Subject: Re: [PATCH net v2 1/2] sfc: use 64-bit writes for PIO.

From: Shradha Shah <[email-masked]>
Date: Wed, 28 May 2014 10:32:30 +0100

Please ignore this patch.

I have sent out the correct patch with a cover letter.

My Apologies for duplication

Regards,
Shradha

On 28/05/14 10:27, Shradha Shah wrote:
> From: Jon Cooper <[email-masked]>
> 
> Patch to open-code the memory copy routines.
> 32bit writes over the PCI bus causes data corruption.
> 
> Fixes:ee45fd92c739db5b7950163d91dfe5f016af6d24
> 
> orig-hg-hash: 853f313def1e5e9c733f980f2b4e6330a7d063ef
> Signed-off-by: Shradha Shah <[email-masked]>
> ---
>  drivers/net/ethernet/sfc/tx.c | 24 +++++++++++++++++++-----
>  1 file changed, 19 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/net/ethernet/sfc/tx.c b/drivers/net/ethernet/sfc/tx.c
> index fa94753..bd6a4b8 100644
> --- a/drivers/net/ethernet/sfc/tx.c
> +++ b/drivers/net/ethernet/sfc/tx.c
> @@ -189,6 +189,20 @@ struct efx_short_copy_buffer {
>  	u8 buf[L1_CACHE_BYTES];
>  };
>  
> +/* Copy in explicit 64-bit writes. */
> +static void efx_memcpy_64(void *dest, void *src, size_t len)
> +{
> +	uint64_t *src64 = src, *dest64 = dest;
> +	size_t i, l64 = len / 8;
> +
> +	WARN_ON_ONCE(len % 8 != 0);
> +	WARN_ON_ONCE(((u8 *)dest - (u8 *) 0) % 8 != 0);
> +	BUILD_BUG_ON(sizeof(uint64_t) != 8);
> +
> +	for(i = 0; i < l64; ++i)
> +		dest64[i] = src64[i];
> +}
> +
>  /* Copy to PIO, respecting that writes to PIO buffers must be dword aligned.
>   * Advances piobuf pointer. Leaves additional data in the copy buffer.
>   */
> @@ -198,7 +212,7 @@ static void efx_memcpy_toio_aligned(struct efx_nic *efx, u8 __iomem **piobuf,
>  {
>  	int block_len = len & ~(sizeof(copy_buf->buf) - 1);
>  
> -	memcpy_toio(*piobuf, data, block_len);
> +	efx_memcpy_64(*piobuf, data, block_len);
>  	*piobuf += block_len;
>  	len -= block_len;
>  
> @@ -230,7 +244,7 @@ static void efx_memcpy_toio_aligned_cb(struct efx_nic *efx, u8 __iomem **piobuf,
>  		if (copy_buf->used < sizeof(copy_buf->buf))
>  			return;
>  
> -		memcpy_toio(*piobuf, copy_buf->buf, sizeof(copy_buf->buf));
> +		efx_memcpy_64(*piobuf, copy_buf->buf, sizeof(copy_buf->buf));
>  		*piobuf += sizeof(copy_buf->buf);
>  		data += copy_to_buf;
>  		len -= copy_to_buf;
> @@ -245,7 +259,7 @@ static void efx_flush_copy_buffer(struct efx_nic *efx, u8 __iomem *piobuf,
>  {
>  	/* if there's anything in it, write the whole buffer, including junk */
>  	if (copy_buf->used)
> -		memcpy_toio(piobuf, copy_buf->buf, sizeof(copy_buf->buf));
> +		efx_memcpy_64(piobuf, copy_buf->buf, sizeof(copy_buf->buf));
>  }
>  
>  /* Traverse skb structure and copy fragments in to PIO buffer.
> @@ -304,8 +318,8 @@ efx_enqueue_skb_pio(struct efx_tx_queue *tx_queue, struct sk_buff *skb)
>  		 */
>  		BUILD_BUG_ON(L1_CACHE_BYTES >
>  			     SKB_DATA_ALIGN(sizeof(struct skb_shared_info)));
> -		memcpy_toio(tx_queue->piobuf, skb->data,
> -			    ALIGN(skb->len, L1_CACHE_BYTES));
> +		efx_memcpy_64(tx_queue->piobuf, skb->data,
> +			      ALIGN(skb->len, L1_CACHE_BYTES));
>  	}
>  
>  	EFX_POPULATE_QWORD_5(buffer->option,
> 

-- 
Many Thanks,
Regards,
Shradha Shah