> prod_rx_buf->skb = skb;
> diff --git a/drivers/net/bnx2x/bnx2x_cmn.h b/drivers/net/bnx2x/bnx2x_cmn.h
> index c016e20..c9e49a0 100644
> --- a/drivers/net/bnx2x/bnx2x_cmn.h
> +++ b/drivers/net/bnx2x/bnx2x_cmn.h
> @@ -923,16 +923,11 @@ static inline int bnx2x_alloc_rx_skb(struct bnx2x
> *bp, static inline void bnx2x_reuse_rx_skb(struct bnx2x_fastpath *fp,
> u16 cons, u16 prod)
> {
> - struct bnx2x *bp = fp->bp;
> struct sw_rx_bd *cons_rx_buf = &fp->rx_buf_ring[cons];
> struct sw_rx_bd *prod_rx_buf = &fp->rx_buf_ring[prod];
> struct eth_rx_bd *cons_bd = &fp->rx_desc_ring[cons];
> struct eth_rx_bd *prod_bd = &fp->rx_desc_ring[prod];
>
> - dma_sync_single_for_device(&bp->pdev->dev,
> - dma_unmap_addr(cons_rx_buf, mapping),
> - RX_COPY_THRESH, DMA_FROM_DEVICE);
> -
> dma_unmap_addr_set(prod_rx_buf, mapping,
> dma_unmap_addr(cons_rx_buf, mapping));
> prod_rx_buf->skb = cons_rx_buf->skb;
Michal, pls., note that this function is only called for buffers which were
previously dma_synced towards CPU (your "[PATCH v2 05/46] net: bnx2x: fix DMA
sync direction" properly fixes the direction of the first call which was
incorrect). Then, according to the 3d edition of the "Linux device drivers"
book, chapter 15, "Setting up streaming DMA mappings" article, end of the page
449, when we call for dma_syc_single_for_cpu() the buffer ownership gets to
the CPU and CPU may safely access the buffer (in particular, we read it). Then
the author says: "Before the device accesses the buffer, however, ownership
should be transfered back to it with: dma_sync_single_for_device().
The DMA-API.txt document u've referenced doesn't refer the above function, so,
it's unclear how your fix may be based on it. On the other hand it clearly
contradicts the "Linux device driver" book.
Pls., comment.
thanks,
vlad
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