linux-kernel - Re: [PATCH] intel: igb: igb_ethtool.c: Convert kmap() to kmap_local

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Message-ID: <alpine.DEB.2.22.394.2204160937120.3501@hadrien>
Date:   Sat, 16 Apr 2022 09:37:33 +0200 (CEST)
From:   Julia Lawall <julia.lawall@...ia.fr>
To:     Alaa Mohamed <eng.alaamohamedsoliman.am@...il.com>
cc:     outreachy@...ts.linux.dev, jesse.brandeburg@...el.com,
        anthony.l.nguyen@...el.com, davem@...emloft.net, kuba@...nel.org,
        pabeni@...hat.com, intel-wired-lan@...ts.osuosl.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        ira.weiny@...el.com
Subject: Re: [PATCH] intel: igb: igb_ethtool.c: Convert kmap() to
 kmap_local_page()



On Fri, 15 Apr 2022, Alaa Mohamed wrote:

> The use of kmap() is being deprecated in favor of kmap_local_page()
> where it is feasible.

And why is it feasible here?

julia

>
> With kmap_local_page(), the mapping is per thread, CPU local and not
> globally visible.
>
> Signed-off-by: Alaa Mohamed <eng.alaamohamedsoliman.am@...il.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);
>
>  	return match;
>  }
> --
> 2.35.2
>
>
>