[PATCH] tcp: remove useless update for flag parameter in tcp_enter_frto_loss()

[PATCH] tcp: remove useless update for flag parameter in tcp_enter_frto_loss()

[Li Yu]

It seem that we forget remove below two lines after copying code :)

This update never impacts others.

Sorry for last mail with legal notices improperly, I used wrong
mail.

Signed-off-by Li Yu <bingtian.ly@taobao.com>

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index e886e2f..b2f8ada 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -2169,8 +2169,6 @@ static void tcp_enter_frto_loss(struct sock *sk,
int allowed_segments, int flag)
 			/* For some reason this R-bit might get cleared? */
 			if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS)
 				tp->retrans_out += tcp_skb_pcount(skb);
-			/* ...enter this if branch just for the first segment */
-			flag |= FLAG_DATA_ACKED;
 		} else {
 			if (TCP_SKB_CB(skb)->sacked & TCPCB_RETRANS)
 				tp->undo_marker = 0;

Re: [PATCH] tcp: remove useless update for flag parameter in tcp_enter_frto_loss()

[Yuchung Cheng]

On Tue, Mar 27, 2012 at 9:23 PM, Li Yu <raise.sail@gmail.com> wrote:
>
> It seem that we forget remove below two lines after copying code :)
>
> This update never impacts others.
>
> Sorry for last mail with legal notices improperly, I used wrong
> mail.
>
> Signed-off-by Li Yu <bingtian.ly@taobao.com>
>
> diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
> index e886e2f..b2f8ada 100644
> --- a/net/ipv4/tcp_input.c
> +++ b/net/ipv4/tcp_input.c
> @@ -2169,8 +2169,6 @@ static void tcp_enter_frto_loss(struct sock *sk,
> int allowed_segments, int flag)
>                        /* For some reason this R-bit might get cleared? */
>                        if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS)
>                                tp->retrans_out += tcp_skb_pcount(skb);
> -                       /* ...enter this if branch just for the first segment */
> -                       flag |= FLAG_DATA_ACKED;

The comment explicitly explains why the flag is marked for.


>                } else {
>                        if (TCP_SKB_CB(skb)->sacked & TCPCB_RETRANS)
>                                tp->undo_marker = 0;
> --
> To unsubscribe from this list: send the line "unsubscribe netdev" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [PATCH] tcp: remove useless update for flag parameter in tcp_enter_frto_loss()

[Neal Cardwell]

On Wed, Mar 28, 2012 at 12:23 AM, Li Yu <raise.sail@gmail.com> wrote:
>
> It seem that we forget remove below two lines after copying code :)
>
> This update never impacts others.

The 'flag' variable will be used in later iterations of the
tcp_for_write_queue() loop. The comment seems to quite sensibly
indicate that the FLAG_DATA_ACKED bit is being set to avoid entering
that branch of the if statement in later segments in the loop:

2168                 if ((tp->frto_counter == 1) && !(flag & FLAG_DATA_ACKED)) {
2169                         /* For some reason this R-bit might get cleared? */
2170                         if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS)
2171                                 tp->retrans_out += tcp_skb_pcount(skb);
2172                         /* ...enter this if branch just for the
first segment */
2173                         flag |= FLAG_DATA_ACKED;
2174                 } else {

The structure of the logic seems intact from the original commit that
added this:

http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commitdiff;h=d1a54c6a0a3f9c2c4ef71982d89b8571bd9eaa51

neal

Re: [PATCH] tcp: remove useless update for flag parameter in tcp_enter_frto_loss()

[Li Yu]

于 2012年03月28日 13:29, Neal Cardwell 写道:
> On Wed, Mar 28, 2012 at 12:23 AM, Li Yu<raise.sail@gmail.com>  wrote:
>>
>> It seem that we forget remove below two lines after copying code :)
>>
>> This update never impacts others.
>
> The 'flag' variable will be used in later iterations of the
> tcp_for_write_queue() loop. The comment seems to quite sensibly
> indicate that the FLAG_DATA_ACKED bit is being set to avoid entering
> that branch of the if statement in later segments in the loop:
>
> 2168                 if ((tp->frto_counter == 1)&&  !(flag&  FLAG_DATA_ACKED)) {
> 2169                         /* For some reason this R-bit might get cleared? */
> 2170                         if (TCP_SKB_CB(skb)->sacked&  TCPCB_SACKED_RETRANS)
> 2171                                 tp->retrans_out += tcp_skb_pcount(skb);
> 2172                         /* ...enter this if branch just for the
> first segment */
> 2173                         flag |= FLAG_DATA_ACKED;
> 2174                 } else {
>
> The structure of the logic seems intact from the original commit that
> added this:
>
> http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commitdiff;h=d1a54c6a0a3f9c2c4ef71982d89b8571bd9eaa51
>

Sorry for spent time on this, it it account for F-RTO retransmitted
segment here.

Yu

> neal
>

Re: [PATCH] tcp: remove useless update for flag parameter in tcp_enter_frto_loss()

[Eric Dumazet]

On Wed, 2012-03-28 at 14:54 +0800, Li Yu wrote:

> Sorry for spent time on this, it it account for F-RTO retransmitted
> segment here.

I dont believe its waste of time having several eyes on this code.

Thanks

Re: [PATCH] tcp: remove useless update for flag parameter in tcp_enter_frto_loss()

[David Miller]

From: Li Yu <bingtian.ly@taobao.com>
Date: Wed, 28 Mar 2012 12:00:35 +0800

> This email (including any attachments) is confidential and may be legally privileged.

Do not post to the mailing list with legal notices such as this, not
only are they annoying, they are completely pointless when used on
a public mailing list.

I am completely ignoring your patches until you post them properly,
without these annoying notices attached.

[PATCH] tcp: remove useless update for flag parameter in tcp_enter_frto_loss()

[Li Yu]

It seem that we forget remove below two lines after copying code :)

This update never impacts others.

Signed-off-by Li Yu <bingtian.ly@taobao.com>

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index e886e2f..b2f8ada 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -2169,8 +2169,6 @@ static void tcp_enter_frto_loss(struct sock *sk,
int allowed_segments, int flag)
                        /* For some reason this R-bit might get cleared? */
                        if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS)
                                tp->retrans_out += tcp_skb_pcount(skb);
-                       /* ...enter this if branch just for the first segment */
-                       flag |= FLAG_DATA_ACKED;
                } else {
                        if (TCP_SKB_CB(skb)->sacked & TCPCB_RETRANS)
                                tp->undo_marker = 0;

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