Patchwork [net-next,v3,08/11] tbf: fix value set for q->ptokens

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Submitter Jiri Pirko
Date Feb. 9, 2013, 4:45 p.m.
Message ID <1360428312-1277-9-git-send-email-jiri@resnulli.us>
Download mbox | patch
Permalink /patch/219407/
State Changes Requested
Delegated to: David Miller
Headers show

Comments

Jiri Pirko - Feb. 9, 2013, 4:45 p.m.
q->ptokens is in ns and we are assigning q->mtu directly to it. That is
wrong. psched_l2t_ns() should be used to compute correct value.

Signed-off-by: Jiri Pirko <jiri@resnulli.us>
---
 net/sched/sch_tbf.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)
Eric Dumazet - Feb. 10, 2013, 1:30 a.m.
On Sat, 2013-02-09 at 17:45 +0100, Jiri Pirko wrote:
> q->ptokens is in ns and we are assigning q->mtu directly to it. That is
> wrong. psched_l2t_ns() should be used to compute correct value.
> 


Not clear why its a separate patch, and not folded in the 6th


> Signed-off-by: Jiri Pirko <jiri@resnulli.us>
> ---
>  net/sched/sch_tbf.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/net/sched/sch_tbf.c b/net/sched/sch_tbf.c
> index dc562a8..6e8b670 100644
> --- a/net/sched/sch_tbf.c
> +++ b/net/sched/sch_tbf.c
> @@ -165,8 +165,8 @@ static struct sk_buff *tbf_dequeue(struct Qdisc *sch)
>  
>  		if (q->peak_present) {
>  			ptoks = toks + q->ptokens;
> -			if (ptoks > (long)q->mtu)
> -				ptoks = q->mtu;
> +			if (ptoks > (s64) psched_l2t_ns(&q->peak, q->mtu))
> +				ptoks = (s64) psched_l2t_ns(&q->peak, q->mtu);

It seems a bit expensive to perform this in fast path.

Please add a variable to cache psched_l2t_ns(&q->peak, q->mtu)


>  			ptoks -= (s64) psched_l2t_ns(&q->peak, len);
>  		}
>  		toks += q->tokens;
> @@ -215,7 +215,8 @@ static void tbf_reset(struct Qdisc *sch)
>  	sch->q.qlen = 0;
>  	q->t_c = ktime_to_ns(ktime_get());
>  	q->tokens = q->buffer;
> -	q->ptokens = q->mtu;
> +	if (q->peak_present)
> +		q->ptokens = (s64) psched_l2t_ns(&q->peak, q->mtu);
>  	qdisc_watchdog_cancel(&q->watchdog);
>  }
>  
> @@ -296,11 +297,11 @@ static int tbf_change(struct Qdisc *sch, struct nlattr *opt)
>  	q->max_size = max_size;
>  	q->buffer = PSCHED_TICKS2NS(qopt->buffer);
>  	q->tokens = q->buffer;
> -	q->ptokens = q->mtu;
>  
>  	psched_ratecfg_precompute(&q->rate, rtab->rate.rate);
>  	if (ptab) {
>  		psched_ratecfg_precompute(&q->peak, ptab->rate.rate);
> +		q->ptokens = (s64) psched_l2t_ns(&q->peak, q->mtu);

Here probably.



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Jiri Pirko - Feb. 10, 2013, 8:18 a.m.
Sun, Feb 10, 2013 at 02:30:46AM CET, eric.dumazet@gmail.com wrote:
>On Sat, 2013-02-09 at 17:45 +0100, Jiri Pirko wrote:
>> q->ptokens is in ns and we are assigning q->mtu directly to it. That is
>> wrong. psched_l2t_ns() should be used to compute correct value.
>> 
>
>
>Not clear why its a separate patch, and not folded in the 6th

This is independent on 6th. Would be needed even if 6th wouldn't be
there.

