sfc: Fix efx_rx_buf_offset() in the presence of swiotlb

We assume that the mapping between DMA and virtual addresses is done
on whole pages, so we can find the page offset of an RX buffer using
the lower bits of the DMA address.  However, swiotlb maps in units of
2K, breaking this assumption.

Add an explicit page_offset field to struct efx_rx_buffer.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>

diff --git a/drivers/net/ethernet/sfc/net_driver.h b/drivers/net/ethernet/sfc/net_driver.h
index 2d756c1d71425823100f572065e224a59ca16813..0a90abd2421b62540d7e2fb2888caa0a4a3abf3a 100644 (file)
--- a/drivers/net/ethernet/sfc/net_driver.h
+++ b/drivers/net/ethernet/sfc/net_driver.h
@@ -210,6 +210,7 @@ struct efx_tx_queue {
  *     Will be %NULL if the buffer slot is currently free.
  * @page: The associated page buffer. Valif iff @flags & %EFX_RX_BUF_PAGE.
  *     Will be %NULL if the buffer slot is currently free.
+ * @page_offset: Offset within page. Valid iff @flags & %EFX_RX_BUF_PAGE.
  * @len: Buffer length, in bytes.
  * @flags: Flags for buffer and packet state.
  */
@@ -219,7 +220,8 @@ struct efx_rx_buffer {
                struct sk_buff *skb;
                struct page *page;
        } u;
-       unsigned int len;
+       u16 page_offset;
+       u16 len;
        u16 flags;
 };
 #define EFX_RX_BUF_PAGE                0x0001

diff --git a/drivers/net/ethernet/sfc/rx.c b/drivers/net/ethernet/sfc/rx.c
index a5754916478e46e9eeebdcf5df637c090863a374..879ff5849bbd181e58e9d5be8e75f28d89f2ddad 100644 (file)
--- a/drivers/net/ethernet/sfc/rx.c
+++ b/drivers/net/ethernet/sfc/rx.c
@@ -90,11 +90,7 @@ static unsigned int rx_refill_threshold;
 static inline unsigned int efx_rx_buf_offset(struct efx_nic *efx,
                                             struct efx_rx_buffer *buf)
 {
-       /* Offset is always within one page, so we don't need to consider
-        * the page order.
-        */
-       return ((unsigned int) buf->dma_addr & (PAGE_SIZE - 1)) +
-               efx->type->rx_buffer_hash_size;
+       return buf->page_offset + efx->type->rx_buffer_hash_size;
 }
 static inline unsigned int efx_rx_buf_size(struct efx_nic *efx)
 {
@@ -187,6 +183,7 @@ static int efx_init_rx_buffers_page(struct efx_rx_queue *rx_queue)
        struct efx_nic *efx = rx_queue->efx;
        struct efx_rx_buffer *rx_buf;
        struct page *page;
+       unsigned int page_offset;
        struct efx_rx_page_state *state;
        dma_addr_t dma_addr;
        unsigned index, count;
@@ -211,12 +208,14 @@ static int efx_init_rx_buffers_page(struct efx_rx_queue *rx_queue)
                state->dma_addr = dma_addr;
 
                dma_addr += sizeof(struct efx_rx_page_state);
+               page_offset = sizeof(struct efx_rx_page_state);
 
        split:
                index = rx_queue->added_count & rx_queue->ptr_mask;
                rx_buf = efx_rx_buffer(rx_queue, index);
                rx_buf->dma_addr = dma_addr + EFX_PAGE_IP_ALIGN;
                rx_buf->u.page = page;
+               rx_buf->page_offset = page_offset;
                rx_buf->len = efx->rx_buffer_len - EFX_PAGE_IP_ALIGN;
                rx_buf->flags = EFX_RX_BUF_PAGE;
                ++rx_queue->added_count;
@@ -227,6 +226,7 @@ static int efx_init_rx_buffers_page(struct efx_rx_queue *rx_queue)
                        /* Use the second half of the page */
                        get_page(page);
                        dma_addr += (PAGE_SIZE >> 1);
+                       page_offset += (PAGE_SIZE >> 1);
                        ++count;
                        goto split;
                }