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From: David Ahern <dsahern@kernel•org>
To: Eric Dumazet <edumazet@google•com>,
	"David S . Miller" <davem@davemloft•net>,
	Jakub Kicinski <kuba@kernel•org>, Paolo Abeni <pabeni@redhat•com>
Cc: Soheil Hassas Yeganeh <soheil@google•com>,
	Neal Cardwell <ncardwell@google•com>,
	Yuchung Cheng <ycheng@google•com>,
	netdev@vger•kernel.org, eric.dumazet@gmail•com
Subject: Re: [PATCH net-next 3/3] tcp: derive delack_max from rto_min
Date: Wed, 20 Sep 2023 15:57:09 -0600	[thread overview]
Message-ID: <89a3cbd7-fd82-d925-b916-e323033ffdbe@kernel.org> (raw)
In-Reply-To: <20230920172943.4135513-4-edumazet@google.com>

On 9/20/23 11:29 AM, Eric Dumazet wrote:
> diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
> index 1fc1f879cfd6c28cd655bb8f02eff6624eec2ffc..2d1e4b5ac1ca41ff3db8dc58458d4e922a2c4999 100644
> --- a/net/ipv4/tcp_output.c
> +++ b/net/ipv4/tcp_output.c
> @@ -3977,6 +3977,20 @@ int tcp_connect(struct sock *sk)
>  }
>  EXPORT_SYMBOL(tcp_connect);
>  
> +u32 tcp_delack_max(const struct sock *sk)
> +{
> +	const struct dst_entry *dst = __sk_dst_get(sk);
> +	u32 delack_max = inet_csk(sk)->icsk_delack_max;
> +
> +	if (dst && dst_metric_locked(dst, RTAX_RTO_MIN)) {
> +		u32 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
> +		u32 delack_from_rto_min = max_t(int, 1, rto_min - 1);

`u32` type with max_t type set as `int`

> +
> +		delack_max = min_t(u32, delack_max, delack_from_rto_min);
> +	}
> +	return delack_max;
> +}
> +
>  /* Send out a delayed ack, the caller does the policy checking
>   * to see if we should even be here.  See tcp_input.c:tcp_ack_snd_check()
>   * for details.
> @@ -4012,7 +4026,7 @@ void tcp_send_delayed_ack(struct sock *sk)
>  		ato = min(ato, max_ato);
>  	}
>  
> -	ato = min_t(u32, ato, inet_csk(sk)->icsk_delack_max);
> +	ato = min_t(u32, ato, tcp_delack_max(sk));

and then here ato is an `int`.
>  
>  	/* Stay within the limit we were given */
>  	timeout = jiffies + ato;


  parent reply	other threads:[~2023-09-20 21:57 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-09-20 17:29 [PATCH net-next 0/3] tcp: add tcp_delack_max() Eric Dumazet
2023-09-20 17:29 ` [PATCH net-next 1/3] net: constify sk_dst_get() and __sk_dst_get() argument Eric Dumazet
2023-09-20 17:29 ` [PATCH net-next 2/3] tcp: constify tcp_rto_min() and tcp_rto_min_us() argument Eric Dumazet
2023-09-20 17:29 ` [PATCH net-next 3/3] tcp: derive delack_max from rto_min Eric Dumazet
2023-09-20 17:34   ` Soheil Hassas Yeganeh
2023-09-20 19:06   ` Neal Cardwell
2023-09-20 21:57   ` David Ahern [this message]
2023-09-21  2:16     ` Eric Dumazet
2023-09-21 12:37       ` David Ahern
2023-09-21 12:58         ` Eric Dumazet
2023-09-22  9:59           ` David Laight
2023-09-22 10:53             ` Eric Dumazet
2023-09-22 16:51               ` David Laight
2023-10-01 12:20 ` [PATCH net-next 0/3] tcp: add tcp_delack_max() patchwork-bot+netdevbpf

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