Re: [PATCH] intel: igb: igb_ethtool.c: Convert kmap() to kmap_local_page()

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

On Fri, Apr 15, 2022 at 10:53:07PM +0200, Alaa Mohamed wrote:
> The use of kmap() is being deprecated in favor of kmap_local_page()
> where it is feasible.
> 
> With kmap_local_page(), the mapping is per thread, CPU local and not
> globally visible.
> 
> Signed-off-by: Alaa Mohamed <eng.alaamohamedsoliman.am@gmail.com>
> ---
>  drivers/net/ethernet/intel/igb/igb_ethtool.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/igb/igb_ethtool.c b/drivers/net/ethernet/intel/igb/igb_ethtool.c
> index 2a5782063f4c..ba93aa4ae6a0 100644
> --- a/drivers/net/ethernet/intel/igb/igb_ethtool.c
> +++ b/drivers/net/ethernet/intel/igb/igb_ethtool.c
> @@ -1798,14 +1798,14 @@ static int igb_check_lbtest_frame(struct igb_rx_buffer *rx_buffer,
>  
>  	frame_size >>= 1;
>  
> -	data = kmap(rx_buffer->page);
> +	data = kmap_local_page(rx_buffer->page);
>  
>  	if (data[3] != 0xFF ||
>  	    data[frame_size + 10] != 0xBE ||
>  	    data[frame_size + 12] != 0xAF)
>  		match = false;
>  
> -	kunmap(rx_buffer->page);
> +	kunmap_local(rx_buffer->page);

kunmap_local() is different from kunmap().  It takes an address within the
mapped page.  From the kdoc:

/**
 * kunmap_local - Unmap a page mapped via kmap_local_page().
 * @__addr: An address within the page mapped
 *
 * @__addr can be any address within the mapped page.  Commonly it is the
 * address return from kmap_local_page(), but it can also include offsets.
 *
 * Unmapping should be done in the reverse order of the mapping.  See
 * kmap_local_page() for details.
 */
#define kunmap_local(__addr)                                    \
...


Ira

>  
>  	return match;
>  }
> -- 
> 2.35.2
>