netdev - Re: [ovs-dev] [RFC PATCH 1/7] net: openvswitch: Move NSH buffer out of do_execute

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Message-ID: <8dc83d57-3e92-1d50-321c-fff6fde58bac@ovn.org>
Date: Wed, 27 Sep 2023 10:26:32 +0200
From: Ilya Maximets <i.maximets@....org>
To: Nicholas Piggin <npiggin@...il.com>, netdev@...r.kernel.org
Cc: dev@...nvswitch.org, i.maximets@....org
Subject: Re: [ovs-dev] [RFC PATCH 1/7] net: openvswitch: Move NSH buffer out
 of do_execute_actions

On 9/27/23 02:13, Nicholas Piggin wrote:
> This takes do_execute_actions stack use from 544 bytes to 288
> bytes. execute_push_nsh uses 336 bytes, but it is a leaf call not
> involved in recursion.
> 
> Signed-off-by: Nicholas Piggin <npiggin@...il.com>
> ---
>  net/openvswitch/actions.c | 27 +++++++++++++++++----------
>  1 file changed, 17 insertions(+), 10 deletions(-)

Hi, Nicholas.  I made the same change about a week ago:
  https://lore.kernel.org/netdev/20230921194314.1976605-1-i.maximets@ovn.org/
So, you can drop this patch from your set.

Best regards, Ilya Maximets.

> 
> diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c
> index fd66014d8a76..8933caa92794 100644
> --- a/net/openvswitch/actions.c
> +++ b/net/openvswitch/actions.c
> @@ -1286,6 +1286,21 @@ static int execute_dec_ttl(struct sk_buff *skb, struct sw_flow_key *key)
>  	return 0;
>  }
>  
> +static noinline_for_stack int execute_push_nsh(struct sk_buff *skb,
> +					       struct sw_flow_key *key,
> +					       const struct nlattr *attr)
> +{
> +	u8 buffer[NSH_HDR_MAX_LEN];
> +	struct nshhdr *nh = (struct nshhdr *)buffer;
> +	int err;
> +
> +	err = nsh_hdr_from_nlattr(attr, nh, NSH_HDR_MAX_LEN);
> +	if (likely(!err))
> +		err = push_nsh(skb, key, nh);
> +
> +	return err;
> +}
> +
>  /* Execute a list of actions against 'skb'. */
>  static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
>  			      struct sw_flow_key *key,
> @@ -1439,17 +1454,9 @@ static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
>  			err = pop_eth(skb, key);
>  			break;
>  
> -		case OVS_ACTION_ATTR_PUSH_NSH: {
> -			u8 buffer[NSH_HDR_MAX_LEN];
> -			struct nshhdr *nh = (struct nshhdr *)buffer;
> -
> -			err = nsh_hdr_from_nlattr(nla_data(a), nh,
> -						  NSH_HDR_MAX_LEN);
> -			if (unlikely(err))
> -				break;
> -			err = push_nsh(skb, key, nh);
> +		case OVS_ACTION_ATTR_PUSH_NSH:
> +			err = execute_push_nsh(skb, key, nla_data(a));
>  			break;
> -		}
>  
>  		case OVS_ACTION_ATTR_POP_NSH:
>  			err = pop_nsh(skb, key);