Linux Ethernet Bridging - Sep 2013 - [Bridge] [PATCH 1/1] bridge: fix message_age_timer calculation

This changes the message_age_timer calculation to use the BPDU's max age as
opposed to the local bridge's max age.  This is in accordance with section
8.6.2.3.2 Step 2 of the 802.1D-1998 sprecification.

With the current implementation, when running with very large bridge diameters,
convergance will not always occur even if a root bridge is configured to have a
longer max age.

Tested successfully on bridge diameters of ~200.

Signed-off-by: Chris Healy <cphealy at gmail.com>
---
 net/bridge/br_stp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/bridge/br_stp.c b/net/bridge/br_stp.c
index 1c0a50f..f1887ba 100644
--- a/net/bridge/br_stp.c
+++ b/net/bridge/br_stp.c
@@ -209,7 +209,7 @@ static void br_record_config_information(struct
net_bridge_port *p,
 	p->designated_age = jiffies - bpdu->message_age;
 
 	mod_timer(&p->message_age_timer, jiffies
-		  + (p->br->max_age - bpdu->message_age));
+		  + (bpdu->max_age - bpdu->message_age));
 }
 
 /* called under bridge lock */
-- 
1.8.1.2

On Mon,  9 Sep 2013 09:56:08 -0700
Chris Healy <cphealy@gmail.com> wrote:
> This changes the message_age_timer calculation to use the BPDU''s
max age as opposed to the local bridge''s max age.  This is in
accordance with section 8.6.2.3.2 Step 2 of the 802.1D-1998 sprecification.
> 
> With the current implementation, when running with very large bridge
diameters, convergance will not always occur even if a root bridge is configured
to have a longer max age.
> 
> Tested successfully on bridge diameters of ~200.
> 
> Signed-off-by: Chris Healy <cphealy@gmail.com>
> ---
>  net/bridge/br_stp.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/bridge/br_stp.c b/net/bridge/br_stp.c
> index 1c0a50f..f1887ba 100644
> --- a/net/bridge/br_stp.c
> +++ b/net/bridge/br_stp.c
> @@ -209,7 +209,7 @@ static void br_record_config_information(struct
net_bridge_port *p,
>  	p->designated_age = jiffies - bpdu->message_age;
>  
>  	mod_timer(&p->message_age_timer, jiffies
> -		  + (p->br->max_age - bpdu->message_age));
> +		  + (bpdu->max_age - bpdu->message_age));
>  }
>  
>  /* called under bridge lock */
This makes sense.

Acked-by: Stephen Hemminger <stephen@networkplumber.org>

On Mon,  9 Sep 2013 09:56:08 -0700
Chris Healy <cphealy at gmail.com> wrote:
> This changes the message_age_timer calculation to use the BPDU's max
age as opposed to the local bridge's max age.  This is in accordance with
section 8.6.2.3.2 Step 2 of the 802.1D-1998 sprecification.
> 
> With the current implementation, when running with very large bridge
diameters, convergance will not always occur even if a root bridge is configured
to have a longer max age.
> 
> Tested successfully on bridge diameters of ~200.
> 
> Signed-off-by: Chris Healy <cphealy at gmail.com>
> ---
>  net/bridge/br_stp.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/bridge/br_stp.c b/net/bridge/br_stp.c
> index 1c0a50f..f1887ba 100644
> --- a/net/bridge/br_stp.c
> +++ b/net/bridge/br_stp.c
> @@ -209,7 +209,7 @@ static void br_record_config_information(struct
net_bridge_port *p,
>  	p->designated_age = jiffies - bpdu->message_age;
>  
>  	mod_timer(&p->message_age_timer, jiffies
> -		  + (p->br->max_age - bpdu->message_age));
> +		  + (bpdu->max_age - bpdu->message_age));
>  }
>  
>  /* called under bridge lock */
This makes sense.

Acked-by: Stephen Hemminger <stephen at networkplumber.org>

Hello.

On 09/09/2013 08:56 PM, Chris Healy wrote:
> This changes the message_age_timer calculation to use the BPDU's max
age as opposed to the local bridge's max age.  This is in accordance with
section 8.6.2.3.2 Step 2 of the 802.1D-1998 sprecification.
    You should wrap your changelog lines at 80 chars at most, preferably less.
> With the current implementation, when running with very large bridge
diameters, convergance will not always occur even if a root bridge is configured
to have a longer max age.
> Tested successfully on bridge diameters of ~200.
> Signed-off-by: Chris Healy <cphealy at gmail.com>
WBR, Sergei