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be2net: dma_sync each RX frag before passing it to the stack

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The driver currently maps a page for DMA, divides the page into multiple
frags and posts them to the HW. It un-maps the page after data is received
on all the frags of the page. This scheme doesn't work when bounce buffers
are used for DMA (swiotlb=force kernel param).

This patch fixes this problem by calling dma_sync_single_for_cpu() for each
frag (excepting the last one) so that the data is copied from the bounce
buffers. The page is un-mapped only when DMA finishes on the last frag of
the page.
(Thanks Ben H. for suggesting the dma_sync API!)

This patch also renames the "last_page_user" field of be_rx_page_info{}
struct to "last_frag" to improve readability of the fixed code.

Reported-by: Li Fengmao <li.fengmao@zte.com.cn>
Signed-off-by: Sathya Perla <sathya.perla@emulex.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Sathya Perla 2014-03-04 12:14:38 +05:30 committed by David S. Miller
parent 9e82e7f4af
commit e50287be7c
2 changed files with 24 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
drivers/net/ethernet/emulex/benet/be.h
View File

@ -261,9 +261,10 @@ struct be_tx_obj {
/* Struct to remember the pages posted for rx frags */
struct be_rx_page_info {
struct page *page;
/* set to page-addr for last frag of the page & frag-addr otherwise */
DEFINE_DMA_UNMAP_ADDR(bus);
u16 page_offset;
bool last_page_user;
bool last_frag; /* last frag of the page */
};
struct be_rx_stats {

32
drivers/net/ethernet/emulex/benet/be_main.c
View File

@ -1448,11 +1448,15 @@ 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) {
if (rx_page_info->last_frag) {
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;
rx_page_info->last_frag = false;
} else {
dma_sync_single_for_cpu(&adapter->pdev->dev,
dma_unmap_addr(rx_page_info, bus),
rx_frag_size, DMA_FROM_DEVICE);
}
queue_tail_inc(rxq);
@ -1786,17 +1790,16 @@ static void be_post_rx_frags(struct be_rx_obj *rxo, gfp_t gfp)
rx_stats(rxo)->rx_post_fail++;
break;
}
page_info->page_offset = 0;
page_offset = 0;
} else {
get_page(pagep);
page_info->page_offset = page_offset + rx_frag_size;
page_offset += rx_frag_size;
}
page_offset = page_info->page_offset;
page_info->page_offset = page_offset;
page_info->page = pagep;
dma_unmap_addr_set(page_info, bus, page_dmaaddr);
frag_dmaaddr = page_dmaaddr + page_info->page_offset;
rxd = queue_head_node(rxq);
frag_dmaaddr = page_dmaaddr + page_info->page_offset;
rxd->fragpa_lo = cpu_to_le32(frag_dmaaddr & 0xFFFFFFFF);
rxd->fragpa_hi = cpu_to_le32(upper_32_bits(frag_dmaaddr));
@ -1804,15 +1807,24 @@ static void be_post_rx_frags(struct be_rx_obj *rxo, gfp_t gfp)
if ((page_offset + rx_frag_size + rx_frag_size) >
adapter->big_page_size) {
pagep = NULL;
page_info->last_page_user = true;
page_info->last_frag = true;
dma_unmap_addr_set(page_info, bus, page_dmaaddr);
} else {
dma_unmap_addr_set(page_info, bus, frag_dmaaddr);
}
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;
/* Mark the last frag of a page when we break out of the above loop
* with no more slots available in the RXQ
*/
if (pagep) {
prev_page_info->last_frag = true;
dma_unmap_addr_set(prev_page_info, bus, page_dmaaddr);
}
if (posted) {
atomic_add(posted, &rxq->used);