Re: [Intel-wired-lan] [RESEND PATCH net-next 1/2] e1000: Remove unnecessary use of kmap_atomic()

[Ira Weiny <ira.weiny@intel.com>]

On Mon, Sep 19, 2022 at 11:09:48AM -0700, Venkataramanan, Anirudh wrote:
> buffer_info->rxbuf.page accessed in e1000_clean_jumbo_rx_irq() is
> allocated using GFP_ATOMIC. Pages allocated with GFP_ATOMIC can't come from
> highmem and so there's no need to kmap() them. Just use page_address().
> 
> I don't have access to a 32-bit system so did some limited testing on
> qemu (qemu-system-i386 -m 4096 -smp 4 -device e1000e) with a 32-bit
> Debian 11.04 image.
> 
> Cc: Ira Weiny <ira.weiny@intel.com>
> Cc: Fabio M. De Francesco <fmdefrancesco@gmail.com>
> Cc: Jesse Brandeburg <jesse.brandeburg@intel.com>
> Cc: Tony Nguyen <anthony.l.nguyen@intel.com>
> Suggested-by: Ira Weiny <ira.weiny@intel.com>

Reviewed-by: Ira Weiny <ira.weiny@intel.com>

> Suggested-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
> Signed-off-by: Anirudh Venkataramanan <anirudh.venkataramanan@intel.com>
> ---
>  drivers/net/ethernet/intel/e1000/e1000_main.c | 9 +++------
>  1 file changed, 3 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/e1000/e1000_main.c b/drivers/net/ethernet/intel/e1000/e1000_main.c
> index 23299fc..93e57b1 100644
> --- a/drivers/net/ethernet/intel/e1000/e1000_main.c
> +++ b/drivers/net/ethernet/intel/e1000/e1000_main.c
> @@ -4229,8 +4229,6 @@ static bool e1000_clean_jumbo_rx_irq(struct e1000_adapter *adapter,
>  				 */
>  				p = buffer_info->rxbuf.page;
>  				if (length <= copybreak) {
> -					u8 *vaddr;
> -
>  					if (likely(!(netdev->features & NETIF_F_RXFCS)))
>  						length -= 4;
>  					skb = e1000_alloc_rx_skb(adapter,
> @@ -4238,10 +4236,9 @@ static bool e1000_clean_jumbo_rx_irq(struct e1000_adapter *adapter,
>  					if (!skb)
>  						break;
>  
> -					vaddr = kmap_atomic(p);
> -					memcpy(skb_tail_pointer(skb), vaddr,
> -					       length);
> -					kunmap_atomic(vaddr);
> +					memcpy(skb_tail_pointer(skb),
> +					       page_address(p), length);
> +
>  					/* re-use the page, so don't erase
>  					 * buffer_info->rxbuf.page
>  					 */
> -- 
> 2.37.2
> 
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