>
>
>> Signed-off-by: Jiri Pirko <jiri@resnulli.us>
>> ---
>>  net/sched/sch_tbf.c | 9 +++++----
>>  1 file changed, 5 insertions(+), 4 deletions(-)
>> 
>> diff --git a/net/sched/sch_tbf.c b/net/sched/sch_tbf.c
>> index dc562a8..6e8b670 100644
>> --- a/net/sched/sch_tbf.c
>> +++ b/net/sched/sch_tbf.c
>> @@ -165,8 +165,8 @@ static struct sk_buff *tbf_dequeue(struct Qdisc *sch)
>>  
>>  		if (q->peak_present) {
>>  			ptoks = toks + q->ptokens;
>> -			if (ptoks > (long)q->mtu)
>> -				ptoks = q->mtu;
>> +			if (ptoks > (s64) psched_l2t_ns(&q->peak, q->mtu))
>> +				ptoks = (s64) psched_l2t_ns(&q->peak, q->mtu);
>
>It seems a bit expensive to perform this in fast path.
>
>Please add a variable to cache psched_l2t_ns(&q->peak, q->mtu)

Okay, I did not think that this is necessary, but sure, I will do that.

Thanks!

>
>
>>  			ptoks -= (s64) psched_l2t_ns(&q->peak, len);
>>  		}
>>  		toks += q->tokens;
>> @@ -215,7 +215,8 @@ static void tbf_reset(struct Qdisc *sch)
>>  	sch->q.qlen = 0;
>>  	q->t_c = ktime_to_ns(ktime_get());
>>  	q->tokens = q->buffer;
>> -	q->ptokens = q->mtu;
>> +	if (q->peak_present)
>> +		q->ptokens = (s64) psched_l2t_ns(&q->peak, q->mtu);
>>  	qdisc_watchdog_cancel(&q->watchdog);
>>  }
>>  
>> @@ -296,11 +297,11 @@ static int tbf_change(struct Qdisc *sch, struct nlattr *opt)
>>  	q->max_size = max_size;
>>  	q->buffer = PSCHED_TICKS2NS(qopt->buffer);
>>  	q->tokens = q->buffer;
>> -	q->ptokens = q->mtu;
>>  
>>  	psched_ratecfg_precompute(&q->rate, rtab->rate.rate);
>>  	if (ptab) {
>>  		psched_ratecfg_precompute(&q->peak, ptab->rate.rate);
>> +		q->ptokens = (s64) psched_l2t_ns(&q->peak, q->mtu);
>
>Here probably.
>
>
>
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Eric Dumazet - Feb. 10, 2013, 8:21 a.m.
On Sun, 2013-02-10 at 09:18 +0100, Jiri Pirko wrote:
> Sun, Feb 10, 2013 at 02:30:46AM CET, eric.dumazet@gmail.com wrote:
> >On Sat, 2013-02-09 at 17:45 +0100, Jiri Pirko wrote:
> >> q->ptokens is in ns and we are assigning q->mtu directly to it. That is
> >> wrong. psched_l2t_ns() should be used to compute correct value.
> >> 
> >
> >
> >Not clear why its a separate patch, and not folded in the 6th
> 
> This is independent on 6th. Would be needed even if 6th wouldn't be
> there.

When was this bug introduced then ?


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Jiri Pirko - Feb. 10, 2013, 8:51 a.m.
Sun, Feb 10, 2013 at 09:21:38AM CET, eric.dumazet@gmail.com wrote:
>On Sun, 2013-02-10 at 09:18 +0100, Jiri Pirko wrote:
>> Sun, Feb 10, 2013 at 02:30:46AM CET, eric.dumazet@gmail.com wrote:
>> >On Sat, 2013-02-09 at 17:45 +0100, Jiri Pirko wrote:
>> >> q->ptokens is in ns and we are assigning q->mtu directly to it. That is
>> >> wrong. psched_l2t_ns() should be used to compute correct value.
>> >> 
>> >
>> >
>> >Not clear why its a separate patch, and not folded in the 6th
>> 
>> This is independent on 6th. Would be needed even if 6th wouldn't be
>> there.
>
>When was this bug introduced then ?

This has been present since the beginning of git. I'm unable to find bk
repo right now to tell you bk commit :/
>
>
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Eric Dumazet - Feb. 10, 2013, 6 p.m.
On Sun, 2013-02-10 at 09:51 +0100, Jiri Pirko wrote:
> Sun, Feb 10, 2013 at 09:21:38AM CET, eric.dumazet@gmail.com wrote:
> >On Sun, 2013-02-10 at 09:18 +0100, Jiri Pirko wrote:
> >> Sun, Feb 10, 2013 at 02:30:46AM CET, eric.dumazet@gmail.com wrote:
> >> >On Sat, 2013-02-09 at 17:45 +0100, Jiri Pirko wrote:
> >> >> q->ptokens is in ns and we are assigning q->mtu directly to it. That is
> >> >> wrong. psched_l2t_ns() should be used to compute correct value.
> >> >> 
> >> >
> >> >
> >> >Not clear why its a separate patch, and not folded in the 6th
> >> 
> >> This is independent on 6th. Would be needed even if 6th wouldn't be
> >> there.
> >
> >When was this bug introduced then ?
> 
> This has been present since the beginning of git. I'm unable to find bk
> repo right now to tell you bk commit :/

Current code doesnt store ptokens in ns, your patch is very confusing.

q->mtu is properly setup by tc command.

