Subject: Re: [PATCH net v2 1/2] ixgbe: Allow flow hash to be set via ethtool

From: Joe Damato <[email-masked]>
Date: Sun, 16 Apr 2023 21:57:34 -0700

On Sun, Apr 16, 2023 at 07:12:22PM +0000, Joe Damato wrote:
> ixgbe currently returns `EINVAL` whenever the flowhash it set by ethtool
> because the ethtool code in the kernel passes a non-zero value for hfunc
> that ixgbe should allow.
> 
> When ethtool is called with `ETHTOOL_SRXFHINDIR`,
> `ethtool_set_rxfh_indir` will call ixgbe's set_rxfh function
> with `ETH_RSS_HASH_NO_CHANGE`. This value should be accepted.
> 
> When ethtool is called with `ETHTOOL_SRSSH`, `ethtool_set_rxfh` will
> call ixgbe's set_rxfh function with `rxfh.hfunc`, which appears to be
> hardcoded in ixgbe to always be `ETH_RSS_HASH_TOP`. This value should
> also be accepted.
> 
> Before this patch:
> 
> $ sudo ethtool -L eth1 combined 10
> $ sudo ethtool -X eth1 default
> Cannot set RX flow hash configuration: Invalid argument
> 
> After this patch:
> 
> $ sudo ethtool -L eth1 combined 10
> $ sudo ethtool -X eth1 default
> $ sudo ethtool -x eth1
> RX flow hash indirection table for eth1 with 10 RX ring(s):
>     0:      0     1     2     3     4     5     6     7
>     8:      8     9     0     1     2     3     4     5
>    16:      6     7     8     9     0     1     2     3
>    24:      4     5     6     7     8     9     0     1
>    ...
> 

Sorry for the noise, forgot the fixes tag.

Fixes: 1c7cf0784e4d ("ixgbe: support for ethtool set_rxfh")

> Signed-off-by: Joe Damato <[email-masked]>
> Reviewed-by: Sridhar Samudrala <[email-masked]>
> ---
>  drivers/net/ethernet/intel/ixgbe/ixgbe_ethtool.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_ethtool.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_ethtool.c
> index 6cfc9dc16537..821dfd323fa9 100644
> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_ethtool.c
> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_ethtool.c
> @@ -3131,8 +3131,8 @@ static int ixgbe_set_rxfh(struct net_device *netdev, const u32 *indir,
>  	int i;
>  	u32 reta_entries = ixgbe_rss_indir_tbl_entries(adapter);
>  
> -	if (hfunc)
> -		return -EINVAL;
> +	if (hfunc != ETH_RSS_HASH_NO_CHANGE && hfunc != ETH_RSS_HASH_TOP)
> +		return -EOPNOTSUPP;
>  
>  	/* Fill out the redirection table */
>  	if (indir) {
> -- 
> 2.25.1
>