_info->last_page_user = true;
if (posted) {
atomic_add(posted, &rxq->used);
>
> Steps to reproduce the bug:
> 1. Prepare a Emulex Corporation OneConnect 10Gb NIC.
> 2. Add the kernel param like "swiotlb = force" in /boot/grub/grub.conf .
> 3. Reboot the system. (e.g exec reboot command)
> 4. Activate the interface. (e.g ifconfig eth0 192.168.1.2 up)
> 5. There will be packet drop when ping 192.168.1.2 from another host.
>
> Signed-off-by: Li Fengmao <li.fengmao@....com.cn>
> Signed-off-by: Long Chun <long.chun@....com.cn>
> Reviewed-by: Wang Liang <wang.liang82@....com.cn>
> Reviewed-by: Cai Qu <cai.qu@....com.cn>
> Reviewed-by: Jiang Biao <jiang.biao2@....com.cn>
>
> --- old/drivers/net/ethernet/emulex/benet/be_main.c 2014-02-20
> 08:49:49.322503588 +0800
> +++ new/drivers/net/ethernet/emulex/benet/be_main.c 2014-02-20
> 08:56:38.796503104 +0800
> @@ -1018,12 +1018,9 @@ get_rx_page_info(struct be_adapter *adap
> rx_page_info = &rxo->page_info_tbl[frag_idx];
> BUG_ON(!rx_page_info->page);
>
> - if (rx_page_info->last_page_user) {
> - dma_unmap_page(&adapter->pdev->dev,
> - dma_unmap_addr(rx_page_info, bus),
> - adapter->big_page_size, DMA_FROM_DEVICE);
> - rx_page_info->last_page_user = false;
> - }
> + dma_unmap_page(&adapter->pdev->dev,
> + dma_unmap_addr(rx_page_info, bus),
> + rx_frag_size, DMA_FROM_DEVICE);
>
> atomic_dec(&rxq->used);
> return rx_page_info;
> @@ -1344,20 +1341,15 @@ static void be_post_rx_frags(struct be_r
>
> page_info = &rxo->page_info_tbl[rxq->head];
> for (posted = 0; posted < MAX_RX_POST && !page_info->page; posted++) {
> - if (!pagep) {
> - pagep = be_alloc_pages(adapter->big_page_size, gfp);
> - if (unlikely(!pagep)) {
> - rx_stats(rxo)->rx_post_fail++;
> - break;
> - }
> - page_dmaaddr = dma_map_page(&adapter->pdev->dev, pagep,
> - 0, adapter->big_page_size,
> - DMA_FROM_DEVICE);
> - page_info->page_offset = 0;
> - } else {
> - get_page(pagep);
> - page_info->page_offset = page_offset + rx_frag_size;
> + pagep = be_alloc_pages(rx_frag_size, gfp);
> + if (unlikely(!pagep)) {
> + rx_stats(rxo)->rx_post_fail++;
> + break;
> }
> + page_dmaaddr = dma_map_page(&adapter->pdev->dev, pagep,
> + 0, rx_frag_size,
> + DMA_FROM_DEVICE);
> + page_info->page_offset = 0;
> page_offset = page_info->page_offset;
> page_info->page = pagep;
> dma_unmap_addr_set(page_info, bus, page_dmaaddr);
> @@ -1367,12 +1359,7 @@ static void be_post_rx_frags(struct be_r
> rxd->fragpa_lo = cpu_to_le32(frag_dmaaddr & 0xFFFFFFFF);
> rxd->fragpa_hi = cpu_to_le32(upper_32_bits(frag_dmaaddr));
>
> - /* Any space left in the current big page for another frag? */
> - if ((page_offset + rx_frag_size + rx_frag_size) >
> - adapter->big_page_size) {
> - pagep = NULL;
> - page_info->last_page_user = true;
> - }
> + pagep = NULL;
>
> prev_page_info = page_info;
> queue_head_inc(rxq);
--
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