Its not dev->mtu at all.

I claim you fix a bug added in 6th patch.

It makes no sense to me to introduce a bug in 6th and fix it in 8th.



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Jiri Pirko - Feb. 10, 2013, 6:37 p.m.
Sun, Feb 10, 2013 at 07:00:08PM CET, eric.dumazet@gmail.com wrote:
>On Sun, 2013-02-10 at 09:51 +0100, Jiri Pirko wrote:
>> Sun, Feb 10, 2013 at 09:21:38AM CET, eric.dumazet@gmail.com wrote:
>> >On Sun, 2013-02-10 at 09:18 +0100, Jiri Pirko wrote:
>> >> Sun, Feb 10, 2013 at 02:30:46AM CET, eric.dumazet@gmail.com wrote:
>> >> >On Sat, 2013-02-09 at 17:45 +0100, Jiri Pirko wrote:
>> >> >> q->ptokens is in ns and we are assigning q->mtu directly to it. That is
>> >> >> wrong. psched_l2t_ns() should be used to compute correct value.
>> >> >> 
>> >> >
>> >> >
>> >> >Not clear why its a separate patch, and not folded in the 6th
>> >> 
>> >> This is independent on 6th. Would be needed even if 6th wouldn't be
>> >> there.
>> >
>> >When was this bug introduced then ?
>> 
>> This has been present since the beginning of git. I'm unable to find bk
>> repo right now to tell you bk commit :/
>
>Current code doesnt store ptokens in ns, your patch is very confusing.
>
>q->mtu is properly setup by tc command.

Now I get it. q->mtu is not bytes but time instead. I will fix my patches.

>
>Its not dev->mtu at all.
>
>I claim you fix a bug added in 6th patch.
>
>It makes no sense to me to introduce a bug in 6th and fix it in 8th.
>
>
>
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Patch

diff --git a/net/sched/sch_tbf.c b/net/sched/sch_tbf.c
index dc562a8..6e8b670 100644
--- a/net/sched/sch_tbf.c
+++ b/net/sched/sch_tbf.c
@@ -165,8 +165,8 @@  static struct sk_buff *tbf_dequeue(struct Qdisc *sch)
 
 		if (q->peak_present) {
 			ptoks = toks + q->ptokens;
-			if (ptoks > (long)q->mtu)
-				ptoks = q->mtu;
+			if (ptoks > (s64) psched_l2t_ns(&q->peak, q->mtu))
+				ptoks = (s64) psched_l2t_ns(&q->peak, q->mtu);
 			ptoks -= (s64) psched_l2t_ns(&q->peak, len);
 		}
 		toks += q->tokens;
@@ -215,7 +215,8 @@  static void tbf_reset(struct Qdisc *sch)
 	sch->q.qlen = 0;
 	q->t_c = ktime_to_ns(ktime_get());
 	q->tokens = q->buffer;
-	q->ptokens = q->mtu;
+	if (q->peak_present)
+		q->ptokens = (s64) psched_l2t_ns(&q->peak, q->mtu);
 	qdisc_watchdog_cancel(&q->watchdog);
 }
 
@@ -296,11 +297,11 @@  static int tbf_change(struct Qdisc *sch, struct nlattr *opt)
 	q->max_size = max_size;
 	q->buffer = PSCHED_TICKS2NS(qopt->buffer);
 	q->tokens = q->buffer;
-	q->ptokens = q->mtu;
 
 	psched_ratecfg_precompute(&q->rate, rtab->rate.rate);
 	if (ptab) {
 		psched_ratecfg_precompute(&q->peak, ptab->rate.rate);
+		q->ptokens = (s64) psched_l2t_ns(&q->peak, q->mtu);
 		q->peak_present = true;
 	} else {
 		q->peak_present = false;