Subject: Re: [PATCH iwl-net] ice: fix ice_parser_rt::bst_key array size

From: Simon Horman <[email-masked]>
Date: Thu, 12 Dec 2024 16:30:47 +0000

On Wed, Dec 11, 2024 at 02:26:36PM +0100, Przemek Kitszel wrote:
> Fix &ice_parser_rt::bst_key size. It was wrongly set to 10 instead of 20
> in the initial impl commit (see Fixes tag). All usage code assumed it was
> of size 20. That was also the initial size present up to v2 of the intro
> series [2], but halved by v3 [3] refactor described as "Replace magic
> hardcoded values with macros." The introducing series was so big that
> some ugliness was unnoticed, same for bugs :/
> 
> ICE_BST_KEY_TCAM_SIZE and ICE_BST_TCAM_KEY_SIZE were differing by one.
> There was tmp variable @j in the scope of edited function, but was not
> used in all places. This ugliness is now gone.
> I'm moving ice_parser_rt::pg_prio a few positions up, to fill up one of
> the holes in order to compensate for the added 10 bytes to the ::bst_key,
> resulting in the same size of the whole as prior to the fix, and miminal
> changes in the offsets of the fields.
> 
> This fix obsoletes Ahmed's attempt at [1].
> 
> [1] https://lore.kernel.org/intel-wired-lan/[email-masked]
> [2] https://lore.kernel.org/intel-wired-lan/[email-masked]
> [3] https://lore.kernel.org/intel-wired-lan/[email-masked]
> 
> Reported-by: Dan Carpenter <[email-masked]>
> Closes: https://lore.kernel.org/intel-wired-lan/[email-masked]
> Fixes: 9a4c07aaa0f5 ("ice: add parser execution main loop")
> CC: Ahmed Zaki <[email-masked]>
> Reviewed-by: Larysa Zaremba <[email-masked]>
> Signed-off-by: Przemek Kitszel <[email-masked]>

Hi Przemek,

I agree that these changes are good.  But I wonder if it would be best to
only treat the update size of bst_key as a fix.

...

> diff --git a/drivers/net/ethernet/intel/ice/ice_parser_rt.c b/drivers/net/ethernet/intel/ice/ice_parser_rt.c
> index dedf5e854e4b..d9c38ce27e4f 100644
> --- a/drivers/net/ethernet/intel/ice/ice_parser_rt.c
> +++ b/drivers/net/ethernet/intel/ice/ice_parser_rt.c
> @@ -125,22 +125,20 @@ static void ice_bst_key_init(struct ice_parser_rt *rt,
>  	else
>  		key[idd] = imem->b_kb.prio;
>  
> -	idd = ICE_BST_KEY_TCAM_SIZE - 1;
> +	idd = ICE_BST_TCAM_KEY_SIZE - 2;
>  	for (i = idd; i >= 0; i--) {
>  		int j;
>  
>  		j = ho + idd - i;
>  		if (j < ICE_PARSER_MAX_PKT_LEN)
> -			key[i] = rt->pkt_buf[ho + idd - i];
> +			key[i] = rt->pkt_buf[j];
>  		else
>  			key[i] = 0;
>  	}
>  
> -	ice_debug(rt->psr->hw, ICE_DBG_PARSER, "Generated Boost TCAM Key:\n");
> -	ice_debug(rt->psr->hw, ICE_DBG_PARSER, "%02X %02X %02X %02X %02X %02X %02X %02X %02X %02X\n",
> -		  key[0], key[1], key[2], key[3], key[4],
> -		  key[5], key[6], key[7], key[8], key[9]);
> -	ice_debug(rt->psr->hw, ICE_DBG_PARSER, "\n");
> +	ice_debug_array_w_prefix(rt->psr->hw, ICE_DBG_PARSER,
> +				 KBUILD_MODNAME "Generated Boost TCAM Key",

Should there be a delimeter between KBUILD_MODNAME and "Generated ..." ?
e.g.:

				 KBUILD_MODNAME ": Generated Boost TCAM Key",

> +				 key, ICE_BST_TCAM_KEY_SIZE);
>  }
>  
>  static u16 ice_bit_rev_u16(u16 v, int len)
> 
> base-commit: 51a00be6a0994da2ba6b4ace3b7a0d9373b4b25e
> -- 
> 2.46.0
> 
>